Article: 223798 of rec.radio.amateur.antenna From: Roy Lewallen Subject: Re: MFJ Tuner "Current Balun" conversion. Date: Tue, 25 Apr 2006 00:44:03 -0700 Message-ID: <124rkq5ivspsh0f@corp.supernews.com> References: <1145908745.710199.188670@e56g2000cwe.googlegroups.com> <124qf1p28ssj7e0@corp.supernews.com> <124qjqncqgspg51@corp.supernews.com> <1145929001.979317.115910@i39g2000cwa.googlegroups.com> <1145933277.951517.23900@u72g2000cwu.googlegroups.com> <124r9oiqspf3527@corp.supernews.com> Ian White GM3SEK wrote: > Roy Lewallen wrote: >> n3ox.dan@gmail.com wrote: >>> . . . >>> Will a 4:1 current balun transform a random impedance Z1 to Z2 where >>> |Z2|=|Z1|/4? I know Roy pointed out that this won't work for a voltage >>> balun... >> >> No, it won't either. The amount of error with any balun type depends >> on the balun construction. You'll just have to build one and see what >> it does. >> >> It would be interesting to know what your antenna Z looks like on each >> band at the input to the existing balun. That is, what do you get when >> you connect your antenna to the balun output and the analyzer to the >> balun input? > > Since the balun is connected to a tuner, inaccurate impedance > transformation won't matter much. The only concern would be if it's a > sign of some other problem in the balun. > Well, yes and no. Good tuner designers go to a lot of trouble to maximize the Q of the inductors to minimize loss. It's doubtful that the Q of the balun inductance is nearly as good, so loss is liable to be higher if the balun is contributing a significant amount of reactance. Otherwise, I agree, it doesn't make much difference. The balun might move the impedance to a point where the tuner can't match it, but it's just as likely that it'll move an otherwise unmatchable impedance to within the tuner's range. Roy Lewallen, W7EL Article: 223799 of rec.radio.amateur.antenna From: Roy Lewallen Subject: Re: MFJ Tuner "Current Balun" conversion. Date: Tue, 25 Apr 2006 01:50:29 -0700 Message-ID: <124romns9644t7c@corp.supernews.com> References: <1145908745.710199.188670@e56g2000cwe.googlegroups.com> <124qf1p28ssj7e0@corp.supernews.com> <124qjqncqgspg51@corp.supernews.com> <1145929001.979317.115910@i39g2000cwa.googlegroups.com> <1145933277.951517.23900@u72g2000cwu.googlegroups.com> <124r9oiqspf3527@corp.supernews.com> Reg Edwards wrote: > A choke balun has NO impedance or turns ratio. It is silly to refer to > one. Consider me silly as well as an "old wife". A choke balun has common mode impedance, and that impedance is its single most important quality. If the common mode impedance isn't adequate, it won't perform its function. It can be measured by short circuiting the input conductors together and output conductors together to temporarily make one conductor, and measuring the impedance between the ends. > . . . > All the talk about saturation is so much hot air. You couldn't > saturate it even if you tried. The currents in the two wires run in > opposite directions and cancel each other out. I agree that saturation isn't a problem, but disagree about the reason. Core flux density is a function of the common mode current, which is in the same direction in the wires and doesn't cancel out. The objective of the balun is to minimize this current, but in a high power system even with an effective balun, the I^2 * R loss, where I is the common mode current, can still get large enough to make the core hot. However, if you use a high-permeability, low frequency ferrite, the flux density will still be way below saturation even when the core is hot enough to break. > . . . Roy Lewallen, W7EL Article: 223800 of rec.radio.amateur.antenna Date: Tue, 25 Apr 2006 07:20:19 -0500 From: Tom Ring Subject: Re: Velocity Factor and resonant frequency References: <124qfaq4636hq11@corp.supernews.com> <6O2dnfHF5slNzdDZnZ2dnUVZ8tKdnZ2d@bt.com> <124qlp7fe41g87a@corp.supernews.com> <1145927357.742041.218170@v46g2000cwv.googlegroups.com> Message-ID: <444e1403$0$1012$39cecf19@news.twtelecom.net> Tom Donaly wrote: > > What is the transmission mode in a single conductor transmission line? That is a good question. I'd never thought about it. Anyone here have experience with G Line? tom K0TAR Article: 223801 of rec.radio.amateur.antenna From: "Tom Donaly" Subject: Re: Velocity Factor and resonant frequency References: <124qfaq4636hq11@corp.supernews.com> <6O2dnfHF5slNzdDZnZ2dnUVZ8tKdnZ2d@bt.com> <124qlp7fe41g87a@corp.supernews.com> <1145927357.742041.218170@v46g2000cwv.googlegroups.com> <444e1403$0$1012$39cecf19@news.twtelecom.net> Message-ID: <9aq3g.14186$4L1.2677@newssvr11.news.prodigy.com> Date: Tue, 25 Apr 2006 14:15:33 GMT Dave wrote: > Tom Ring wrote: > >> Tom Donaly wrote: >> >>> >>> What is the transmission mode in a single conductor transmission line? >> >> >> >> That is a good question. I'd never thought about it. Anyone here >> have experience with G Line? >> >> tom >> K0TAR > > > The questions needs further refinement. Over a plane or in free space? > No ground planes allowed. 73, Tom Donaly, KA6RUH Article: 223802 of rec.radio.amateur.antenna Date: Tue, 25 Apr 2006 09:23:21 -0500 From: Tom Ring Subject: Re: Velocity Factor and resonant frequency References: <124qfaq4636hq11@corp.supernews.com> <6O2dnfHF5slNzdDZnZ2dnUVZ8tKdnZ2d@bt.com> <124qlp7fe41g87a@corp.supernews.com> <1145927357.742041.218170@v46g2000cwv.googlegroups.com> <444e1403$0$1012$39cecf19@news.twtelecom.net> Message-ID: <444e30da$0$1012$39cecf19@news.twtelecom.net> Dave wrote: > Tom Ring wrote: > >> Tom Donaly wrote: >> >>> >>> What is the transmission mode in a single conductor transmission line? >> >> >> >> That is a good question. I'd never thought about it. Anyone here >> have experience with G Line? >> >> tom >> K0TAR > > > The questions needs further refinement. Over a plane or in free space? > Properly made and installed, G Line shouldn't know the difference. tom K0TAR Article: 223803 of rec.radio.amateur.antenna Date: Tue, 25 Apr 2006 10:00:45 -0500 From: Tom Ring Subject: Re: Velocity Factor and resonant frequency References: <124qfaq4636hq11@corp.supernews.com> <6O2dnfHF5slNzdDZnZ2dnUVZ8tKdnZ2d@bt.com> <124qlp7fe41g87a@corp.supernews.com> <1145927357.742041.218170@v46g2000cwv.googlegroups.com> <444e1403$0$1012$39cecf19@news.twtelecom.net> <444e30da$0$1012$39cecf19@news.twtelecom.net> Message-ID: <444e399e$0$1007$39cecf19@news.twtelecom.net> Dave wrote: > Tom Ring wrote: > > Tom, the original question is a single conductor transmission line. A > single conductor transmission line is used to feed a 'classic Windom'. > > In that configuration, is it a G line? > > For the uninitiated, including this questioner, what is a G line? > I don't believe a single bare wire will operate as a transmission line in free space. It will radiate. G line, on the other hand, will not. At least it won't radiate any more than a piece of coax. And it can be used in reasonably normal situations, but no sharp bends. It is not practical for HF, however. 70 cm would probably be as low as you would want to go. The quick description is that G line is a wire coated with a dielectric to a specific thickness that is coupled to by a device resembling a feedhorn on each end, where the horn is a flaring of the shield. As I remember it, the dielectric discontinuity constrains the E field, and hence the EM field. The losses are much lower than coax, on the order of 5 dB per mile at 500 MHz. For details see - http://coldwar-c4i.net/G-Line/EE0860/p638.html tom K0TAR Article: 223804 of rec.radio.amateur.antenna From: "jimmiefender@bellsouth.net" References: <1145912884.770796.133430@v46g2000cwv.googlegroups.com> Subject: Re: mobile loading coils Message-ID: Date: Tue, 25 Apr 2006 11:22:15 -0400 wrote in message news:1145912884.770796.133430@v46g2000cwv.googlegroups.com... > >Thanks Cecil, I have some old fiberglass 11m antennas, the kind that has > >a >>wire antenna heatshrinked to a fiberglass rod that would be pefect for >>making this. .................................... > > You can use one of those for all those bands, just by changing the > top "stinger" whip. I use the small hose clamps to hold them, if the > stick doesn't have a slide in mounting part on top. > IE: if you had a 6 ft CB stick that used a short stinger, you can add > length to tune the lower bands. On one of mine, the stinger needed to > be about 2 ft longer to tune 20m using the CB stick. So if you had > various > stingers to clip on, you could work all the bands from 20-10. > On those upper HF bands, even the simple CB stick/extended stinger > will work quite well. A cb/10m stick using a longer stinger to tune > 20m, > is more efficient than most 20m sticks using more turns of wire, and a > shorter stinger. > I have one antenna that I've used for nearly 15 years that was built > from a > firestick CB antenna. I added a large coil in the middle, and it works > all > bands 80-10. I change coil taps on the low bands, stinger length on the > > upper bands. > I also have one I made from a 6 ft 20m stick. It's also converted to > all > band use, and has the performance of a bugcatcher, being it uses a > large > coil on the lower bands. But...it's as light as a fishing rod n reel... > I use a 5 ft stinger, and the normal driving height of the antenna is > 11 ft. > That antenna is exactly center loaded in the driving mode. If I add a > 3 ft > mast, it's 14 ft tall, with the coil at the 8 ft level. But I use that > when parked. > Bit tall for driving... :/ Anyway, you can build a pretty good antenna > dirt > cheap if you look around. I've never spent more than junk parts and > chump change for a mobile antenna. > MK > I had taken an old CB 6ft antenna, the kind with the wire heatshrinked to the side and put new wire and a loading coil in the middle. Works OK on 10 and 15 SWR is pretty high on 20 and I dont have a way to match it. Experimented with a cane pole for a support and found I could get a reasoable SWR on 20 if the antenna was about 14ft long, a couple more feet and I wouldnt even need the coil. Next plan is to try to use something that folds kind of like fiberglass tent poles and get away from the loading coils all together. They are more of a bother than what they are worth for my application since I dont ham while Im driving. I just wanted something I could store neatly in the back of the truck which would limit eveything to 6Ft or less. Changed my mind about 5 times now on what I want and how to do it, I guess that happens when you are going up the learning curve. Article: 223805 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Velocity Factor and resonant frequency References: <124qfaq4636hq11@corp.supernews.com> <6O2dnfHF5slNzdDZnZ2dnUVZ8tKdnZ2d@bt.com> <124qlp7fe41g87a@corp.supernews.com> <1145927357.742041.218170@v46g2000cwv.googlegroups.com> <444e1403$0$1012$39cecf19@news.twtelecom.net> <444e30da$0$1012$39cecf19@news.twtelecom.net> <444e399e$0$1007$39cecf19@news.twtelecom.net> Message-ID: Date: Tue, 25 Apr 2006 15:35:59 GMT Tom Ring wrote: > I don't believe a single bare wire will operate as a transmission line > in free space. Let's say we have a 1/2WL dipole in free space driven by a self-contained source at the center. If we float a florescent light bulb around the ends of the dipole, are you saying the electric fields won't fire the bulb like it does on earth? -- 73, Cecil http://www.qsl.net/w5dxp Article: 223806 of rec.radio.amateur.antenna From: Fred Subject: Re: blame those that enage in gaybashing for the gay bashing posts Message-ID: References: <1145928382.424886.232730@i40g2000cwc.googlegroups.com> Date: Tue, 25 Apr 2006 17:27:32 GMT On 24 Apr 2006 18:26:22 -0700, "an_old_friend" wrote: > >Slow Code wrote: >> Fred wrote in >> news:rgvl42tilp789fgb9oqttm530qeu843upv@4ax.com: >> >west >> > >> > Can you read? Markie is here pushing his gay agenda and he is spamming >> > our group. Why do you choose to be so dense? >> >> >> Just to stir I'm thinking. He must get a kick out of watching Mark >> butcher the english language day in & day out. > >or just can't face the facts I have the same rights he does If you have the right to push your gay agenda then we are all allowed to publicly laugh at your confused ass. You can't even pick sides sexually, yet you push the gay lifestyle hard. Find your rainbow, Mark. Then catch a case of AIDS and make the world a better place. Article: 223807 of rec.radio.amateur.antenna Date: Tue, 25 Apr 2006 13:16:48 -0500 From: Tom Ring Subject: Re: Velocity Factor and resonant frequency References: <124qfaq4636hq11@corp.supernews.com> <6O2dnfHF5slNzdDZnZ2dnUVZ8tKdnZ2d@bt.com> <124qlp7fe41g87a@corp.supernews.com> <1145927357.742041.218170@v46g2000cwv.googlegroups.com> <444e1403$0$1012$39cecf19@news.twtelecom.net> <444e30da$0$1012$39cecf19@news.twtelecom.net> <444e399e$0$1007$39cecf19@news.twtelecom.net> Message-ID: <444e6790$0$1007$39cecf19@news.twtelecom.net> Cecil Moore wrote: > Tom Ring wrote: > >> I don't believe a single bare wire will operate as a transmission line >> in free space. > > > Let's say we have a 1/2WL dipole in free space driven by a > self-contained source at the center. If we float a florescent > light bulb around the ends of the dipole, are you saying the > electric fields won't fire the bulb like it does on earth? Stop acting like an idiot Cecil. tom K0TAR Article: 223808 of rec.radio.amateur.antenna From: Roy Lewallen Subject: Re: Velocity Factor and resonant frequency Date: Tue, 25 Apr 2006 11:31:14 -0700 Message-ID: <124sqnlh28cqg87@corp.supernews.com> References: <124qfaq4636hq11@corp.supernews.com> <6O2dnfHF5slNzdDZnZ2dnUVZ8tKdnZ2d@bt.com> <124qlp7fe41g87a@corp.supernews.com> <1145927357.742041.218170@v46g2000cwv.googlegroups.com> <444e1403$0$1012$39cecf19@news.twtelecom.net> It's a mistake to think that just because an antenna looks like it has one wire (although it really always has two) that it bears any similarity to a G line in operation. Whatever mode a G line effects, it isn't the same as an antenna -- a G line doesn't radiate significantly unless bent or improperly constructed. Roy Lewallen, W7EL Tom Ring wrote: > Tom Donaly wrote: > >> >> What is the transmission mode in a single conductor transmission line? > > That is a good question. I'd never thought about it. Anyone here have > experience with G Line? > > tom > K0TAR Article: 223809 of rec.radio.amateur.antenna Date: Tue, 25 Apr 2006 13:47:58 -0500 From: Tom Ring Subject: Re: Velocity Factor and resonant frequency References: <124qfaq4636hq11@corp.supernews.com> <6O2dnfHF5slNzdDZnZ2dnUVZ8tKdnZ2d@bt.com> <124qlp7fe41g87a@corp.supernews.com> <1145927357.742041.218170@v46g2000cwv.googlegroups.com> <444e1403$0$1012$39cecf19@news.twtelecom.net> <444e30da$0$1012$39cecf19@news.twtelecom.net> <444e399e$0$1007$39cecf19@news.twtelecom.net> <1145979892.771057.165540@y43g2000cwc.googlegroups.com> Message-ID: <444e6edf$0$1015$39cecf19@news.twtelecom.net> Ian White GM3SEK wrote: > To sum up, the G-line surface wave is very different from the normal TEM > waves around an isolated wire. Unless you take specific steps to excite > this particular mode, it won't occur at all, so it isn't relevant to the > main topic under discussion. > Ian, Thanks for the explanation. It was very helpful as well as concise. And I didn't think it had much to do with the main topic when I diverted to this one, except for the phrase "single wire transmission line", but that never stopped anyone else here before! ;) tom K0TAR Article: 223810 of rec.radio.amateur.antenna From: dplatt@radagast.org (Dave Platt) Subject: Re: how to prevent signal collision @ 2.4ghz Date: Tue, 25 Apr 2006 19:28:08 -0000 Message-ID: <124su28i4pg2dbb@corp.supernews.com> References: <1145967511.918039.80240@u72g2000cwu.googlegroups.com> In article <1145967511.918039.80240@u72g2000cwu.googlegroups.com>, mazerom wrote: >1. what will happen when you have two transmitters(digital spectrum) @ >the same carrier freqeuncy and is received by a superhet receiver >exactly at the same time, although unlikely (2.4ghz ISM band) The same thing that happens in any similar situation at lower frequencies. The two carriers will interfere. Unless they are accurately locked to a common frequency reference (unlikely) there will be a significant beating between them. The information-carrying sidebands of the two transmissions are likely to interfere, and the transmissions are likely to be garbled at their intended reception points. The degree of garbling/interference will depend on the signal strengths and also on the modulation scheme used. >2. what are ways and means to prevent this collision?csma/ca?rts/cts >setup?how? There are several approaches which have been used. The simplest is probably CSMA/CA, where each stations listens, doesn't transmit when it detects a carrier, and waits for some variable amount of time (often randomly-chosen) after carrier goes away before it starts transmitting. You'll tend to find this used in ad-hoc networks of various sorts, where there's no central coordinating authority for the right-to-transmit. For example, most amateur-radio AX.25 packet networks here in the US work this way. Collision rate tends to go up, and bandwidth utilization maxes out and decreases when there are many stations trying to operate on a single frequency. The classic problem with CSMA/CA on radio is the "hidden node" problem. If two nodes can't hear one another, they can't avoid one another... and their transmissions can often both be heard at other stations and will interfere. A second approach is an RTS/CTS system, coordinated by a central node which can be heard by all other nodes. This is a common mode on 802.11b networks, where coordination is performed by the 802.11b access point. A third approach is a polling approach, where the outlying nodes never transmit (not even an RTS) until specifically polled by the central authority-node. I believe that many of the AX.25 packet networks in Europe use this approach, in order to minimize collisions and improve bandwidth utilization over what's possible with CSMA/CA. If there's no central authority to handle polling or RTS/CTS, then some form of ad-hoc "token passing" can be used, where each node receives an explicit handoff of the right-to-transmit from another node, and either sends what it has to send, or forwards the right-to- transmit packet to the next node in the sequence. Time-division multiplexing (e.g. slotted Aloha) is another method... nodes coordinate to agree on which time slots each is allowed to transmit in. This can minimize or eliminate collisions (except perhaps during setup) but it can waste bandwidth, because timeslots can go unused if the nodes which "own" them don't have anything to say at the moment. So - there are lots of approaches - which one is best depends a great deal on the environment and application. -- Dave Platt AE6EO Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior I do _not_ wish to receive unsolicited commercial email, and I will boycott any company which has the gall to send me such ads! Article: 223811 of rec.radio.amateur.antenna From: richardharrison@webtv.net (Richard Harrison) Subject: Re: Velocity Factor and resonant frequency Date: Tue, 25 Apr 2006 14:42:14 -0500 Message-ID: <8483-444E7B96-1025@storefull-3254.bay.webtv.net> References: Reg, G4FGQ wrote: "I`m even more certain you will find an equation for inductance of an isolated wire of length L: and diameter D somewhere in the bibles." Equation 14 on page 48 of Terman`s 1943 edition of "Radio Engineers` Handbook is: Lo = 0.00508 l (2.303 log 4l/d - 1+mu/4) microhenrys Lo is the (approximate) low-frequency inductance and the dimensions are in inches. Terman also gives the (approximate) low-frequency inductance formula of a single-layer solenoid on page 55 of the same book. One can find the resonant frequency of the coil when using a known capacitance to resonate the coil at a low frequency. Maybe a dip meter could be used. Capacitive and inductive reactances are equal at resonance. Self and stray capacitances are included with the known value of capacitance used to resonate the coil at the low frequency. The resonant frequency is lower than the known capacitance by itself would produce. The resonance formula used with the actual inductance of the coil will give the capacitance of the resonant circuit The difference between the calculated capacitance and the known capacitor value is equal to the stray and self-capacitance total, so it is good to minimise stray capacitance when seeking the self-capacitance value of the coil. An ARRL Single-Layer Coil Winding Calculator is a slide rule which makes things easy. Best regards, Richard Harrison, KB5WZI Article: 223812 of rec.radio.amateur.antenna From: "Steve N." Subject: Re: I blame the ARRL for all the homosexual posts. Please Read. Date: Tue, 25 Apr 2006 14:38:25 -0500 Message-ID: References: Chill guys. Think a moment...Who's the lame of mind here. The OP with 1 post or the 60 responses... Looks like he suckered y'all in and had the desired effect 73, Steve, K9DCI "Skirt Chaser" **** NOTE: his brain dont [sic] either... Article: 223813 of rec.radio.amateur.antenna From: Roy Lewallen Subject: Re: Velocity Factor and resonant frequency Date: Tue, 25 Apr 2006 14:59:10 -0700 Message-ID: <124t6thopj1pea7@corp.supernews.com> References: <8483-444E7B96-1025@storefull-3254.bay.webtv.net> That's all very nice. Let's see if it's useful for anything. A while back, Cecil posted a model of a base loaded vertical antenna. It has an inductor which is vertically oriented. The bottom of the inductor is 1 foot from the ground and the inductor is 1 foot long and six inches in diameter. Inductance is 38.5 uH and it's self resonant at 13.48 MHz. (Moving it very far from ground changes the resonant frequency to 13.52 MHz.) What's it's velocity factor, and how did you calculate it? Roy Lewallen, W7EL Richard Harrison wrote: > Reg, G4FGQ wrote: > "I`m even more certain you will find an equation for inductance of an > isolated wire of length L: and diameter D somewhere in the bibles." > > Equation 14 on page 48 of Terman`s 1943 edition of "Radio Engineers` > Handbook is: > > Lo = 0.00508 l (2.303 log 4l/d - 1+mu/4) microhenrys > > Lo is the (approximate) low-frequency inductance and the dimensions are > in inches. > > Terman also gives the (approximate) low-frequency inductance formula of > a single-layer solenoid on page 55 of the same book. > > One can find the resonant frequency of the coil when using a known > capacitance to resonate the coil at a low frequency. Maybe a dip meter > could be used. Capacitive and inductive reactances are equal at > resonance. Self and stray capacitances are included with the known value > of capacitance used to resonate the coil at the low frequency. The > resonant frequency is lower than the known capacitance by itself would > produce. > > The resonance formula used with the actual inductance of the coil will > give the capacitance of the resonant circuit > > The difference between the calculated capacitance and the known > capacitor value is equal to the stray and self-capacitance total, so it > is good to minimise stray capacitance when seeking the self-capacitance > value of the coil. > > An ARRL Single-Layer Coil Winding Calculator is a slide rule which makes > things easy. > > Best regards, Richard Harrison, KB5WZI > Article: 223814 of rec.radio.amateur.antenna From: chuck Subject: Re: Velocity Factor and resonant frequency References: <124qfaq4636hq11@corp.supernews.com> <6O2dnfHF5slNzdDZnZ2dnUVZ8tKdnZ2d@bt.com> <124qlp7fe41g87a@corp.supernews.com> Message-ID: Date: Tue, 25 Apr 2006 23:17:04 GMT Roy Lewallen wrote: > I did a search quite some time ago and failed completely in finding the > formula you describe, in Terman or any other "bible". The formula for > the capacitance of an isolated sphere is common, but not a cylinder. The > formula for a coaxial capacitor is common also, but the capacitance > calculated from it approaches zero as the outer cylinder diameter gets > infinite. > Roy, I can't answer the question you put to Reg, but the capacitance of an isolated conducting cylinder is approximately that of an isolated conducting sphere of the same surface area. Any unbalanced charge on a conductor resides on the surface of the conductor and so the greater the surface area, the greater the charge you can place on it to raise its potential by some amount, etc. Obviously the cylinder's electric field would depart from the radial field of a point charge at the center of the sphere but I don't think that's relevant in this case. I hear bells ringing. ;-) Chuck > Maybe you could take a look after the wine wears off, and see if you can > locate the formula. By your earlier posting, it sounds like you've used > it frequently, so it shouldn't be too hard to find. I'd appreciate it > greatly if you would. And yes, I would make use of the formula -- I'm > very curious about how well a coil can be simulated as a transmission > line. The formula you use would be valid only in isolation, so > capacitance to other wires, current carrying conductors, and so forth > would have an appreciable effect. I showed not long ago that capacitance > from a base loading coil to ground has a very noticeable effect. Do you > have a way of taking that into account also? > > Roy Lewallen, W7EL > > Reg Edwards wrote: > >>> How do you calculate the coil C to use in the transmission line >> >> formulas? >> >>> Roy Lewallen, W7EL >> >> =================================== >> >> I'm surprised a person of your knowledge asked. >> >> Go to Terman's or other bibles, I'm sure you'll find it somewhere, and >> find the formula to calculate the DC capacitance to its surroundings >> of a cylinder of length L and diameter D. >> >> Then do the obvious and distribute the capacitance uniformly along its >> length. >> >> The formula will very likely be found in the same chapter as the >> inductance of a wire of given length and diameter. >> >> I have the capacitance formula I derived myself somewhere in my >> ancient tattered notes but I can't remember which of the A to S >> volumes it is in. >> >> I'm 3/4 ot the way down a bottle of French Red plonk. But Terman et >> al should be be quite good enough for your purposes. >> >> And its just the principle of the thing which matters. It's simple >> enough. I don't suppose you will make use of a formula if and when >> you find one. >> ---- >> Reg. >> >> Article: 223815 of rec.radio.amateur.antenna From: Allisonnospam@nouce.bellatlantic.net Subject: Re: J_Pole Trials and Tribulations Message-ID: <35dt42tngslkqbnqnl7uohk6jjhe21bgpv@4ax.com> References: Date: Tue, 25 Apr 2006 23:47:44 GMT On Tue, 25 Apr 2006 15:41:30 -0600, jimbo wrote: >I have been trying to get an acceptable 2 meter antenna installed in >my attic. A J-Pole seemed to me the best solution for my attic space. >You may recall an earlier post where I discussed SWR on one of the >ladder line J-Poles I was working with. Well, I gave up on ladder line >and constructed a J-Pole from 1/2 inch copper tubing. I tuned it in my >basement work shop to give the best SWR and then took it up to the >attic. The following table shows the results. > > Basement Attic > >144 1.90 1.80 >145 1.65 2.00 >146 1.50 2.10 >147 1.60 2.25 >147.995 1.90 2.25 > >Actually, probably not that bad for a first attempt at copper tubing. >But, I didn't like the fact that SWR was above 2.0 in my attic and >that things changed between my basement shop and the attic. I guess >this design is influenced by objects close by. Yep, take a half inch off the long pole and try again. It should improve but may not hit the mark. If you trim more then only 1/8th inch chops. Reset the feed point (tap) afterwards. A SWR of 1:1 is possible but only in place as moving it will alter tuning. > >So, somewhere in my surfing I came across the Arrow J-Pole. This is an >end fed, open stub commercial design that promises less that 1.5 SWR >across the band. Here are the results of my experiment with this antenna. > > Basement Attic > >144 1.10 1.22 >145 1.18 1.10 >146 1.25 1.20 >147 1.30 1.32 >147.995 1.40 1.42 > >Not 1.0 SWR but certainly met the promise. And the best thing about >this design is that near by objects don't seem to have an impact on >performance. If I built one of these designs and tuned it in my >basement shop, it should give the same results in the attic. > >Anyway, just my subjective observations. > >jimbo - AJ7IM What you have discovered is that antennas (resonant antennas) interact with the environment and will be detuned. Allison Article: 223816 of rec.radio.amateur.antenna From: Roy Lewallen Subject: Re: Velocity Factor and resonant frequency Date: Tue, 25 Apr 2006 17:11:23 -0700 Message-ID: <124telebjpfet2b@corp.supernews.com> References: <8483-444E7B96-1025@storefull-3254.bay.webtv.net> <124t6thopj1pea7@corp.supernews.com> Roy Lewallen wrote: > What's it's velocity factor, and how did you calculate it? I can't believe I did that! It must be from spending too much time reading Internet postings. Of course I meant: > What's its velocity factor, and how did you calculate it? ^^^ I knew better than that by the time I'd finished grade school. Hope it isn't all downhill from here. Roy Lewallen, W7EL Article: 223817 of rec.radio.amateur.antenna From: "Dr.Death" Subject: Re: I blame the ARRL for all the homosexual posts. Please Read. Date: Tue, 25 Apr 2006 19:23:08 -0500 Message-ID: <124tfbo3tags68c@corp.supernews.com> References: "Steve N." wrote in message news:e2ltri$dnr$1@avnika.corp.mot.com... > Chill guys. Think a moment...Who's the lame of mind here. The OP with 1 > post or the 60 responses... Looks like he suckered y'all in and had the > desired effect > 73, Steve, K9DCI > > "Skirt Chaser" > > **** NOTE: his brain dont [sic] either... > > Make that 61 with your response. BTW, Skirt Chaser is also known as Slow Code, a supposed ham that is too cowardly to include his call sign. Article: 223818 of rec.radio.amateur.antenna From: Buck Subject: Re: J_Pole Trials and Tribulations Message-ID: <4tjt42lg6k5ustfmiljfkpiqdle084d0iq@4ax.com> References: <1146008591.641742.237030@y43g2000cwc.googlegroups.com> Date: Tue, 25 Apr 2006 21:42:49 -0400 On 25 Apr 2006 16:43:11 -0700, jgboyles@aol.com wrote: > >jimbo wrote: SNIP >> jimbo - AJ7IM > > Hi Jimbo, it has been my experience, and everybody else's that an >indoor or attic J-pole is unpredictable. A high impedance end fed >antenna in an attic environment will be hard to predict. Moving it one >foot can effect things. > You might consider the SO-239 ground plane. It can be built and >tuned in 30 minutes, is 50 ohms, so it will not be so concerned about >its environment. Likely you could not tell a difference in performance >from a J-pole especially if they are both in the attic. > Oh yes, the standard-if the SWR is below 3.0, don't worry about it. >Gary N4AST I started building dipole antennas. they can be mounted horizontal or vertical and easily moved around. I use cpvc with a dipole wire inside and a coax-choke balun. They work quite well. Just another option. -- 73 for now Buck N4PGW Article: 223819 of rec.radio.amateur.antenna From: "jimmiefender@bellsouth.net" References: Subject: Re: mobile loading coils Message-ID: Date: Tue, 25 Apr 2006 23:24:47 -0400 "Buck" wrote in message news:t9jo4219dvidni11gkp8gqjljnie2ct12h@4ax.com... > >> I went to the Home Depot today and found some chimney sweeper brush >> handles >>. These are about 4 ft long each made of fiberglass and screw together. A >>few of these in the back of the truck will allow me to put together nearly >>any length antenna I need. Im thinking 40M may be a practical limit Dont >>worry I dont drive and ham at the same time. >> > > how much were the sweeper handles? > > -- > 73 for now > Buck > N4PGW Buck, when I saw them there wasnt a price on the handles so I went back today to check. All of the chimney sweep items were gone. I checked and found that these items are seasonal and wont be back out until August or September, day late and a dollar short. It doesnt make sense to me, this is the time of year that they should be out. I have never cleaned a chimney but have had it done and you dont do it during the heating season. Oh well, I still think these have great possibilities as antenna parts barring they dont turn out to be super expensive. Jimmie Article: 223820 of rec.radio.amateur.antenna From: "west" Subject: Coax Bulkhead Message-ID: Date: Wed, 26 Apr 2006 04:12:09 GMT Is there a place on the net, in a book, etc. that I can see examples & diagrams of a coax bulkhead? My house sits on a slab and I want to run about 4 or 5 coax cables, rotor cable, AC & DC source all going from the shack to my tower. In Florida lightning is a major concern so the bulkhead will have to have coax & other type of arrestors. All this is grounded to a copper ground rod & the cables, of course, to my shack. I would like this outside "box" nicely & neatly dressed & labeled so it's easy to disconnect & not an eye sore. I searched the Ham books and many Internet sights to no avail. Anybody? Thank you. west, AF4GC Article: 223821 of rec.radio.amateur.antenna From: "Sal M. Onella" References: Subject: Re: J_Pole Trials and Tribulations Message-ID: Date: Tue, 25 Apr 2006 22:32:36 -0700 "jimbo" wrote in message news:cq2dnXJUtOYYCtPZnZ2dnUVZ_tednZ2d@comcast.com... > I have been trying to get an acceptable 2 meter antenna installed in > my attic. A J-Pole seemed to me the best solution for my attic space. > You may recall an earlier post where I discussed SWR on one of the > ladder line J-Poles I was working with. Well, I gave up on ladder line > and constructed a J-Pole from 1/2 inch copper tubing. I tuned it in my > basement work shop to give the best SWR and then took it up to the > attic. The following table shows the results. > > Basement Attic > > 144 1.90 1.80 > 145 1.65 2.00 > 146 1.50 2.10 > 147 1.60 2.25 > 147.995 1.90 2.25 > > Actually, probably not that bad for a first attempt at copper tubing. > But, I didn't like the fact that SWR was above 2.0 in my attic and > that things changed between my basement shop and the attic. I guess > this design is influenced by objects close by. > > So, somewhere in my surfing I came across the Arrow J-Pole. This is an > end fed, open stub commercial design that promises less that 1.5 SWR > across the band. Here are the results of my experiment with this antenna. > > Basement Attic > > 144 1.10 1.22 > 145 1.18 1.10 > 146 1.25 1.20 > 147 1.30 1.32 > 147.995 1.40 1.42 > > Not 1.0 SWR but certainly met the promise. And the best thing about > this design is that near by objects don't seem to have an impact on > performance. If I built one of these designs and tuned it in my > basement shop, it should give the same results in the attic. > > Anyway, just my subjective observations. > Not to detract from the other posters ... IMO they all made valid comments, but I offer this: As the builder of about 20 copper pipe j-poles, I discovered that I can get a better final VSWR if I include a 100 pF (or so) cap in the side fed by the coax center. I had been attaching an SO-239-type bulkhead connector to the short side of the J and running a piece of solid wire from the center pin over to the long side of the J. I could get the VSWR to a dip near the middle of the band by monkeying with the feed point and/or trimming the length but the lowest I usually got was around 1.5 : 1. As soon as I used the cap in place of the straight wire, I could get 1:1. It works for me ... your mileage may vary. I built more j-poles for 2M than all the others combined and 20 is not a lot of antennas. For some reason, the cap seems to help the 2M size more than it helps the others, but these antennas are too few in number for scientific judgements by this amateur plumber. 73, John Article: 223822 of rec.radio.amateur.antenna From: "Jeff" Subject: Re: Coax Bulkhead Date: Wed, 26 Apr 2006 08:08:49 +0100 Message-ID: References: I would try the connector manufacturers' websites, such as Amphenol, Radial, Schuner, etc, and perhaps Polyphaser for arrestors. Regards Jeff "west" wrote in message news:tqC3g.1800$%x.1050@tornado.tampabay.rr.com... > Is there a place on the net, in a book, etc. that I can see examples & > diagrams of a coax bulkhead? My house sits on a slab and I want to run > about > 4 or 5 coax cables, rotor cable, AC & DC source all going from the shack > to > my tower. In Florida lightning is a major concern so the bulkhead will > have > to have coax & other type of arrestors. All this is grounded to a copper > ground rod & the cables, of course, to my shack. I would like this outside > "box" nicely & neatly dressed & labeled so it's easy to disconnect & not > an > eye sore. I searched the Ham books and many Internet sights to no avail. > Anybody? Thank you. > > west, AF4GC > > Article: 223823 of rec.radio.amateur.antenna From: Buck Subject: Re: Coax Bulkhead Message-ID: References: Date: Wed, 26 Apr 2006 06:05:21 -0400 On Wed, 26 Apr 2006 04:12:09 GMT, "west" wrote: >Is there a place on the net, in a book, etc. that I can see examples & >diagrams of a coax bulkhead? My house sits on a slab and I want to run about >4 or 5 coax cables, rotor cable, AC & DC source all going from the shack to >my tower. In Florida lightning is a major concern so the bulkhead will have >to have coax & other type of arrestors. All this is grounded to a copper >ground rod & the cables, of course, to my shack. I would like this outside >"box" nicely & neatly dressed & labeled so it's easy to disconnect & not an >eye sore. I searched the Ham books and many Internet sights to no avail. >Anybody? Thank you. > >west, AF4GC > Don't use the 'gap' type arrestors for the antenna feeds. They look great, but by the time the spark jumps, it will have fried your finals. Use the gas types where the charge is arrested more quickly than the gap styles. -- 73 for now Buck N4PGW Article: 223824 of rec.radio.amateur.antenna From: John Ferrell Subject: Re: Lightning protection Message-ID: References: Date: Wed, 26 Apr 2006 13:45:36 GMT I think most of us choose to ignore risks that are beyond our perceived control. We have some pretty violent storm activity in the area I live (central North Carolina) but death and structure damage seem to be rare. Most of the time the human body represents a higher impedance path than its surroundings. On the other hand, electronic property damage is common. It seems to go with certain locations. I live in one of those locations and I have taken all of the precautions I can think of over the winter months. We have had a couple of storms in the past week without noticeable damage. I am certain that the house took a hit on Saturday morning on the new lightning rod system at the east end of the structure. It sounded different than the usual damaging strike. It was more of a drawn out event (half a second or so) than the damaging explosive sound. I am speculating of course. Last night a less threatening storm came through with no damage noted. However I have two Labrador Retriever dogs, "Shadow" an 85 pound black female that is especially smart, and "Bear" 130 pounds of white macho male. Shadow always takes refuge in the bath tub and Bear gets as close to me as he can for a storm. Last night I spent two hours on the floor comforting Bear during the storm and wondering if the dogs might simply be smarter than I! I have had strikes in the past that resulted in "fireballs" bouncing through the room. The dogs came by the fear as a result. IMHO, the difference between bravery and stupidity is how you choose to perceive it! On a more positive note, I worked Italy, Spain, Wales and Poland on 20 meters yesterday afternoon with my new TenTec Jupiter transceiver. I believe this little ridge is a very good radio location... de W8CCW John On Wed, 26 Apr 2006 11:50:05 +0100, "Reg Edwards" wrote: >There is much correspondence on these walls about protecting equipment >and property from lightning strikes. But there is never anything said >about protecting people. Where are your concerns? > >In this country, UK, I can't remember the last time I read in the >newspaper about anybody being killed by lightning. It is extremely >rare. > >It doesn't appear to give US citizens much cause for concern. Are you >all very brave? Or have you just got used to it. > >Just curious. What is the annual death rate due to lightning, per head >of population, in states like Florida? Do you keep statistics? > >How does it compare with the death rate from being chewed to death by >alligators in Florida swamps? Or dying from rattlesnake bites in >Arizona? Does lightning make it to the newspapers? >---- >Reg. > John Ferrell W8CCW Article: 223825 of rec.radio.amateur.antenna From: Buck Subject: Re: Lightning protection Message-ID: References: Date: Wed, 26 Apr 2006 10:17:18 -0400 On Wed, 26 Apr 2006 11:50:05 +0100, "Reg Edwards" wrote: >There is much correspondence on these walls about protecting equipment >and property from lightning strikes. But there is never anything said >about protecting people. Where are your concerns? > >In this country, UK, I can't remember the last time I read in the >newspaper about anybody being killed by lightning. It is extremely >rare. > >It doesn't appear to give US citizens much cause for concern. Are you >all very brave? Or have you just got used to it. > >Just curious. What is the annual death rate due to lightning, per head >of population, in states like Florida? Do you keep statistics? > >How does it compare with the death rate from being chewed to death by >alligators in Florida swamps? Or dying from rattlesnake bites in >Arizona? Does lightning make it to the newspapers? >---- >Reg. > Lightening deaths are part of the Darwin Award system. A group of lawyers were fishing in a row-boat when a storm came up. One raised his fishing pole and shouted, "Alright, God, take your best shot!" They buried him shortly afterwards. Lightening dangers are taught in schools from pre-school through high school. Most people know that when lightening is in the area, to get to cover, therefore, there is a lack of fatalities. However, there are some caught unaware as lightening can precede a storm by as much as 10-15 miles and some people don't realize that and stay vulnerable. Lightening deaths are reported, but I don't think they will ever make the national news unless it is a celebrity or at some really prestigious event. -- 73 for now Buck N4PGW Article: 223826 of rec.radio.amateur.antenna From: "Peter O. Brackett" References: Subject: Re: Lightning protection Message-ID: Date: Wed, 26 Apr 2006 15:01:51 GMT Reg: Every year there are a few reports of people struck by and often killed by lightning. Indeed Florida is the leading place in the whole world for lightning activity and lightning deaths. In Florida we have really vicious thunderstorm activity throughout the summer months. These storms come up fast, thunderheads rising upwards of 50,000 feet, with black wall clouds decending to ground level and the air thick with static and rain so hard that you cannot see more than 25 feet. Impressive stuff! I have never personally met anyone who was struck by lightning. One of my own [arbitrary length] dipoles was simply vaporized by a strike when I was not at home... the ladder line that fed it's center was also missing and there was a two foot diameter hole about a foot deep in the lawn where I had left the end of the line laying on the ground. That's where I place the ladder line when not in the shack. When I returned home after that storm, I found the rope ends at the two supports simply swinging in the wind with the insulators on the ends still intact. During the annual ARRL Field Day event, held at the peak of Florida lightning season, in June of each year, I/we quickly disconnect feedlines and throw them well away from the transmitter sites during thunderstorm approach, on several occasions during those Field Days, and from a distance and under appropriate shelter, I have personally watched arcs jumping across the air gap between the conductors of the end of ladder line lying on the ground during the passage of thunderclouds. But I have never witnessed an actual strike on one of those antennas. I don't have statistics at hand, but I can relay that most of the news reports of lightning deaths that I recall here in Florida were of the deaths of unfortunate golfers who failed to take shelter during a thunderstorm approach. I do recall a news report of someone killed by lightning on a Florida beach within the past couple of years. It would be my guess that most who are struck by lightning in Florida are visitors... As far as I can tell, most folks who live in Florida year round are very well aware of the dangers of lightning and take appropriate cautions. -- Pete k1po Indialantic By-the-Sea, FL "Reg Edwards" wrote in message news:S_2dnbu5se51zdLZRVnyug@bt.com... > There is much correspondence on these walls about protecting equipment > and property from lightning strikes. But there is never anything said > about protecting people. Where are your concerns? > > In this country, UK, I can't remember the last time I read in the > newspaper about anybody being killed by lightning. It is extremely > rare. > > It doesn't appear to give US citizens much cause for concern. Are you > all very brave? Or have you just got used to it. > > Just curious. What is the annual death rate due to lightning, per head > of population, in states like Florida? Do you keep statistics? > > How does it compare with the death rate from being chewed to death by > alligators in Florida swamps? Or dying from rattlesnake bites in > Arizona? Does lightning make it to the newspapers? > ---- > Reg. > > Article: 223827 of rec.radio.amateur.antenna From: Allisonnospam@nouce.bellatlantic.net Subject: Re: J_Pole Trials and Tribulations Message-ID: References: Date: Wed, 26 Apr 2006 16:13:43 GMT On Wed, 26 Apr 2006 09:14:24 -0600, jimbo wrote: >jimbo wrote: >> I have been trying to get an acceptable 2 meter antenna installed in my >> attic. A J-Pole seemed to me the best solution for my attic space. You >> may recall an earlier post where I discussed SWR on one of the ladder >> line J-Poles I was working with. Well, I gave up on ladder line and >> constructed a J-Pole from 1/2 inch copper tubing. I tuned it in my >> basement work shop to give the best SWR and then took it up to the >> attic. The following table shows the results. >> >> Basement Attic >> >> 144 1.90 1.80 >> 145 1.65 2.00 >> 146 1.50 2.10 >> 147 1.60 2.25 >> 147.995 1.90 2.25 >> >> Actually, probably not that bad for a first attempt at copper tubing. >> But, I didn't like the fact that SWR was above 2.0 in my attic and that >> things changed between my basement shop and the attic. I guess this >> design is influenced by objects close by. >> >> So, somewhere in my surfing I came across the Arrow J-Pole. This is an >> end fed, open stub commercial design that promises less that 1.5 SWR >> across the band. Here are the results of my experiment with this antenna. >> >> Basement Attic >> >> 144 1.10 1.22 >> 145 1.18 1.10 >> 146 1.25 1.20 >> 147 1.30 1.32 >> 147.995 1.40 1.42 >> >> Not 1.0 SWR but certainly met the promise. And the best thing about this >> design is that near by objects don't seem to have an impact on >> performance. If I built one of these designs and tuned it in my basement >> shop, it should give the same results in the attic. >> >> Anyway, just my subjective observations. >> >> jimbo - AJ7IM > >I guess my conclusion is that the conventional J-Pole design seems to >be more susceptible to near by objects than the much less common end >fed, open stub, J-Pole. My conventional copper J-pole changed much >more than the end fed Arrow J-Pole when moved from the basement to the >attic. And I have noticed on other occasions that even very small >changes in location and/or orientation had a large effect on SWR. I happen to have and use both, copper Jpole and Arrow OSJ146/440. The copper when setup in an open space (more than 12ft from anything and atleast 6ft high) not only has the same SWR inband but behaves the same (swr increases) if near the house or other objects. About the only real difference is the OSJ is pretuned and very wideband and the copper had to be tuned correctly first. The fact that both show increasing SWR with frequency says that in the attic they appear to be too long. I had a similar problem with a 10m antenna here in the attic and hard to prune it 3% shorter than one out in the yard. At 2m that would be at least 1" shorter. The fact that your seeing an SWR from the Arrow in the attic shows the interaction as the two I use for base and field ops never show SWR above 1.2:1 (using short lowloss cables). >The ARRL Antenna Book has a small section on J-Pole antennas. They >show both designs, conventional shorted stub and the uncommon end fed, >open stub designs. They say that the shorted stub design should have a >4/1 balun at the feed point because a direct coax connection results >in extreme sensitivity to near by objects. And they also say the end >fed, open stub design doesn't require a balun and is much less >sensitive to near by objects, but is harder to tune. (I don't >understand that point, there is one less parameter to fiddle with.) Bah foo. The feed point can have any impedence by adjusting the tap point. However the stubbed copper Jpole is really a balanced feed though when correctly tuned there is minimal interaction if the feed is unbalanced. The problem is if it's not correctly tuned the interaction is quite pronounced. One trick I've used that makes the cable interaction less pronounced is to feed with a bazooka (1:1) or ferrite current balun so the cable position and lack of balanced feed are not interacting. makes setting the tap point and then tuning the length far easier. >All of this leads me to wonder why almost all J-Pole designs one sees >are of the shorted stub version and almost none use a balun. I suspect >ease of construction and low cost. My "store bought" Arrow end fed, Stub fed is a DC short and makes grounding easier. Open feed you need a polyphasor or other lightining protection device on the coax. >open stub, J-Pole seems to verify the ARRL Antenna Book's conclusions >about sensitivity to near by objects. However, do-it-yourself >construction does appear to be much more difficult. I may give it a >try, just out of curiosity. You can effect the match with either open or shorted stubs when the dimensions are correct. Performance is not significantly different. See Mr Cebiks site. He has done a lot of work that is more fact than lore. >A final note. My attic is a very difficult place to work. There is no >way I can install an antenna and then make numerous adjustments to get >it tuned to the space. I must be able to do any required tuning in my >basement shop or maybe outside on my deck and then take it to the >attic for installation. So for my application, I want something that >is not sensitive to near by objects. The end fed, open stub J-Pole >seems to fit that requirement. An attic is a problem for many antennas and tuning them is part of it. One trick I've tried to help others was tune it inside a room and then note how the SWR changes in location and adjust accordingly. Tuning in this case was adjusting the length of the longer element (capped with 1/.4" brass bolt and nut) and stub length without altering the initial best SWR tap. Usually shortening the longer element was the needed adjustment. Allison Article: 223828 of rec.radio.amateur.antenna From: "Tom Donaly" Subject: Re: Lightning protection References: Message-ID: Date: Wed, 26 Apr 2006 16:17:32 GMT Peter O. Brackett wrote: > Reg: > > Every year there are a few reports of people struck by and often killed by > lightning. > > Indeed Florida is the leading place in the whole world for lightning > activity and lightning deaths. > > In Florida we have really vicious thunderstorm activity throughout the > summer months. These storms come up fast, thunderheads rising upwards of > 50,000 feet, with black wall clouds decending to ground level and the air > thick with static and rain so hard that you cannot see more than 25 feet. > Impressive stuff! > > I have never personally met anyone who was struck by lightning. > > One of my own [arbitrary length] dipoles was simply vaporized by a strike > when I was not at home... the ladder line that fed it's center was also > missing and there was a two foot diameter hole about a foot deep in the lawn > where I had left the end of the line laying on the ground. That's where I > place the ladder line when not in the shack. When I returned home after > that storm, I found the rope ends at the two supports simply swinging in the > wind with the insulators on the ends still intact. During the annual ARRL > Field Day event, held at the peak of Florida lightning season, in June of > each year, I/we quickly disconnect feedlines and throw them well away from > the transmitter sites during thunderstorm approach, on several occasions > during those Field Days, and from a distance and under appropriate shelter, > I have personally watched arcs jumping across the air gap between the > conductors of the end of ladder line lying on the ground during the passage > of thunderclouds. But I have never witnessed an actual strike on one of > those antennas. > > I don't have statistics at hand, but I can relay that most of the news > reports of lightning deaths that I recall here in Florida were of the deaths > of unfortunate golfers who failed to take shelter during a thunderstorm > approach. I do recall a news report of someone killed by lightning on a > Florida beach within the past couple of years. > > It would be my guess that most who are struck by lightning in Florida are > visitors... As far as I can tell, most folks who live in Florida year round > are very well aware of the dangers of lightning and take appropriate > cautions. > > -- > Pete k1po > Indialantic By-the-Sea, FL > > > "Reg Edwards" wrote in message > news:S_2dnbu5se51zdLZRVnyug@bt.com... > >>There is much correspondence on these walls about protecting equipment >>and property from lightning strikes. But there is never anything said >>about protecting people. Where are your concerns? >> >>In this country, UK, I can't remember the last time I read in the >>newspaper about anybody being killed by lightning. It is extremely >>rare. >> >>It doesn't appear to give US citizens much cause for concern. Are you >>all very brave? Or have you just got used to it. >> >>Just curious. What is the annual death rate due to lightning, per head >>of population, in states like Florida? Do you keep statistics? >> >>How does it compare with the death rate from being chewed to death by >>alligators in Florida swamps? Or dying from rattlesnake bites in >>Arizona? Does lightning make it to the newspapers? >>---- >>Reg. >> >> > > > But are the thunderclouds lumped elements or transmission lines, peter? 73, Tom Donaly, KA6RUH Article: 223829 of rec.radio.amateur.antenna From: "Peter O. Brackett" References: Subject: Re: Lightning protection Message-ID: Date: Wed, 26 Apr 2006 16:24:23 GMT Hi Tom: Hmmm... Thunderclouds, lumped or distributed? It all depends upon the application requirments... if the occurence is infrequent one may make a quasi-static assumption and invoke DC conditions. Then we can make an approximation and treat the lightning stroke just as a DC conductor. Now... Just what is the steady state DC value for a lightning stroke? Ignoring the parasitic capacitance between strokes... we can approximate it as a long vertical wire, without loading... Then... Well you get the picture [grin]. Incidently we are in a very unusual dry spell here on the barrier island off Florida's East coast... we have only had about 1/8 inch of rain in the past three months, and the whole County is on fire! Regards, -- Pete k1po Indialantic By-the-Sea, FL "Tom Donaly" wrote in message news:w2N3g.20544$tN3.13487@newssvr27.news.prodigy.net... > Peter O. Brackett wrote: >> Reg: >> >> Every year there are a few reports of people struck by and often killed >> by lightning. >> >> Indeed Florida is the leading place in the whole world for lightning >> activity and lightning deaths. >> >> In Florida we have really vicious thunderstorm activity throughout the >> summer months. These storms come up fast, thunderheads rising upwards of >> 50,000 feet, with black wall clouds decending to ground level and the air >> thick with static and rain so hard that you cannot see more than 25 feet. >> Impressive stuff! >> >> I have never personally met anyone who was struck by lightning. >> >> One of my own [arbitrary length] dipoles was simply vaporized by a strike >> when I was not at home... the ladder line that fed it's center was also >> missing and there was a two foot diameter hole about a foot deep in the >> lawn where I had left the end of the line laying on the ground. That's >> where I place the ladder line when not in the shack. When I returned >> home after that storm, I found the rope ends at the two supports simply >> swinging in the wind with the insulators on the ends still intact. >> During the annual ARRL Field Day event, held at the peak of Florida >> lightning season, in June of each year, I/we quickly disconnect feedlines >> and throw them well away from the transmitter sites during thunderstorm >> approach, on several occasions during those Field Days, and from a >> distance and under appropriate shelter, I have personally watched arcs >> jumping across the air gap between the conductors of the end of ladder >> line lying on the ground during the passage of thunderclouds. But I have >> never witnessed an actual strike on one of those antennas. >> >> I don't have statistics at hand, but I can relay that most of the news >> reports of lightning deaths that I recall here in Florida were of the >> deaths of unfortunate golfers who failed to take shelter during a >> thunderstorm approach. I do recall a news report of someone killed by >> lightning on a Florida beach within the past couple of years. >> >> It would be my guess that most who are struck by lightning in Florida are >> visitors... As far as I can tell, most folks who live in Florida year >> round are very well aware of the dangers of lightning and take >> appropriate cautions. >> >> -- >> Pete k1po >> Indialantic By-the-Sea, FL >> >> >> "Reg Edwards" wrote in message >> news:S_2dnbu5se51zdLZRVnyug@bt.com... >> >>>There is much correspondence on these walls about protecting equipment >>>and property from lightning strikes. But there is never anything said >>>about protecting people. Where are your concerns? >>> >>>In this country, UK, I can't remember the last time I read in the >>>newspaper about anybody being killed by lightning. It is extremely >>>rare. >>> >>>It doesn't appear to give US citizens much cause for concern. Are you >>>all very brave? Or have you just got used to it. >>> >>>Just curious. What is the annual death rate due to lightning, per head >>>of population, in states like Florida? Do you keep statistics? >>> >>>How does it compare with the death rate from being chewed to death by >>>alligators in Florida swamps? Or dying from rattlesnake bites in >>>Arizona? Does lightning make it to the newspapers? >>>---- >>>Reg. >>> >>> >> >> >> > > But are the thunderclouds lumped elements or transmission lines, > peter? > 73, > Tom Donaly, KA6RUH Article: 223830 of rec.radio.amateur.antenna From: richardharrison@webtv.net (Richard Harrison) Subject: Re: Velocity Factor and resonant frequency Date: Wed, 26 Apr 2006 11:43:18 -0500 Message-ID: <6547-444FA326-76@storefull-3255.bay.webtv.net> References: <124t6thopj1pea7@corp.supernews.com> Roy, W7EL wrote: "What is the velocity factor, and how did you calculate it?" Given: length = 12 inches diamwter = 6 in. L = 38.6 microhenry I used formula (37) from Terman`s Handbook to calculate 25 turns in the coil. 471 inches of wire are needed in the coil. The velocity of the EM wave traveling around the turns of the coil is almost equal to the velocity in a straight wire. But, the time required to travel 471 inches is 40 times the time required to travel 12 inches. The velocity factor is the reciprocal of 40 or 0.025. Best regards, Richard Harrison, KB5WZI Article: 223831 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Velocity Factor and resonant frequency References: <124qfaq4636hq11@corp.supernews.com> <6O2dnfHF5slNzdDZnZ2dnUVZ8tKdnZ2d@bt.com> <124qlp7fe41g87a@corp.supernews.com> <1145927357.742041.218170@v46g2000cwv.googlegroups.com> <444e1403$0$1012$39cecf19@news.twtelecom.net> <444e30da$0$1012$39cecf19@news.twtelecom.net> <444e399e$0$1007$39cecf19@news.twtelecom.net> <444e6790$0$1007$39cecf19@news.twtelecom.net> Message-ID: Date: Wed, 26 Apr 2006 17:07:36 GMT Tom Ring wrote: > Cecil Moore wrote: >> Let's say we have a 1/2WL dipole in free space driven by a >> self-contained source at the center. If we float a florescent >> light bulb around the ends of the dipole, are you saying the >> electric fields won't fire the bulb like it does on earth? > > Stop acting like an idiot Cecil. It was a technical question. I was just wondering what keeps the wire from transferring energy when it is located in free space. -- 73, Cecil http://www.qsl.net/w5dxp Article: 223832 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Velocity Factor and resonant frequency References: <8483-444E7B96-1025@storefull-3254.bay.webtv.net> <124t6thopj1pea7@corp.supernews.com> Message-ID: Date: Wed, 26 Apr 2006 17:34:14 GMT Roy Lewallen wrote: > That's all very nice. Let's see if it's useful for anything. > > A while back, Cecil posted a model of a base loaded vertical antenna. It > has an inductor which is vertically oriented. The bottom of the inductor > is 1 foot from the ground and the inductor is 1 foot long and six inches > in diameter. Inductance is 38.5 uH and it's self resonant at 13.48 MHz. > (Moving it very far from ground changes the resonant frequency to 13.52 > MHz.) > > What's it's velocity factor, and how did you calculate it? 13.48 MHz is not exactly the self-resonant frequency of the coil. At 13.48 MHz, the one foot bottom section is 0.0137 wavelengths long, i.e. 4.9 degrees. So the coil occupies 85.1 degrees, i.e. 0.236 wavelength. The coil length is coincidentally also one foot so the velocity factor is 4.9/85.1 = 0.058. -- 73, Cecil http://www.qsl.net/w5dxp Article: 223833 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Velocity Factor and resonant frequency References: <124t6thopj1pea7@corp.supernews.com> <6547-444FA326-76@storefull-3255.bay.webtv.net> Message-ID: Date: Wed, 26 Apr 2006 17:42:48 GMT Richard Harrison wrote: > Roy, W7EL wrote: > "What is the velocity factor, and how did you calculate it?" > > Given: > length = 12 inches > diamwter = 6 in. > L = 38.6 microhenry > > I used formula (37) from Terman`s Handbook to calculate 25 turns in the > coil. 471 inches of wire are needed in the coil. > > The velocity of the EM wave traveling around the turns of the coil is > almost equal to the velocity in a straight wire. But, the time required > to travel 471 inches is 40 times the time required to travel 12 inches. > The velocity factor is the reciprocal of 40 or 0.025. 13.48 MHz is not exactly the self-resonant frequency of the coil. At 13.48 MHz, the one foot bottom section is 0.0137 wavelengths long, i.e. 4.9 degrees. So the coil occupies ~85.1 degrees at self-resonance. The coil length is coincidentally also one foot so the velocity factor is 4.9/85.1 = 0.058. I don't have the Terman Handbook. Does he take adjacent coil coupling into account in that formula? If not, that's the difference in the two results. In either case, the velocity factor is not anywhere near 1.0 as the lumped circuit model would have us believe. Does anyone have a formula for what percentage of current is induced in coils farther and farther away from the primary coil? I haven't found such a formula in my references but it's got to exist. -- 73, Cecil http://www.qsl.net/w5dxp Article: 223834 of rec.radio.amateur.antenna From: dplatt@radagast.org (Dave Platt) Subject: Re: Lightning protection Date: Wed, 26 Apr 2006 18:22:52 -0000 Message-ID: <124vejss2fc1n42@corp.supernews.com> References: In article , Peter O. Brackett wrote: >> But are the thunderclouds lumped elements or transmission lines, >> peter? >Hmmm... Thunderclouds, lumped or distributed? It all depends upon the >application requirments... if the occurence is infrequent one may make a >quasi-static assumption and invoke DC conditions. I suspect that they're more correctly modelled as resonant circuits... specifically, as quartz-crystal oscillators. I keep hearing pilots talk about "clouds full of rocks"... -- Dave Platt AE6EO Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior I do _not_ wish to receive unsolicited commercial email, and I will boycott any company which has the gall to send me such ads! Article: 223835 of rec.radio.amateur.antenna From: richardharrison@webtv.net (Richard Harrison) Subject: Re: Velocity Factor and resonant frequency Date: Wed, 26 Apr 2006 15:05:48 -0500 Message-ID: <8655-444FD29C-109@storefull-3253.bay.webtv.net> References: Cecil, W5DXP wrote: "I don`t have the Terman Handbook." Formula (37) on page 55 of the 1943 "Radio Engineers` Handbook is: Lo = (r sq) (n sq) / 9(r) + 10(l) Lo = approximate low-frequency inductance of a single-layer solenoid in microhenries where r is the radius and l is the length of the coil in inches. Terman attributes the formula to H.A. Wheeler, "Simple Inductance Formulas for Radio Coils", Proc. I.R.E., Vol 16, P1398, October 1928. Best regards, Richard Harrison, KB5WZI Article: 223836 of rec.radio.amateur.antenna From: Owen Duffy Subject: Re: Lightning protection Message-ID: References: Date: Wed, 26 Apr 2006 21:12:31 GMT On Wed, 26 Apr 2006 11:50:05 +0100, "Reg Edwards" wrote: >There is much correspondence on these walls about protecting equipment >and property from lightning strikes. But there is never anything said >about protecting people. Where are your concerns? ... What on earth made you think that hams are generally safety conscious? >From my experience, I suggest that most place little value on safety (fire safety, electrical safety, safe working at heights, safe vehicular installations, protecting immediate family and other would be rescuers from risk in the event of an accident). I am not saying that no one does it, just very few. A walk around most amateur stations reveals uncontrolled hazards. And the statistics say that the probability of adverse outcome is low. So in an unconscious risk managed approach, it seems most people assess that "it won't happen to me". Owen PS: there are standards or codes that relate to lightning and electrical hazards in most modern jurisdictions, but amateurs seem rarely familiar with them, and to the extent that there is any compliance, it is entirely accidental and unintended. -- Article: 223837 of rec.radio.amateur.antenna From: "Frank" References: Subject: Re: Lightning protection Message-ID: Date: Thu, 27 Apr 2006 02:33:16 GMT "Reg Edwards" wrote in message news:S_2dnbu5se51zdLZRVnyug@bt.com... > There is much correspondence on these walls about protecting equipment > and property from lightning strikes. But there is never anything said > about protecting people. Where are your concerns? > > In this country, UK, I can't remember the last time I read in the > newspaper about anybody being killed by lightning. It is extremely > rare. > > It doesn't appear to give US citizens much cause for concern. Are you > all very brave? Or have you just got used to it. > > Just curious. What is the annual death rate due to lightning, per head > of population, in states like Florida? Do you keep statistics? > > How does it compare with the death rate from being chewed to death by > alligators in Florida swamps? Or dying from rattlesnake bites in > Arizona? Does lightning make it to the newspapers? > ---- > Reg. http://www.torro.org.uk/TORRO/research/lightning.php Article: 223838 of rec.radio.amateur.antenna Date: Wed, 26 Apr 2006 22:02:51 -0500 From: Tom Ring Subject: Re: Lightning protection References: Message-ID: <4450345b$0$1014$39cecf19@news.twtelecom.net> Frank wrote: > "Reg Edwards" wrote in message > news:S_2dnbu5se51zdLZRVnyug@bt.com... > >>There is much correspondence on these walls about protecting equipment >>and property from lightning strikes. But there is never anything said >>about protecting people. Where are your concerns? >> >>In this country, UK, I can't remember the last time I read in the >>newspaper about anybody being killed by lightning. It is extremely >>rare. >> >>It doesn't appear to give US citizens much cause for concern. Are you >>all very brave? Or have you just got used to it. >> >>Just curious. What is the annual death rate due to lightning, per head >>of population, in states like Florida? Do you keep statistics? >> >>How does it compare with the death rate from being chewed to death by >>alligators in Florida swamps? Or dying from rattlesnake bites in >>Arizona? Does lightning make it to the newspapers? >>---- >>Reg. > > > http://www.torro.org.uk/TORRO/research/lightning.php > > Hmmm. Looks like ignorance is bliss, Reg. I would have human strikes and kills to be much lower in the UK than it is. Unless I totally misunderstand the weather patterns there vs. here, you couldn't possibly get the number of severe thunderstorms that we do in the US. So maybe we are more aware and better prepared. Although I could be quite mistaken in my beliefs. But I doubt it. tom K0TAR Article: 223839 of rec.radio.amateur.antenna From: Roy Lewallen Subject: Re: Multi hopping radio waves Date: Thu, 27 Apr 2006 00:54:44 -0700 Message-ID: <1250u68k0q1n13f@corp.supernews.com> References: Reg Edwards wrote: > ========================================= > It has just occurred to me that the loss due to ground reflections may > be related to the angle at which waves strike the earth. It is the > same angle as the transmit elevation angle and can be quite small. > ---- > Reg. The amplitude and phase of a field after ground reflection depends on the polarization, and is quite different for horizontal and vertical. It of course also depends on ground conductivity and permittivity, frequency, and angle. The equations are simple, and can be found in Kraus and other references. Those equations are used by NEC for determination of the far field pattern. Roy Lewallen, W7EL Article: 223840 of rec.radio.amateur.antenna From: Roy Lewallen Subject: Re: Multi hopping radio waves Date: Thu, 27 Apr 2006 03:01:44 -0700 Message-ID: <12515kccr5eo71f@corp.supernews.com> References: <1250u68k0q1n13f@corp.supernews.com> <7JSdnf1lbv9TGc3ZRVny2Q@bt.com> Reg Edwards wrote: >> The amplitude and phase of a field after ground reflection depends > on >> the polarization, and is quite different for horizontal and > vertical. It >> of course also depends on ground conductivity and permittivity, >> frequency, and angle. The equations are simple, and can be found in >> Kraus and other references. Those equations are used by NEC for >> determination of the far field pattern. >> >> Roy Lewallen, W7EL > > =========================================== > > Yes! But what's the ball park, rule-of-thumb value in dB ? > ---- > Reg I dunno. What's the ball park, rule-of-thumb value of a resistor in ohms? Roy Lewallen, W7EL Article: 223841 of rec.radio.amateur.antenna From: "Yuri Blanarovich" References: <1250u68k0q1n13f@corp.supernews.com> <7JSdnf1lbv9TGc3ZRVny2Q@bt.com> Subject: Re: Multi hopping radio waves Message-ID: Date: Thu, 27 Apr 2006 08:22:17 -0400 Uh, uh, Wait until Richard Clark sees this and descends on you!!! :-) Reg, you can't just look at HF waves propagation through simple "reflective" glasses. There is considerable amount of propagating going on by refraction, ducting, polarization gets all tumbled around and ground conditions vary so much that even those orderly, same current in a loading coil believers get drowned. There are some propagation prediction programs that will do some predicting +- 59%, but that's about it. Otherwise as W7EL says, if you are looking at the antenna pattern forming properties within few wavelengths you need to consider polarization and ground conditions within the zone, but once you get beyond "first hop" you are on the mercy of propagation Gods. You can look at my oooold article http://members.aol.com/ve3bmv/bmvpropagation.htm which at the time was judged "ridiculous" and "nothing new" at the same time. Now a days, especially low band crowds are coming around and admitting that there is perhaps more refracting/ducting than reflecting going on and trying to figure out when, why, how. W8JI fought another losing battle claiming that there is no high angle propagation on extreme DX signals on 160/80, or skewed path. Now he is "guru" on the subject. Soooo, depends.... what you are after? For "regular" conditions you can apply some ballparks, but for extreme DXing and weak signal comms, there is whole different world outside of formulas. Yuri K3BU, VE3BMV "Reg Edwards" wrote in message news:7JSdnf1lbv9TGc3ZRVny2Q@bt.com... >> The amplitude and phase of a field after ground reflection depends > on >> the polarization, and is quite different for horizontal and > vertical. It >> of course also depends on ground conductivity and permittivity, >> frequency, and angle. The equations are simple, and can be found in >> Kraus and other references. Those equations are used by NEC for >> determination of the far field pattern. >> >> Roy Lewallen, W7EL > > =========================================== > > Yes! But what's the ball park, rule-of-thumb value in dB ? > ---- > Reg > > Article: 223842 of rec.radio.amateur.antenna Date: Thu, 27 Apr 2006 09:30:29 -0400 From: jawod Subject: "interesting" antenna design Message-ID: <69488$4450c795$453d9423$12820@FUSE.NET> I was listening to 40M the other night and a reasonably clear SSB signal came from a guy in Pennsylvania using 100 W to a rain gutter. It was apparently raining at the time in PA. All the mathematical modeling and tweaking discussed in this group ... I thought the successful use of a rain gutter deserved some praise here. John AB8WH Article: 223843 of rec.radio.amateur.antenna From: "Frank" References: Subject: Re: Multi hopping radio waves Message-ID: Date: Thu, 27 Apr 2006 16:02:32 GMT "Reg Edwards" wrote in message news:csKdnWWJrarV9s3ZRVnysg@bt.com... > With multi-hops through the ionosphere there will be reflections from > the ground between adjacent hops. If there are N hops there will be > N-1 ground reflections. > > At each reflection a signal loss is incurred. But the ground is a > variable quantity. > > What rule of thumb relating to reflection loss is used by radio > professionals when calculating path loss? > > At the back of my mind I have a figure of 5 dB per reflection. Is this > in the right ball park? > > Thank you. > ---- > Reg. Reflection loss can vary from zero to infinity; depending on the material and angle of incidence. For example; take the oblique incidence of a horizontally polarized EM wave on an air/rocky ground interface of:: conductivity 2 mS/m, and relative permittivity 15. The reflection loss at zero degrees is 4.4 dB, increasing to 21.4 dB at the pseudo Brewster angle of 76 degrees, and 0 dB at 90 degrees. Ref. Advanced Engineering Electromagnetics, C. A. Balanis, pp 206 - 214. I have copies of the Mathcad calculations if anybody is interested. Frank Article: 223844 of rec.radio.amateur.antenna From: richardharrison@webtv.net (Richard Harrison) Subject: Re: Multi hopping radio waves Date: Thu, 27 Apr 2006 11:49:22 -0500 Message-ID: <19197-4450F612-273@storefull-3257.bay.webtv.net> References: Reg, G4FGQ wrote: "At the back of my mind I have a figure of 5 dB per reflection. Is this the right ball park?" It could be right for some reflections. E.A. Laport was Chief Engineer of RCA International when he wrote "Radio Antenna Engineering". On page 236 Fig. 3.17 shows the effect of ground conductivity on maximum field strength from a horizontal dipole antenna versus its height in vavelengths. Optimum height would be about 0,50 wavelength to most concentrate energy at a certain vertical angle, 30-degrees according to the RAF Signal Manual quoted by Laport. 30-degrees might hop 1000 kilometers. At the antenna earth reflection point, frequencies between 2 and 16 MHz are reduced to 95% of their prereflection field strengths by ordinary soil from a dipole at 1/2-wavelength height. A reduction to 70.7% of prereflection strength would represent a 3 dB power loss. So no harm done yet by the reflection from an antenna over good soil. Lower antenna height and poorer soil would attenuate more. The angle at which rhe signal strikes the earth in subsequent reflections should be the same as the first reflection from the antenna. Conductivity and dielectric constant at subsequent earth reflection points are what they are. Shortwave broadcasters use vertically stacked horizontal elements to concentrate the vertical beam to avoid multipath interference. They also prefer targets reached on the first reflection from the ionosphere.. Best regards, Richard Harrison, KB5WZI Article: 223845 of rec.radio.amateur.antenna From: "Reg Edwards" References: Subject: Re: Multi hopping radio waves Date: Thu, 27 Apr 2006 18:17:18 +0100 Message-ID: > Reflection loss can vary from zero to infinity; depending on the material > and angle of incidence. ==================================== Yes I know. That's obvious. But what I would like to know is a typical or average value, or a range of most likely expected values found in practice. Some experienced person must know! Needed to crudely ESTIMATE ionospheric multi-hop path loss. Ground reflection losses are a small proportion of the total path loss but not small enough to be neglected. Just a whole number of decibels per reflection will do please. --- Reg. Article: 223846 of rec.radio.amateur.antenna From: "Frank" References: Subject: Re: Multi hopping radio waves Message-ID: Date: Thu, 27 Apr 2006 17:51:28 GMT "Reg Edwards" wrote in message news:oJCdnfRix8SyYM3ZRVnyig@bt.com... >> Reflection loss can vary from zero to infinity; depending on the > material >> and angle of incidence. > ==================================== > > Yes I know. That's obvious. > > But what I would like to know is a typical or average value, or a > range of most likely expected values found in practice. Some > experienced person must know! > > Needed to crudely ESTIMATE ionospheric multi-hop path loss. > > Ground reflection losses are a small proportion of the total path loss > but not small enough to be neglected. > > Just a whole number of decibels per reflection will do please. > --- > Reg. Some approximate examples at 7 MHz with angles of incidence >from 0 - 40 degrees: Sea Water 0.2 dB Rocky Ground 5 dB Average Gnd. 2 dB Frank Article: 223847 of rec.radio.amateur.antenna From: Roy Lewallen Subject: Re: "interesting" antenna design Date: Thu, 27 Apr 2006 12:13:46 -0700 Message-ID: <12525ve803tkr07@corp.supernews.com> References: <69488$4450c795$453d9423$12820@FUSE.NET> jawod wrote: > I was listening to 40M the other night and a reasonably clear SSB signal > came from a guy in Pennsylvania using 100 W to a rain gutter. > > It was apparently raining at the time in PA. > > All the mathematical modeling and tweaking discussed in this group ... > I thought the successful use of a rain gutter deserved some praise here. Why? There's nothing unusual or exceptional about it. I used one successfully on 80 meters for a number of years from an apartment in Denver. And when I was a kid my main 20 meter antenna was an approximately half wavelength of #28 enamled wire slammed in my window and running to a clothesline pole in the back yard. Insulator was a plastic curtain ring. Worked lots of stateside stations from Alaska with a homebrew 6L6 rig -- probably about 10 watts output. I've worked JA on 40 meter CW with a base loaded CB whip from a VW squareback and about 8 watts, and Alaska from Denver (good signal report on SSB) with 50 watts using a dipole strung around a basement. I worked New Hebrides on 40 meters with a bent attic dipole 16 feet above ground, (#28 hookup wire stapled to the eave) and running 1.5 watts. Solid copy, and I got a QSL. A rain gutter probably would have done better. Anyone who's been a ham for a few years probably has a handful of similar stories. What conclusions should we draw from them? Roy Lewallen, W7EL Article: 223848 of rec.radio.amateur.antenna From: Roy Lewallen Subject: Re: Velocity Factor and resonant frequency Date: Thu, 27 Apr 2006 12:26:35 -0700 Message-ID: <12526ndt5uges7a@corp.supernews.com> References: <124t6thopj1pea7@corp.supernews.com> <6547-444FA326-76@storefull-3255.bay.webtv.net> Richard Harrison wrote: > Roy, W7EL wrote: > "What is the velocity factor, and how did you calculate it?" > > Given: > length = 12 inches > diamwter = 6 in. > L = 38.6 microhenry > > I used formula (37) from Terman`s Handbook to calculate 25 turns in the > coil. 471 inches of wire are needed in the coil. > > The velocity of the EM wave traveling around the turns of the coil is > almost equal to the velocity in a straight wire. But, the time required > to travel 471 inches is 40 times the time required to travel 12 inches. > The velocity factor is the reciprocal of 40 or 0.025. Not quite what I was expecting, but let's see if I understand what it means. This means that if we put a current into one end of the inductor, it'll take about 40 ns for current to reach the other end, right? So we should expect a phase delay in the current of 180 degrees at 6.15 MHz, or about 30 degrees at 1 MHz, from one end to the other? Roy Lewallen, W7EL Article: 223849 of rec.radio.amateur.antenna From: John Ferrell Subject: Lightning suppressor? Message-ID: Date: Thu, 27 Apr 2006 19:54:13 GMT I have a Cushcraft A3S Beam on a tower. It does not currently have a lightning arrestor on the feed line and is working well. The feed arrangement is center conductor to one side of the driven element, shield to the other side. There is a coil of coax at the top as a choke. This leaves the elements and the coax ungrounded. I have relied entirely on disconnecting the antenna for protection. when not in use. I would like to put an arrestor in the line but recommendations are sketchy even from those who sell them. I assume it would be most effective at the base of the tower on the ground rod. The drawing in the ARRL Antenna Handbook shows the arrestor on a common station ground. Comments & opinions please... de W8CCW John John Ferrell W8CCW Article: 223850 of rec.radio.amateur.antenna From: "hasan schiers" Subject: Re: "interesting" antenna design Date: Thu, 27 Apr 2006 15:04:17 -0500 Message-ID: References: <69488$4450c795$453d9423$12820@FUSE.NET> <12525ve803tkr07@corp.supernews.com> Ionospherically reflected radio waves really do "want" to propagate, in spite of compromised antennas. About 40 years ago while running an old Knight Kit T-150 on 80 m cw, I had a few 100 mw of spur on 5.525 mhz. I got a QSL card from the FCC telling me that the Canadian's were not too happy with me, and could I please fix things. Rotten antenna, low power output, and I still got a QSL card. ...hasan, N0AN "Roy Lewallen" wrote in message news:12525ve803tkr07@corp.supernews.com... > Anyone who's been a ham for a few years probably has a handful of similar > stories. What conclusions should we draw from them? > > Roy Lewallen, W7EL Article: 223851 of rec.radio.amateur.antenna From: "Reg Edwards" References: <1250u68k0q1n13f@corp.supernews.com> <7JSdnf1lbv9TGc3ZRVny2Q@bt.com> <9tr152ph6d56om1mb1ffnrgh66a0vb86ru@4ax.com> Subject: Re: Multi hopping radio waves Date: Thu, 27 Apr 2006 21:21:18 +0100 Message-ID: Thank you Richard, and the others, for digging out and presenting the information from which I can deduce a ball-park figure. My original figure of 5 dB per hop for a ground reflection was slightly too high. It's nearer to 3.5 dB. I'm still thinking about it. But 4 dB is near enough. Not that it matters very much. I deduced 5 dB from my experience of signal strengths received from such places as the antipodes and the Western US states. It's not surprising hopping across just the North Atlantic results in zero dB loss. The excess path loss, over and above spreading loss, must be due to ground reflection losses. Just calculate backwards from received signal strength, path distance and the probable number of hops. It's easy to do this with dedicated computer programs. For very long distance paths assume that half the ground reflections are due to sea/ocean water and the other half is due to land masses and you won't go far wrong. Ground reflection losses at the transmitting and receiving sites can be ignored. Or such losses can be lumped together to constitute another complete hop. I needed the information to include in a simple program which predicts (approximately) path loss for multi-hop propagation. Program users cannot be expected to know incidence angles, ground conductivity and permittivity, Brewster angles etc, for every hop along a route. Some guesswork is needed on the part of the programmer to make a program useful. Despite your continuing abuse of the English language I know you are quite capable of understanding the foregoing waffle. I'm on South Eastern Australian Merlot tonight. Hic! I think the Chinese will be coming along shortly with their own high quality stuff. They are not just becoming adept with their high technology. Californian wine growers should look to their laurels. But no doubt you are all more immediately concerned with the price of oil, the gas in your tanks, and from where it may be obtained. Iraq and Iran for example. ---- Reg, G4FGQ Article: 223852 of rec.radio.amateur.antenna From: richardharrison@webtv.net (Richard Harrison) Subject: Re: Velocity Factor and resonant frequency Date: Thu, 27 Apr 2006 16:01:40 -0500 Message-ID: <17734-44513134-417@storefull-3251.bay.webtv.net> References: <12526ndt5uges7a@corp.supernews.com> Roy, W7EL wrote: "This means that if we put a current into one end of the inductor, it`ll take about 40 ns for current to reach the other end, right? So we should expect a phase delay in current of 180 degrees at 6.15 MHz, from one end to another?" Hopper`s rule is one foot traveled per nanosecond. 40 feet of wire takes 40 nanoseconds. The wavelength of 6.15 MHz is 48,8 or about 160 feet and in that space the phase rotates 360-degrees. 40 feet is 1/4 of 360-degrees or 90-degrees at 6.15 MHz. At 1 MHz, the wavelength is 300 meters. 12,2 meters of wire is about 15-degrees of delay by my $1-dollar Chinese calculator. Best regards, Richard Harrison, KB5WZI Article: 223853 of rec.radio.amateur.antenna From: Owen Duffy Subject: Re: "interesting" antenna design Message-ID: <3hd2525iugq7fnnabcpsqk32okj0ncklt7@4ax.com> References: <69488$4450c795$453d9423$12820@FUSE.NET> <12525ve803tkr07@corp.supernews.com> Date: Thu, 27 Apr 2006 21:35:16 GMT On Thu, 27 Apr 2006 12:13:46 -0700, Roy Lewallen wrote: >jawod wrote: >> I was listening to 40M the other night and a reasonably clear SSB signal >> came from a guy in Pennsylvania using 100 W to a rain gutter. >> >> It was apparently raining at the time in PA. >> >> All the mathematical modeling and tweaking discussed in this group ... >> I thought the successful use of a rain gutter deserved some praise here. > >Why? There's nothing unusual or exceptional about it. Indeed. Whilst it might have, and is probably still often done, it is unlikely to comply with limits on Maximum Permitted Exposure to EMR. It has a host of other disadvantages (EMC incompatibility, TVI/RFI, unreliable performance to name a few). The configuration is known as a CIA Special down here, being a covert antenna. I suppose it is commonly done in places where covenants prohibit external antennas. ... > >Anyone who's been a ham for a few years probably has a handful of >similar stories. What conclusions should we draw from them? Anything and everything "works" in the minds of amateurs. In the minds of some, a few QSOs is adequate proof that something "works", though I know you think differently Roy. Owen -- Article: 223854 of rec.radio.amateur.antenna From: Roy Lewallen Subject: Re: Velocity Factor and resonant frequency Date: Thu, 27 Apr 2006 14:33:31 -0700 Message-ID: <1252e5bg4o026fd@corp.supernews.com> References: <12526ndt5uges7a@corp.supernews.com> <17734-44513134-417@storefull-3251.bay.webtv.net> Sorry, my mistake. So let me rephrase my question: This means that if we put a current into one end of the inductor, it'll take about 40 ns for current to reach the other end, right? So we should expect a phase delay in the current of 90 degrees at 6.15 MHz, or about 15 degrees at 1 MHz, from one end to the other? Roy Lewallen, W7EL Richard Harrison wrote: > Roy, W7EL wrote: > "This means that if we put a current into one end of the inductor, it`ll > take about 40 ns for current to reach the other end, right? So we should > expect a phase delay in current of 180 degrees at 6.15 MHz, from one end > to another?" > > Hopper`s rule is one foot traveled per nanosecond. 40 feet of wire takes > 40 nanoseconds. > > The wavelength of 6.15 MHz is 48,8 or about 160 feet and in that space > the phase rotates 360-degrees. 40 feet is 1/4 of 360-degrees or > 90-degrees at 6.15 MHz. At 1 MHz, the wavelength is 300 meters. 12,2 > meters of wire is about 15-degrees of delay by my $1-dollar Chinese > calculator. > > Best regards, Richard Harrison, KB5WZI > Article: 223855 of rec.radio.amateur.antenna From: "N7QR" Subject: Smith Chart inventor Date: Thu, 27 Apr 2006 14:34:28 -0700 Message-ID: <445138e4$0$1007$39cecf19@news.twtelecom.net> Philip H. Smith, Fellow IEEE, was born 101 years ago this Saturday and died in 1987. Delevoped the Smith Chart for matching transmission lines (also developed the cloverleaf antenna.) Article: 223856 of rec.radio.amateur.antenna From: "jimmiefender@bellsouth.net" References: Subject: Re: J_Pole Trials and Tribulations Message-ID: Date: Thu, 27 Apr 2006 17:48:52 -0400 "jimbo" wrote in message news:cq2dnXJUtOYYCtPZnZ2dnUVZ_tednZ2d@comcast.com... >I have been trying to get an acceptable 2 meter antenna installed in my >attic. A J-Pole seemed to me the best solution for my attic space. You may >recall an earlier post where I discussed SWR on one of the ladder line >J-Poles I was working with. Well, I gave up on ladder line and constructed >a J-Pole from 1/2 inch copper tubing. I tuned it in my basement work shop >to give the best SWR and then took it up to the attic. The following table >shows the results. > > Basement Attic > > 144 1.90 1.80 > 145 1.65 2.00 > 146 1.50 2.10 > 147 1.60 2.25 > 147.995 1.90 2.25 > > Actually, probably not that bad for a first attempt at copper tubing. But, > I didn't like the fact that SWR was above 2.0 in my attic and that things > changed between my basement shop and the attic. I guess this design is > influenced by objects close by. > > So, somewhere in my surfing I came across the Arrow J-Pole. This is an end > fed, open stub commercial design that promises less that 1.5 SWR across > the band. Here are the results of my experiment with this antenna. > > Basement Attic > > 144 1.10 1.22 > 145 1.18 1.10 > 146 1.25 1.20 > 147 1.30 1.32 > 147.995 1.40 1.42 > > Not 1.0 SWR but certainly met the promise. And the best thing about this > design is that near by objects don't seem to have an impact on > performance. If I built one of these designs and tuned it in my basement > shop, it should give the same results in the attic. > > Anyway, just my subjective observations. > > jimbo - AJ7IM Article: 223857 of rec.radio.amateur.antenna From: "jimmiefender@bellsouth.net" References: Subject: Re: J_Pole Trials and Tribulations Message-ID: Date: Thu, 27 Apr 2006 17:54:26 -0400 "jimbo" wrote in message news:cq2dnXJUtOYYCtPZnZ2dnUVZ_tednZ2d@comcast.com... >I have been trying to get an acceptable 2 meter antenna installed in my >attic. A J-Pole seemed to me the best solution for my attic space. You may >recall an earlier post where I discussed SWR on one of the ladder line >J-Poles I was working with. Well, I gave up on ladder line and constructed >a J-Pole from 1/2 inch copper tubing. I tuned it in my basement work shop >to give the best SWR and then took it up to the attic. The following table >shows the results. > > Basement Attic > > 144 1.90 1.80 > 145 1.65 2.00 > 146 1.50 2.10 > 147 1.60 2.25 > 147.995 1.90 2.25 > > Actually, probably not that bad for a first attempt at copper tubing. But, > I didn't like the fact that SWR was above 2.0 in my attic and that things > changed between my basement shop and the attic. I guess this design is > influenced by objects close by. > > So, somewhere in my surfing I came across the Arrow J-Pole. This is an end > fed, open stub commercial design that promises less that 1.5 SWR across > the band. Here are the results of my experiment with this antenna. > > Basement Attic > > 144 1.10 1.22 > 145 1.18 1.10 > 146 1.25 1.20 > 147 1.30 1.32 > 147.995 1.40 1.42 > > Not 1.0 SWR but certainly met the promise. And the best thing about this > design is that near by objects don't seem to have an impact on > performance. If I built one of these designs and tuned it in my basement > shop, it should give the same results in the attic. > > Anyway, just my subjective observations. > > jimbo - AJ7IM You should be able to tweak the antenna on the bench until the SWR is more like 1.15:1 or so. Once you get it right there will probably be a lot less detuning once it is put in the attic Article: 223858 of rec.radio.amateur.antenna From: Roy Lewallen Subject: Re: "interesting" antenna design Date: Thu, 27 Apr 2006 15:13:47 -0700 Message-ID: <1252ggsfrdino25@corp.supernews.com> References: <69488$4450c795$453d9423$12820@FUSE.NET> <12525ve803tkr07@corp.supernews.com> <3hd2525iugq7fnnabcpsqk32okj0ncklt7@4ax.com> Owen Duffy wrote: > . . . > Anything and everything "works" in the minds of amateurs. In the minds > of some, a few QSOs is adequate proof that something "works", though I > know you think differently Roy. Not at all. Those whose performance criteria are limited to the binary categories of "works" and "doesn't work" are free to put the boundary between the two anywhere they want. It is rather entertaining, I have to admit, listening to two such people argue about antennas when the two have chosen very different boundaries. Roy Lewallen, W7EL Article: 223859 of rec.radio.amateur.antenna From: Owen Duffy Subject: Re: "interesting" antenna design Message-ID: <35h252lkle3veqrqpngv473hvilbch87sh@4ax.com> References: <69488$4450c795$453d9423$12820@FUSE.NET> <12525ve803tkr07@corp.supernews.com> <3hd2525iugq7fnnabcpsqk32okj0ncklt7@4ax.com> <1146175396.492716.292940@v46g2000cwv.googlegroups.com> <1146175906.621275.139890@i39g2000cwa.googlegroups.com> Date: Thu, 27 Apr 2006 22:30:53 GMT On 27 Apr 2006 15:11:46 -0700, "n3ox.dan@gmail.com" wrote: >Owen, > >Sorry I'm being a bit USA-centric. Maybe MPE limits in VK are more >strict? Dan, the greater issue here is the interpretation of of whether the radiator is accessible to members of the general public. If the kids next door come into the yard to retrieve their ball, it may be considered that it is accessible to the general public. Occupants of the premises (eg the rest of the family and visitors) may be considered to be the general public. Owen > >3.68 milliwatts per square centimeter here at 7MHz. > >I just noticed the "whilst" :-) > >-Dan -- Article: 223860 of rec.radio.amateur.antenna From: tclay@qmc.ph.msstate.edu Subject: Re: Lightning suppressor? Date: 27 Apr 2006 17:24:55 -0500 Message-ID: <87slnywtag.fsf@qmc.ph.msstate.edu> References: >I would like to put an arrestor in the line but recommendations are >sketchy even from those who sell them. I assume it would be most >effective at the base of the tower on the ground rod. The drawing in >the ARRL Antenna Handbook shows the arrestor on a common station >ground. Once you have more than one or two antennas, disconnecting the feedlines and throwing them out the window gets to be a real pain. you probably want to a) ground the shield of the coax at the base of the tower, and b) have a lightning arrestor where the coax enters the house or at your shack, and c) connect the grounds of the tower, shack, and power co. together I ground the coax shields at the base of my towers, run the coax underground to the house, and then have lightning arrestors at the house before the coax goes up to the shack on the 2nd story. Tor N4OGW Article: 223861 of rec.radio.amateur.antenna From: "stargatesg1" Subject: Plastic Antenna Insulators Message-ID: Date: Thu, 27 Apr 2006 22:39:22 GMT Anyone ever try using plastic drywall anchors for yagi antenna insulators? I'm wondering how they will hold up to UV and the weather in general. Thanks, RoD Article: 223862 of rec.radio.amateur.antenna From: "Jozef" References: <69488$4450c795$453d9423$12820@FUSE.NET> <12525ve803tkr07@corp.supernews.com> <3hd2525iugq7fnnabcpsqk32okj0ncklt7@4ax.com> <1252ggsfrdino25@corp.supernews.com> Subject: Re: "interesting" antenna design Date: Thu, 27 Apr 2006 19:00:19 -0400 Message-ID: <1146178776.858099@xwing.vermontel.net> My first winter in Vermont in 1985 had me wanting to get back on the air. So much snow and no antennas. Then I realized that my wood stove was sitting on brick hearth in the living room and the of the chimney outside above the roof was in the neighborhood of 32 - 33 feet. I feed the RF through coax to the foot of the wood stove and worked my fair share of DX. Beam went yp soon thereafter. "Roy Lewallen" wrote in message news:1252ggsfrdino25@corp.supernews.com... > Owen Duffy wrote: >> . . . >> Anything and everything "works" in the minds of amateurs. In the minds >> of some, a few QSOs is adequate proof that something "works", though I >> know you think differently Roy. > > Not at all. Those whose performance criteria are limited to the binary > categories of "works" and "doesn't work" are free to put the boundary > between the two anywhere they want. It is rather entertaining, I have to > admit, listening to two such people argue about antennas when the two have > chosen very different boundaries. > > Roy Lewallen, W7EL Article: 223863 of rec.radio.amateur.antenna From: Tony Roma Subject: Re: I blame the ARRL for all the homosexual posts. Please Read. Message-ID: References: <22se42d1ndkmbrj99p6675l6k2t16rplk4@4ax.com> Date: Fri, 28 Apr 2006 02:01:08 GMT >On Wed, 19 Apr 2006 20:54:39 GMT, Skirt Chaser >wrote: > >> >>I know you're all going to disagree >>with me, but a man touching and sucking on another man's cock and fucking >>his ass just ain't right. > You said a mouthful. Oh and I agree with you. It just aint natural! I mean imagine a guy sucking on my cock. what am I supposed to do, come in his mouth??? Very disturbing! Article: 223864 of rec.radio.amateur.antenna From: "Frank's" References: Subject: Re: Multi hopping radio waves Message-ID: Date: Fri, 28 Apr 2006 02:21:28 GMT "Reg Edwards" wrote in message news:CpqdnRLuOcmmr8zZRVnyvw@bt.com... > Frank wrote - >> Some approximate examples at 7 MHz with angles of incidence >> from 0 - 40 degrees: >> >> Sea Water 0.2 dB >> Rocky Ground 5 dB >> Average Gnd. 2 dB > ========================================= > Thanks Frank, > > Your figures for 7 MHz are representative of HF. > > Nobody is particularly interested in MF, LF or VLF. > > They confirm my latest estimate of an average, between sea water and > dry land, of roughly 3.5 dB per ground reflection. > ---- > Reg. No problem Reg. I did the computations recently trying to estimate the path loss, on 7 MHz, >from the west coast to Europe via the long path. The various ground losses >from all kinds of ground, including polar ice, and fresh water, are all fairly low. The real problem was to estimate the losses due to the incidence with the diffuse, conductive, ionospheric plasmas, and also to consider the possibility that some inonospheric ducting occurs. So far I have not attempted to estimate these losses, but they must be very high, since only considering ground incidence produces unrealistically low path losses. Frank Article: 223865 of rec.radio.amateur.antenna Date: Thu, 27 Apr 2006 21:33:20 -0500 From: Tom Ring Subject: Re: Missing Degrees in Mobile Antennas? References: <9vp252pqm2fues06g4bq2kq0r0s6mt1ed3@4ax.com> Message-ID: <44517ef1$0$1004$39cecf19@news.twtelecom.net> Richard Clark wrote: > On Thu, 27 Apr 2006 20:28:12 GMT, "Cecil Moore" > wrote: > >>There seems to be an assumption by some posters here that >>a mobile antenna must be electrically 90 degrees in length. > > "Some?" In fact, only one and he cites you (which is notable in its > irony for many reasons) as his authority on this subject. Why don't > you simply email him your contribution? Hang on, that was Cecil that said that!?!? Mister "a coil fills in the missing degrees on the stinger"? tom K0TAR Article: 223866 of rec.radio.amateur.antenna Date: Thu, 27 Apr 2006 21:37:14 -0500 From: Tom Ring Subject: Re: Missing Degrees in Mobile Antennas? References: <9vp252pqm2fues06g4bq2kq0r0s6mt1ed3@4ax.com> Message-ID: <44517fdb$0$1010$39cecf19@news.twtelecom.net> Richard Clark wrote: > On Thu, 27 Apr 2006 20:28:12 GMT, "Cecil Moore" > wrote: > >>There seems to be an assumption by some posters here that >>a mobile antenna must be electrically 90 degrees in length. > > "Some?" In fact, only one and he cites you (which is notable in its > irony for many reasons) as his authority on this subject. Why don't > you simply email him your contribution? Or, to put it more "accurately", from Cecil's perspective, it fills in the missing degrees at the position the coil sits. tom K0TAR Article: 223867 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Missing Degrees in Mobile Antennas? References: <9vp252pqm2fues06g4bq2kq0r0s6mt1ed3@4ax.com> <44517fdb$0$1010$39cecf19@news.twtelecom.net> Message-ID: Date: Fri, 28 Apr 2006 02:50:56 GMT Tom Ring wrote: > Or, to put it more "accurately", from Cecil's perspective, it fills in > the missing degrees at the position the coil sits. No, in the case of a base-loaded antenna, the "missing" degrees are filled in at the impedance discontinuity *between* the coil and the stinger. -- 73, Cecil http://www.qsl.net/w5dxp Article: 223868 of rec.radio.amateur.antenna Date: Thu, 27 Apr 2006 21:58:07 -0500 From: Tom Ring Subject: Re: Missing Degrees in Mobile Antennas? References: <9vp252pqm2fues06g4bq2kq0r0s6mt1ed3@4ax.com> <44517fdb$0$1010$39cecf19@news.twtelecom.net> Message-ID: <445184bf$0$1018$39cecf19@news.twtelecom.net> Cecil Moore wrote: > Tom Ring wrote: > >> Or, to put it more "accurately", from Cecil's perspective, it fills in >> the missing degrees at the position the coil sits. > > > No, in the case of a base-loaded antenna, the "missing" > degrees are filled in at the impedance discontinuity > *between* the coil and the stinger. And that differs from your bugcatcher how? tom K0TAR Article: 223869 of rec.radio.amateur.antenna From: biascomms Subject: Re: Plastic Antenna Insulators References: Message-ID: Date: Fri, 28 Apr 2006 05:54:38 GMT stargatesg1 wrote: > Anyone ever try using plastic drywall anchors for yagi antenna insulators? > I'm wondering how they will hold up to UV and the weather in general. It depends on the plastic material - it's worth doing the microwave oven test before using it. I find that PVC that's OK in the microwave oven usually stands up to UV well. Bob -- Everything gets easier with practice, except getting up in the morning! Article: 223870 of rec.radio.amateur.antenna From: "Jeff" Subject: Re: Smith Chart inventor Date: Fri, 28 Apr 2006 08:30:37 +0100 Message-ID: References: <445138e4$0$1007$39cecf19@news.twtelecom.net> > Smith did not invent the Smith Chart. He simplified, for HF use only, > charts which had been in existence since the Victorian Age, which > covered all transmission line frequenies down to telephone and power > frequencies. > That is not quite correct, what Smith did was to take to concept of the pre-existing equations and a rectangular chart which covered a limited range of impedances and develop them into a circular, more complex chart, that covered a full range of impedances. See the Introduction to Smith's book "Electronic Applications of the Smith Chart". Regards Jeff Article: 223871 of rec.radio.amateur.antenna From: Roy Lewallen Subject: Re: Plastic Antenna Insulators Date: Fri, 28 Apr 2006 00:54:54 -0700 Message-ID: <1253iiep6f1hn5f@corp.supernews.com> References: biascomms wrote: > > It depends on the plastic material - it's worth doing the microwave oven > test before using it. I find that PVC that's OK in the microwave oven > usually stands up to UV well. That's interesting. I believe carbon is sometimes added to plastics to improve UV resistance, and it would surely increase the loss at microwave frequencies. And many plastics like clear polyethylene are excellent low loss materials and won't heat in a microwave oven, but deteriorate rapidly in sunlight. Are you sure the correlation between microwave results and UV resistance isn't just a coincidence of the materials you happen to have tested -- sort of like having an accident just after a black cat crosses your path? Roy Lewallen, W7EL Article: 223872 of rec.radio.amateur.antenna From: "Yuri Blanarovich" References: <9vp252pqm2fues06g4bq2kq0r0s6mt1ed3@4ax.com> <44517ef1$0$1004$39cecf19@news.twtelecom.net> Subject: Re: Missing Degrees in Mobile Antennas? Message-ID: Date: Fri, 28 Apr 2006 09:21:57 -0400 >>>There seems to be an assumption by some posters here that >>>a mobile antenna must be electrically 90 degrees in length. >> Must be? Must is only death and taxes! Resonant monopole must be 90 electrical degrees and resonant dipole must be 180 electrical degrees long. But that "must" does not apply to antennas as chosen by users. You can use light bulb, screwdriver, bedsprings, wet noodle or any piece of RF conducting material of any length, shape you like, just question how good of antenna it is. We used 90 deg. monopole in discussion to show typical loaded or mobile antenna in order to avoid detours to la-la land (cases when current can be and is equal) and to stay on the subject of current magnitude along the typical loading coil. 73 Yuri, K3BU Article: 223873 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Missing Degrees in Mobile Antennas? References: <9vp252pqm2fues06g4bq2kq0r0s6mt1ed3@4ax.com> <44517ef1$0$1004$39cecf19@news.twtelecom.net> Message-ID: Date: Fri, 28 Apr 2006 13:36:13 GMT Yuri Blanarovich wrote: > We used 90 deg. monopole in discussion to show typical loaded or mobile > antenna in order to avoid detours to la-la land (cases when current can be > and is equal) and to stay on the subject of current magnitude along the > typical loading coil. Take a look at the rest of the posting, Yuri. I show where a 1/4WL stub can be made up of 30 degrees of 450 ohm line plus 11 degrees of 50 ohm line. The impedance discontinuity (at a point) furnishes the "missing" 49 degrees of stub. At 4 MHz, that would make a 1/4WL stub only 23.4 ft long or about 10% of a wavelength instead of 25%. Has anything been published on using multiple Z0's to shorten the physical length of a stub? -- 73, Cecil http://www.qsl.net/w5dxp Article: 223874 of rec.radio.amateur.antenna From: Buck Subject: TT-247 and 102 whip for mobile antenna ? Message-ID: <6na4521tmlo4ipifhhgo0u5dvt43t3l25c@4ax.com> Date: Fri, 28 Apr 2006 10:53:33 -0400 I have a TenTec 247 manual antenna tuner. I am thinking about installing a roof-mount over the space between the driver and passenger in the front of my mini-van and hanging my TT tuner below it. I understand the combination with automatic tuners works well, but I have been warned against using the TT to tune short antennas on low frequencies. Of course, this was in reference to dipoles and base antennas. The problem is reportedly that the loading coil will heat up and be damaged and have to be re-wound. I have about a 2 foot extension that I may also use to extend the antenna a little. I don't have the money to spend on auto-tuners and I have everything but the whip and mount for the antenna configuration I just described. comments? -- 73 for now Buck N4PGW Article: 223875 of rec.radio.amateur.antenna From: "Steve N." Subject: Re: Smith Chart inventor Date: Fri, 28 Apr 2006 10:13:50 -0500 Message-ID: References: <445138e4$0$1007$39cecf19@news.twtelecom.net> "Reg Edwards" wrote in message news:z_6dnXgHUIxG3szZnZ2dnUVZ8qCdnZ2d@bt.com... > ... > You should be warned against using Smith Charts at frequencies less > than about 1.5 or 2 MHz. Errors can be introduced of which you may be > unaware.... ---- Reg. I'm curious. Would you briefly summarize the type/cause of the Medium Frequency errors. 73, Steve, K9DCI Article: 223876 of rec.radio.amateur.antenna From: richardharrison@webtv.net (Richard Harrison) Subject: Re: Velocity Factor and resonant frequency Date: Fri, 28 Apr 2006 10:12:30 -0500 Message-ID: <8655-445230DE-371@storefull-3253.bay.webtv.net> References: Cecil, W5DXP wrote: "Dr. Corum`s VF equation predicts a VF of approximately double Richard`s----." I wonder why? Dr. Terman wrote that the wave follows the turns in a coil. My recollection of common solid-dielectric coax VF is about 2/3 that of free-space due to the fense plastic. Twice the velocity factor in a coil requires a wave traveling faster than light or taking a short-cut around the turns. I often learn from my mistakes. Where did I err? Best regards, Richard Harrison, KB5WZI Article: 223877 of rec.radio.amateur.antenna From: "Tom Donaly" Subject: Re: Missing Degrees in Mobile Antennas? References: <9vp252pqm2fues06g4bq2kq0r0s6mt1ed3@4ax.com> <44517fdb$0$1010$39cecf19@news.twtelecom.net> <445184bf$0$1018$39cecf19@news.twtelecom.net> <1146236524.933305.75290@j33g2000cwa.googlegroups.com> Message-ID: <8%q4g.70661$H71.41842@newssvr13.news.prodigy.com> Date: Fri, 28 Apr 2006 16:01:08 GMT w8ji@akorn.net wrote: > Poor Yuri. > > Hanging his hat on Cecil, but now Cecil is getting the picture and > yanking the rug out from under Yuri and his "missing electrical degree > cutrrent taper and phase shift theory". > > It only took three or four years, but at least that's better than > Fractenna. :-) > > Cecil Moore wrote: > >>The whole point is that it doesn't differ. >>That's how my bugcatcher works. >> >>Here are the three parts to the answer. >> >>1. The base-loading coil furnishes a delay equal to >>a certain number of degrees which is nowhere near zero >>degrees. Half of a coil self-resonant at 4 MHz would >>provide 45 degrees of shift. >> >>2. Using EZNEC to add a stinger to resonate the antenna >>on 4 MHz, I find that's 11.5 degrees of straight element. >>45 degrees plus 11.5 degrees is 56.5 degrees. >> >>3. 90 - 56.5 = 33.5 degrees which is the "missing" >>degrees filled in by the impedance discontinuity. >>We can even estimate the ratio of the Z0 of the coil >>to the Z0 of the stinger to be 5.0. >>-- >>73, Cecil http://www.qsl.net/w5dxp > > Yes, except that Cecil is just replacing one idiotic theory with another. That's o.k., he has to do something out there in the Texas hinterlands to keep out of trouble. The unfortunate thing, though, is that there might be someone in this world who takes him seriously. 73, Tom Donaly, KA6RUH Article: 223878 of rec.radio.amateur.antenna From: "Steve N." Subject: Re: Missing Degrees in Mobile Antennas? Date: Fri, 28 Apr 2006 11:08:53 -0500 Message-ID: References: <9vp252pqm2fues06g4bq2kq0r0s6mt1ed3@4ax.com> <44517fdb$0$1010$39cecf19@news.twtelecom.net> <445184bf$0$1018$39cecf19@news.twtelecom.net> "Cecil Moore" wrote in message news:qCn4g.77204$dW3.54012@newssvr21.news.prodigy.com... > Tom Ring wrote: > > Cecil Moore wrote: > >> There seems to be an assumption by some posters here that a mobile antenna must be electrically 90 degrees in length. Here's a simple transmission line example to illustrate why that is not true in the case of a loading coil used with straight sections of antenna. In the following example, all transmission lines are lossless. ... 73, Cecil http://www.qsl.net/w5dxp You guys sure like to go on-and-on starting with someones "rule of thumb" or catch phrase, taking either correct or not so correct math to prove or disprove what you may or may not already know...or just wave your flag in otheres faces. I guess my real point is that I see many uses of "electrical length" and "physical length" many of which are not used correctly. If the mental model(s) we have and are trying to use as a basis for a field of study don't quite work well enough to be useful most all the time, then they probably aren't correct. The best model is one that always applies when applied appropriately and you won't know what appropriate means unless you have a good model to base it on. I know this soulds like circular reasonong, but that's the way it works and the best way I can descxribe it. I think "electrical length of a conbination of components" is a poor way to look at it and therefore a poor mental model to use. Bring in an uneeded term called "electrical length" or looking for the "missing degrees" is pretty much a red herring complication. I maintain that trying to fit an "electricall length" to such a combination helps none in the understanding. You do the math, get the correct answer and you are done. You don't need an extra "name". My point would be that "elecreical length" is only correctly applicable to _A_ single length of Transmisison line. trying to force it into every other situation is only causing confusion and I should rest my case here, but.... We need it because there is a velocity factor and therefore, the phisical length is no longer good enough for discussion. It is obvious that hooking up different lengths of different characteristic impedance transmisison line has a complex effect on what you wind up with and it is therefore inapropriate to use that specific terminology to describe the complex situation. I didn't check Cecil's math, but assuming he did it correctly, this is no surprise - it is expected as a result. However, have a need to ascribe a TOTAL "electrical length" based on individual "electrical lengths" of a complex combination of lines is inappropriate - not helpful for real nunderstanding. You might be inclined, and therefore properly understood, if you talk about the finished product in a slightly different mannor. If the phase angle and impedance is the same as you would have gotten with some (single hunk of) reference line, then you could say that it "appears equivalent to" a such-and-such line with an electrical length of X degrees, but the complex combinatin no longer has something we can rightly call an electrical length because it is not an _it_, but a _them_...if you get my drift. You guys are going to use up all the words for the rest of us... (:-) 73, Steve, K9DCI asbestos shorts fresh out of the wash... Article: 223879 of rec.radio.amateur.antenna From: "Cecil Moore" References: <9vp252pqm2fues06g4bq2kq0r0s6mt1ed3@4ax.com> <44517fdb$0$1010$39cecf19@news.twtelecom.net> <445184bf$0$1018$39cecf19@news.twtelecom.net> <1146236524.933305.75290@j33g2000cwa.googlegroups.com> Subject: Re: Missing Degrees in Mobile Antennas? Message-ID: Date: Fri, 28 Apr 2006 16:30:28 GMT wrote: > Hanging his hat on Cecil, but now Cecil is getting the picture and > yanking the rug out from under Yuri and his "missing electrical degree > cutrrent taper and phase shift theory". Is the purpose of this newsgroup to smear individuals or to get to the technical facts? Nobody is 100% correct 100% of the time. The coil still occupies tens of degrees and still suffers a current taper because of that delay. > It only took three or four years, but at least that's better than > Fractenna. :-) I wouldn't laugh just yet, Tom. There's plenty of misconceptions on both sides. The delay through the loading coil is still tens of degrees, not anywhere close to the near-zero degrees that you have been asserting for years. The delay through a typical 75m bugcatcher coil appears to be about ~35 degrees with ~11 degrees of stinger. The "missing" ~44 degrees occurs at the impedance discontinuity between the coil and the stinger just as it does in my 450/50 ohm stub example. The 3 nS delay measured by you and the undetectable delay measured by W7EL were invalid measurements of delay. Standing wave current suffers zero delay all along a 1/2WL dipole whether it be in a wire or in a coil. The delay through a typical mobile loading coil on 4 MHz appears to be about 25 nS about half of what one would get in a straight wire equal to the wire used in the coil. -- 73, Cecil, W5DXP Article: 223880 of rec.radio.amateur.antenna From: Pierre Desjardins Subject: Wire diameter vs Impedance Message-ID: Date: Fri, 28 Apr 2006 12:31:42 -0400 Hi to all.. It is well know that a reduction in the diameter of the wire must be compensated by a higher antenna length to maintain resonance. I am looking for an explanation of the reason for this. Why the total reactance becomes more capacitive? I know math formula showing the variation of the inductance of the wire vs its diameter, but I a looking for the real reason, not the mathematical consequence. I suspect that a higher diam cause higher transormation of AC to electromagnetic energy on a segment delta(l) so that a shorter physical length would be needed to include the full electrical 180 degrees of a dipole.. but not really sure of this. Any comment would be welcome Thanks, and 73 de Pierre ve2pid Article: 223881 of rec.radio.amateur.antenna From: "Cecil Moore" References: <8655-445230DE-371@storefull-3253.bay.webtv.net> Subject: Re: Velocity Factor and resonant frequency Message-ID: Date: Fri, 28 Apr 2006 16:47:21 GMT "Richard Harrison" wrote: > Twice the velocity factor in a coil requires a wave traveling faster > than light or taking a short-cut around the turns. > > I often learn from my mistakes. Where did I err? The current does take a short-cut due to adjacent coil coupling. But please note the velocity factor only approximately doubles >from the "round and round the coil" calculation. Even though a VF of 0.04 is ~double the "round and round the coil" approximation, it is still 96% away from the VF=1.0 originally asserted by W8JI which assumes that all the coils couple 100% to all the other coils. -- 73, Cecil, W5DXP Article: 223882 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Missing Degrees in Mobile Antennas? References: <9vp252pqm2fues06g4bq2kq0r0s6mt1ed3@4ax.com> <44517fdb$0$1010$39cecf19@news.twtelecom.net> <445184bf$0$1018$39cecf19@news.twtelecom.net> Message-ID: Date: Fri, 28 Apr 2006 18:04:29 GMT Steve N. wrote: > You might be inclined, and therefore properly understood, if you talk > about the finished product in a slightly different mannor. If the phase > angle and impedance is the same as you would have gotten with some (single > hunk of) reference line, then you could say that it "appears equivalent to" > a such-and-such line with an electrical length of X degrees, but the complex > combinatin no longer has something we can rightly call an electrical length > because it is not an _it_, but a _them_...if you get my drift. Steve, I put "missing" in quotes because there is no missing part of the antenna. I've been saying for months that a 75m mobile antenna doesn't have to be 90 degrees long to be resonant. All that is required is that (Vfor+Vref) be in phase with (Ifor+Iref) where those are phasor additions. The real world phase shift accomplished by an impedance discontinuity is caused by instantaneous interference and doesn't require a delay. The basics of such an event are covered in my '05 magazine article available at http://www.qsl.net/w5dxp/energy.htm -- 73, Cecil http://www.qsl.net/w5dxp Article: 223883 of rec.radio.amateur.antenna From: richardharrison@webtv.net (Richard Harrison) Subject: Re: Velocity Factor and resonant frequency Date: Fri, 28 Apr 2006 14:03:53 -0500 Message-ID: <6547-44526719-471@storefull-3255.bay.webtv.net> References: Cecil, W5DXP wrote: "The current does take a short-cut due to adjacent coil coupling." R.W.P. King wrote on page 81 of Transmission Lines, Antennas, and Wave Guides: "The electromagnetic field in the near zone is characterized by an inverse-square law for amplitude and by quasi-instantaneous action." I still don`t know what to make of King`s assertion regards instantaneous action. Best regards, Richard Harrison, KB5WZI Article: 223884 of rec.radio.amateur.antenna From: "Yuri Blanarovich" References: <9vp252pqm2fues06g4bq2kq0r0s6mt1ed3@4ax.com> <44517fdb$0$1010$39cecf19@news.twtelecom.net> <445184bf$0$1018$39cecf19@news.twtelecom.net> <1146236524.933305.75290@j33g2000cwa.googlegroups.com> Subject: Re: Missing Degrees in Mobile Antennas? Message-ID: Date: Fri, 28 Apr 2006 15:30:24 -0400 wrote in message news:1146236524.933305.75290@j33g2000cwa.googlegroups.com... > Poor Yuri. > > Hanging his hat on Cecil, but now Cecil is getting the picture and > yanking the rug out from under Yuri and his "missing electrical degree > cutrrent taper and phase shift theory". > > It only took three or four years, but at least that's better than > Fractenna. :-) > "Brilliant" Tom! putting words in my mouth, twisting and trying to weasel out of technical arguments by spewing personal crapattack. Argument is about you claiming current in a loading coil is ALWAYS the same, which has been shown to be WRONG and crap on your web site is still proof of it. You can make up stories about my theories, it will not prove you RIGHT. Where did you get your "engineering" degree Tom and by what rights you use "JI Engineering"? That smells with fraud!!! Care to continue with bulshit? Grove up or get help! 73 Yuri Article: 223885 of rec.radio.amateur.antenna Subject: Re: blame the posters not arrl From: Ray Norshine References: <22se42d1ndkmbrj99p6675l6k2t16rplk4@4ax.com> <1146238178.410103.29330@y43g2000cwc.googlegroups.com> Message-ID: Date: Fri, 28 Apr 2006 19:30:47 GMT "an old freind" wrote in news:1146238178.410103.29330@y43g2000cwc.googlegroups.com: > > Tony Roma wrote: >> >On Wed, 19 Apr 2006 20:54:39 GMT, Skirt Chaser >> >wrote: > >> You said a mouthful. Oh and I agree with you. It just aint natural! > > funny it occours outside of man and outside the primates in nature all > the time > an old freid kb9rqz@hotmail.com an old freind kb9rqz@amsat.org an old freind kb9rqz_ars@hotmail.com an old freind kb9rqz_ars@yahoo.com an old freind upperpenarmyguy@yahoo.com an old friend kb9rqz@amsat.org an old friend kb9rqz@hotmail.com an old friend kb9rqz@yahoo.com an_old_friend konstans@hotmail.com "gte help" Article: 223886 of rec.radio.amateur.antenna From: "Yuri Blanarovich" References: Subject: Re: Wire diameter vs Impedance Message-ID: Date: Fri, 28 Apr 2006 15:36:51 -0400 Try increased capacitance from larger wire diameter, larger surface (plate) area. Capacitance goes up, inductance (length) has to come down in order to maintain resonance - LC circuit in standing wave environment. 73 Yuri, K3BU, VE3BMV, VE1BY "Pierre Desjardins" wrote in message news:icg45291fio7hru744scc2jjioa5ik20m8@4ax.com... > Hi to all.. It is well know that a reduction in the diameter of the > wire must be compensated by a higher antenna length to maintain > resonance. > > I am looking for an explanation of the reason for this. Why the total > reactance becomes more capacitive? I know math formula showing the > variation of the inductance of the wire vs its diameter, but I a > looking for the real reason, not the mathematical consequence. > > I suspect that a higher diam cause higher transormation of AC to > electromagnetic energy on a segment delta(l) so that a shorter > physical length would be needed to include the full electrical 180 > degrees of a dipole.. but not really sure of this. > > Any comment would be welcome > > Thanks, and 73 de Pierre ve2pid Article: 223887 of rec.radio.amateur.antenna From: "Steve N." Subject: Re: Missing Degrees in Mobile Antennas? Date: Fri, 28 Apr 2006 17:11:21 -0500 Message-ID: References: <9vp252pqm2fues06g4bq2kq0r0s6mt1ed3@4ax.com> <44517fdb$0$1010$39cecf19@news.twtelecom.net> <445184bf$0$1018$39cecf19@news.twtelecom.net> "Cecil Moore" wrote in message news:NOs4g.21565$tN3.16461@newssvr27.news.prodigy.net... > Steve N. wrote: > > ...if you get my drift. > > Steve, I put "missing" in quotes because there is no missing part of > the antenna. I think I understand your intent. What I say is drop the following sentence: "I've been saying for months that a 75m mobile antenna doesn't have to be 90 degrees long to be resonant. Forget electrical length discussions in regard to anything but a single transmission line piece. I don't think it makes any improvement in understanding what is going on to add talk about something you want to call the electrical length of a complex system of lines and components. I think it adds unnecessary complication. My opinion is that this is taking a concept used in transmission line discussions and applying it where it is not needed. Though I didn't verify your math on the original example, I don't find the type of result surprising and doing he math is all that is needed. I would not have expected that the "degrees" of electrical length to add up to 90, or whatever an equivalent antenna or t-line length would have been. I do understand the desire to form what I call a "mental model" which allows us to understand how things work so that we can use them. Lord knows that waves need some kind of help to get them into our minds so we can feel comfortable about how this all fits together. In fact, sometimes I get the impression these discussions become a battle between two mental models that may work for the individual posters, but don't fit into the other's model and many words ensue trying to pull each other over to the other's mental model paradigm. Talk such as the following it sufficient. (although I'd have to think about the specific thing you say here since I don't think about transmission line things in those terms) > All that is > required is that (Vfor+Vref) be in phase with (Ifor+Iref) where > those are phasor additions. ...detail snipped > -- 73, Cecil http://www.qsl.net/w5dxp Whatever lights your fire. It is fun reading some of the discussions, though 73, Steve, K9DCI Article: 223888 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Velocity Factor and resonant frequency References: <6547-44526719-471@storefull-3255.bay.webtv.net> Message-ID: Date: Fri, 28 Apr 2006 22:39:08 GMT Richard Harrison wrote: > Cecil, W5DXP wrote: > "The current does take a short-cut due to adjacent coil coupling." > > R.W.P. King wrote on page 81 of Transmission Lines, Antennas, and Wave > Guides: > "The electromagnetic field in the near zone is characterized by an > inverse-square law for amplitude and by quasi-instantaneous action." > > I still don`t know what to make of King`s assertion regards > instantaneous action. From the IEEE Dictionary: "instantaneous - A qualifying term indicating that no delay is purposely introduced in the action of the device." Does anyone have a formula for the coupling factor between turns in a coil? -- 73, Cecil http://www.qsl.net/w5dxp Article: 223889 of rec.radio.amateur.antenna From: "stargatesg1" References: Subject: Re: Plastic Antenna Insulators Message-ID: <8mx4g.61$3l4.24@trnddc03> Date: Fri, 28 Apr 2006 23:15:16 GMT Thanks to all for the replies. I am considering building a few VHF and UHF yagi's for weak signal work and just kicking ideas around in my head. I was at Lowe's hardware the other day and spied the plastic drywall anchors. I took one from the package and over to the steel and aluminum rod isle and to my surprise one size of anchor was a PERFECT fit to 3/16" rod and another to 1/8". The 1/8" (rod size) anchor even looks like the clamping ears (for lack of a better description) would extend and lock the anchor into place in a 1/16" or 3/32" antenna boom. If they can stand the rigors of the weather and have no detrimental effect at the frequencies being used, they look almost ideal! I don't remember the color of the material but different sizes are different colors. It might be interesting to throw a few in the microwave to see if they have any reactivity at even that high of a frequency. If they pass that test, I think I will build a yagi and see how long it last's. At worst, all I would have to do is replace them with Delrin in a year or two. I was hoping someone on here had tried it already but guess I get to be the guinea pig:-) I will post later how it comes out. Thanks, RoD "Highland Ham" wrote in message news:m9WdnYmih-XtaMzZRVnyrQ@pipex.net... > biascomms wrote: > > stargatesg1 wrote: > > > >> Anyone ever try using plastic drywall anchors for yagi antenna insulators? > >> I'm wondering how they will hold up to UV and the weather in general. > > > > It depends on the plastic material - it's worth doing the microwave oven > > test before using it. I find that PVC that's OK in the microwave oven > > usually stands up to UV well. > =========================== > To be UV resistant the plastic should be black ,eg it contains carbon > black ( like soot) If ,in general, plastic material is exposed to sun > light it deteriorates over time (especially when pigments are involved). > Example: coloured polypropylene rope . > If that material would be black ,it would have a very long life. > But then the sales of this material would decline ;)), hence you only > find coloured polypropylene rope ,blue ,orange ,red , yellow ,etc ,at > least in the UK. > > Here in the north of Scotland (no sun in abundance) I use > (blue)polypropylene guys on a 13m (40ft)mast ,which have to be replaced > every 7 -8 years .But it is cheap. > Polyester rope as used on sailing boats is UV resistant (even without > carbon black) and would last 30+ years ,but it is relatively expensive. > > Plastic antenna insulators (sold in the UK ) are usually black , so are > the outdoor balun enclosures and plastic insulators on Yagi antennes. > > In the 1960-70s when industrial instrumentation and control equipment > was predominantly pneumatic , coloured (polyethylene) tubing was often > used to identify types of signals in (indoor) control rooms . But since > lighting was often by fluorescent tubes , their UV radiation caused the > tubing to deteriorate and crack. > When it became a common problem an American company Samuel Moore then > produced black tubing with coloured stripes, solving the UV triggered > problem. > > Frank GM0CSZ / KN6WH > Article: 223890 of rec.radio.amateur.antenna From: Fred Subject: Re: blame the posters not arrl Message-ID: References: <22se42d1ndkmbrj99p6675l6k2t16rplk4@4ax.com> <1146238178.410103.29330@y43g2000cwc.googlegroups.com> Date: Sat, 29 Apr 2006 00:29:40 GMT On 28 Apr 2006 08:29:38 -0700, "an old freind" wrote: > >Tony Roma wrote: >> >On Wed, 19 Apr 2006 20:54:39 GMT, Skirt Chaser >> >wrote: > >> You said a mouthful. Oh and I agree with you. It just aint natural! >funny it occours outside of man and outside the primates in nature all >the time So you are as stupid as a monkey or a dog? Article: 223891 of rec.radio.amateur.antenna From: Bob Subject: Re: TT-247 and 102 whip for mobile antenna ? References: <6na4521tmlo4ipifhhgo0u5dvt43t3l25c@4ax.com> Message-ID: Date: Sat, 29 Apr 2006 02:06:48 GMT Not counting the potential tuner problems you mention, my experience is a 102” whip with no loading will work ok on 10-20m, but on 40m and below it sucks. Bob Buck wrote: > I have a TenTec 247 manual antenna tuner. I am thinking about > installing a roof-mount over the space between the driver and > passenger in the front of my mini-van and hanging my TT tuner below > it. I understand the combination with automatic tuners works well, > but I have been warned against using the TT to tune short antennas on > low frequencies. Of course, this was in reference to dipoles and base > antennas. The problem is reportedly that the loading coil will heat > up and be damaged and have to be re-wound. > > I have about a 2 foot extension that I may also use to extend the > antenna a little. > > I don't have the money to spend on auto-tuners and I have everything > but the whip and mount for the antenna configuration I just described. > > comments? > > Article: 223892 of rec.radio.amateur.antenna From: "Dr.Death" Subject: Re: blame the posters not arrl Date: Fri, 28 Apr 2006 21:24:17 -0500 Message-ID: <1255jifnpo0fnb2@corp.supernews.com> References: <22se42d1ndkmbrj99p6675l6k2t16rplk4@4ax.com> <1146238178.410103.29330@y43g2000cwc.googlegroups.com> "Fred" wrote in message news:cqc5525d7mu7ahh5nv0q89grsi151lcqr3@4ax.com... > On 28 Apr 2006 08:29:38 -0700, "an old freind" > wrote: > >> >>Tony Roma wrote: >>> >On Wed, 19 Apr 2006 20:54:39 GMT, Skirt Chaser >>> >wrote: >> >>> You said a mouthful. Oh and I agree with you. It just aint natural! >>funny it occours outside of man and outside the primates in nature all >>the time > > So you are as stupid as a monkey or a dog? Give the monkey and the dog some credit, they are WAY more intelligent than Markie-tard Article: 223893 of rec.radio.amateur.antenna From: Buck Subject: Re: TT-247 and 102 whip for mobile antenna ? Message-ID: References: <6na4521tmlo4ipifhhgo0u5dvt43t3l25c@4ax.com> <1146238198.871231.23670@e56g2000cwe.googlegroups.com> Date: Fri, 28 Apr 2006 22:46:07 -0400 On 28 Apr 2006 08:29:58 -0700, "n3ox.dan@gmail.com" wrote: >If there is a heating problem with a short dipole, there will be a >heating problem with a 102" whip. > >Some automatic tuners may do OK with the short whip. I think SGC does >this, but if it works and is reasonably low-loss it is because the >tuner is designed to do well with a short whip. > >One way to make the tuner match a short whip better on low frequencies >is to include a loading coil, in this case, at the base, to bring the >antenna into resonance. The impedance of the antenna will then be a low >resistive impedance, rather than a low resistive part and lots of >capacitative reactance. The tuner will handle this better than the >very short whip without a coil. > >It seems to me that a short-whip automatic tuner should have an >inductance in series with the antenna input, maybe a LCL tee network. >I don't know what sort of topology the T-T 247 has but I don't think >anyone is building an LCL tee manual antenna tuner. It'd be easy to do >in an auto tuner though. > >Anyone know the internals of the SGC short whip tuner (the one with the >whip mounted to it)? > >Dan, >N3OX I believe my tuner is CLC, it has two caps and the inductor. -- 73 for now Buck N4PGW Article: 223894 of rec.radio.amateur.antenna From: Buck Subject: Re: TT-247 and 102 whip for mobile antenna ? Message-ID: References: <6na4521tmlo4ipifhhgo0u5dvt43t3l25c@4ax.com> Date: Fri, 28 Apr 2006 22:57:40 -0400 On Fri, 28 Apr 2006 10:52:54 -0700, Richard Clark wrote: >You must have some idea of what band you are going to use it on, what >is it? > >73's >Richard Clark, KB7QHC Thanks, Richard for the comments. I would like to use it for 75-6 meters as I am not worried about 160 meters. I would like to use it on 75 meters, as it is the band most likely to meet the coverage I am interested in, but also to operate all bands as I would like not to change antennas all the time. I have loaded the 20 meter and 40 meter antennas with it to see how it works on other bands, but they really suck!. I don't know if it is the way they are wound or what, but tuning the 20 for six works well, but not with other bands. Going lower doesn't help. As for the mobile vs base antennas, there may be some difference. The problem occurs when using a quarter wave or shorter dipole. However, a quarter wave vertical is a match! This is part of my questioning. Also, the fact that the tuner will be virtually at the antenna rather than the coax, may make some difference, although, technically, I think the coax would lower the reflected power to the tuner. The theory i was hearing was that the loading coil takes all the missing length of antenna and heats up. I can't imagine auto-tuners having as large a coil as this manual tuner. (It uses a wire wrapped around a toroid of some sort. ) I imagine an autotuner uses much smaller inductors tied together thru relays. I am trying to think of a type thurmometer that I could use that wouldn't interact with the tuner to see if it heats up. I will probably test the antenna this weekend if I can get the parts and time.... -- 73 for now Buck N4PGW Article: 223895 of rec.radio.amateur.antenna From: Buck Subject: Re: TT-247 and 102 whip for mobile antenna ? Message-ID: <92m552p0gku2map37b381iomes9r87b58u@4ax.com> References: <6na4521tmlo4ipifhhgo0u5dvt43t3l25c@4ax.com> Date: Fri, 28 Apr 2006 23:07:32 -0400 On Sat, 29 Apr 2006 02:06:48 GMT, Bob wrote: >Not counting the potential tuner problems you mention, my experience is >a 102” whip with no loading will work ok on 10-20m, but on 40m and below >it sucks. >Bob > with no tuning? you get acceptable match to your rig without a tuner, would you explain more? thanks Buck -- 73 for now Buck N4PGW Article: 223896 of rec.radio.amateur.antenna From: Fred Subject: Re: blame the posters not arrl Message-ID: <3lm5521h52e4jgalekjqq6g64e3i59u1mm@4ax.com> References: <22se42d1ndkmbrj99p6675l6k2t16rplk4@4ax.com> <1146238178.410103.29330@y43g2000cwc.googlegroups.com> <1146271643.734737.155940@j73g2000cwa.googlegroups.com> Date: Sat, 29 Apr 2006 03:19:03 GMT On 28 Apr 2006 17:47:23 -0700, "an_old_friend" wrote: > >Fred wrote: >> On 28 Apr 2006 08:29:38 -0700, "an old freind" >> wrote: >> >> > > >> >> You said a mouthful. Oh and I agree with you. It just aint natural! >> >funny it occours outside of man and outside the primates in nature all >> >the time >> >> So you are as stupid as a monkey or a dog? > >no you point? > >it looks like you are here to push your religous agenda and nothing to >with radio If you were smart enough to read you would find out that I do not believe in DOG. I am just picking on you for being a militant pro-gay that is trolling Usenet groups looking for acceptance of his sick lifestyle. Article: 223897 of rec.radio.amateur.antenna From: Buck Subject: Re: TT-247 and 102 whip for mobile antenna ? Message-ID: <45m55219u61f3rj7m46pp5lhuvpmc7nn49@4ax.com> References: <6na4521tmlo4ipifhhgo0u5dvt43t3l25c@4ax.com> Date: Fri, 28 Apr 2006 23:21:42 -0400 On Sat, 29 Apr 2006 02:06:48 GMT, Bob wrote: >Not counting the potential tuner problems you mention, my experience is >a 102” whip with no loading will work ok on 10-20m, but on 40m and below >it sucks. >Bob I would expect it to suck on the lower bands. I am trying to figure out some form of loading that will be cheap and simple to use. I have a 40 meter whip and I guess I could add the 102 to the top for a stinger, but that would make for a long and weak (physically) antenna. 75 mobile sucks under the best of conditions. That much I know. I may have to settle for a 75/80 meter antenna option. I am trying to think of a way to add a base coil that may allow me to tune lower bands more easily without upsetting the higher bands. I don't want to tune the coil itself every time I change bands, but I wouldn't mind bypassing the coil on those times I would rather not tune 80/40. I am very interested in operating 60 meters mobile on a regular basis as well as 20 and up. Buck -- 73 for now Buck N4PGW Article: 223898 of rec.radio.amateur.antenna From: Sum Ting Wong Subject: Re: Lightning suppressor? Message-ID: References: <87slnywtag.fsf@qmc.ph.msstate.edu> Date: Sat, 29 Apr 2006 03:41:56 GMT On 27 Apr 2006 17:24:55 -0500, tclay@qmc.ph.msstate.edu wrote: >>I would like to put an arrestor in the line but recommendations are >>sketchy even from those who sell them. I assume it would be most >>effective at the base of the tower on the ground rod. The drawing in >>the ARRL Antenna Handbook shows the arrestor on a common station >>ground. > >Once you have more than one or two antennas, disconnecting the feedlines >and throwing them out the window gets to be a real pain. > >you probably want to > >a) ground the shield of the coax at the base of the tower, and >b) have a lightning arrestor where the coax enters the house or at >your shack, and >c) connect the grounds of the tower, shack, and power co. together > >I ground the coax shields at the base of my towers, run the coax >underground to the house, and then have lightning arrestors at the >house before the coax goes up to the shack on the 2nd story. > >Tor >N4OGW Don't forget the control wires for your antenna rotator. Seems like all your antennas and control cable(s) entering the shack through arrestors on grounded metal plate is the recommended method these days. You can find some good poop on lightning protection here: http://www.iceradioproducts.com/thorshammer.htm http://www.iceradioproducts.com/10.html S.T.W. Article: 223899 of rec.radio.amateur.antenna From: richardharrison@webtv.net (Richard Harrison) Subject: Re: Velocity Factor and resonant frequency Date: Fri, 28 Apr 2006 23:06:24 -0500 Message-ID: <17735-4452E640-132@storefull-3251.bay.webtv.net> References: <1146269331.884979.12810@j73g2000cwa.googlegroups.com> Dan, N3OX wrote: "Also should have said "a few turns over a few inches for a "TWT OPERATING" at microwave frequencies". That`s interesting. John D. Kraus invented the axial-mode helix antenna after attending a lecture on traveling wave tubes given by a famous scientist visiting Ohio tate University. Kraus asked the visitor if he thought the helix could be used as an antenna. The visitor said no, so Kraus went home, wound seven turns one wavelength in circumference and discovered it made a sharp beam off the open end when he used a ground plane across the driven end. The story appears on page 222 of Hraus` 3rd edition of "Antennas". Lenkurt described operation of the traveling wave tube in its August 1965 edition of the "Demodulator". Here is an excerpt: "The signal to be amplified by the tube is coupled into the gun end of the helix. This RF signal travels as a surface wave around the turns of the helix, toward the collector, at about the velocity of light. The forward or axial velocity of the signal is slower, of course, because of the pitch and diameter of the helix. This forward movement of the wave is analogous to the travel of a finely threaded screw where many turns are required to drive it into position. The signal wave generates an axial electric field which travels with it along the longitudinal axis of the helix. This alternating electric field interacts or velocity modulates the electrons in the beam." Terman`s description in the 1955 edition of "Electronic and Radio Engineering" starts on page 678 and is very similar to Lenkurt`s. i`d bet that it is more than coincidental. Kraus says of his new helical antenna on page 223 of his 3rd edition of "Antennas": "At a low frequency (helix circumference about lambda/2) there was almost a pure standing wave (VSWR goes to infinity) all along the helix (outgoing and reflected waves nearly equal) (Fig. 8-3a)--." Surely an antenna loading coil resembles Kraus` low-frequency helix. It has an open-circuit whip producing a reflection into one end. The circumference is well below 1/2-wavelength, giving a current distribution such as shown in Fig. 8-3a for a frequency below the axial mode of operation. Fig. 8-3c shows uniform outgoing and reflected currents over the middle section of the helix. Kraus` figures were produced from actual measurements. Best regards, Richard Harrison, KB5WZI Article: 223900 of rec.radio.amateur.antenna From: Roy Lewallen Subject: Re: Velocity Factor and resonant frequency Date: Fri, 28 Apr 2006 23:01:54 -0700 Message-ID: <12560ajs2oc286f@corp.supernews.com> References: <1146269331.884979.12810@j73g2000cwa.googlegroups.com> <17735-4452E640-132@storefull-3251.bay.webtv.net> Richard Harrison wrote: > . . . > Surely an antenna loading coil resembles Kraus` low-frequency helix. It > has an open-circuit whip producing a reflection into one end. The > circumference is well below 1/2-wavelength, giving a current > distribution such as shown in Fig. 8-3a for a frequency below the axial > mode of operation. > . . . So does this mean if we put a current into one end of the inductor I described, it'll take about 40 ns for current to reach the other end? So we should expect a phase delay in the current of 90 degrees at 6.15 MHz, or about 15 degrees at 1 MHz, from one end to the other? What good are all these books if the information can't be used to solve a simple problem? Roy Lewallen, W7EL Article: 223901 of rec.radio.amateur.antenna From: switcher Subject: question about caps in tuning loops .. Date: Sat, 29 Apr 2006 09:43:09 +0200 Message-ID: when the metal plates move and more surface is used/covered by the cap, is the capacitance higherb (farads) ?? I see that with loop ant, the more the plates cover each other, the lower the tuned freq is ... So with a high cap, you could make an ant with less turns of wire ... Sometimes I find a large cap (1 F) at flea markets, for 1 euro/$ or so. They cost 100 or so new. Would they make sense ?? -- een appeltje te schillen met http://applefaulty.be http://users.fulladsl.be/spb13810/bwnl.htm Breng je iMac G5 terug (ik wil binnen 2 jaar geen defecte 2de hands Apple kopen) http://www.apple.com/nl/support/imac/repairextensionprogram/ Article: 223902 of rec.radio.amateur.antenna From: Alien Subject: Re: Coax Bulkhead References: Message-ID: Date: Sat, 29 Apr 2006 10:48:46 GMT In article , "west" wrote: > Is there a place on the net, in a book, etc. that I can see examples & > diagrams of a coax bulkhead? My house sits on a slab and I want to run about > 4 or 5 coax cables, rotor cable, AC & DC source all going from the shack to > my tower. In Florida lightning is a major concern so the bulkhead will have > to have coax & other type of arrestors. All this is grounded to a copper > ground rod & the cables, of course, to my shack. I would like this outside > "box" nicely & neatly dressed & labeled so it's easy to disconnect & not an > eye sore. I searched the Ham books and many Internet sights to no avail. > Anybody? Thank you. > > west, AF4GC Checkout I.C.E here: http://www.iceradioproducts.com/ They have just what you're looking for. I don't work for them, but I have quite a few of their products. They build good stuff. Article: 223903 of rec.radio.amateur.antenna From: Buck Subject: Re: TT-247 and 102 whip for mobile antenna ? Message-ID: References: <6na4521tmlo4ipifhhgo0u5dvt43t3l25c@4ax.com> Date: Sat, 29 Apr 2006 07:55:47 -0400 On Fri, 28 Apr 2006 22:07:00 -0700, Richard Clark wrote: >On Fri, 28 Apr 2006 22:57:40 -0400, Buck wrote: >>I would like to use it for 75-6 >>meters as I am not worried about 160 meters. I would like to use it >>on 75 meters, as it is the band most likely to meet the coverage I am >>interested in, > >Hi Buck, > >All reports of short, mobile antennas on 80M generally cry crippled. >That is, unless, they are augmented by center loads under top hats a >dozen feet high or more. Even then, hardly remarkable unless you can >stand to be down 2 S-Units out the gate. For some, this knowledge is >a killer. For others who ignore it, they simply work those who can >hear them. I realize this. I have used a Hustler on 75 before. I was definitely a weak signal station. I can only imagine that a tuned whip would generate similar results, or more likely, poorer results. > >>but also to operate all bands as I would like not to >>change antennas all the time. I have loaded the 20 meter and 40 meter >>antennas with it to see how it works on other bands, but they really >>suck!. > >Well, again, you are short on details. These two antennas (I presume >you have introduced two more to the discussion) may be air cooled >resistors for all their qualities you suggest. You might find an >object lesson here. There are a total of four antennas I have mentioned in here for comparison sake. The Hustler, just mentioned above, the 102 whip with a possible 2 foot extension, and two Antenna Specialists (AS) (look exactly like HamSticks). I haven't had the Hustler for over a decade. I will introduce another antenna in this message later. The AS antennas are thin fiberglass poles with long stingers on the top. The fiberglass poles, of course, have copper wound around them >from bottom to top, above which is a whip (stinger) about the same length as the pole. The hustler was a center loaded trap that was several inches in diameter and about 10-12 inches tall (the trap part) with a stinger on top. (You are probably familiar with the Hustler.) I also have a Volvo brand CB whip. It is a thin fiberglass whip similar to the bottom portions of the AS antennas, but it does not have a stinger. Like the AS antennas, the fiberglass has copper wire wound from bottom to top with the top tightly wound and the bottom section loosely wound. There is no stinger on top of the CB antenna. I previously did a little experimenting with the two AS antennas and the Volvo CB antenna (I don't have the 102 whip yet.) I used the tuner to compare receive signals on various active bands. the results weren't very good. Basically, each antenna performed best on the frequencies for which they were designed (no big surprise here) but they performed terribly on any other band. In fact, they were not even acceptable for use on other bands. The signal strength on 20 meters, for example went from s-9 on the 20 AS antenna to less than s-2 on the other antennas. I know others who have used the 102 steel whip/auto-tuner combination that I have talked to never complained that they only received s-2 signals with the system. Therefore, my theory is that the winding of the coil on the fiberglass poles is adversely affecting the radiation on out-of-band operation. I am hoping that the steel whip, with or without the extension, will perform better on all bands than any of these antennas tested. I realize it is a compromise but the loss of an s-unit or two in exchange for all band coverage for my mobile without having to switch antennas or get out of the car and change taps is an acceptable trade-off. Remember, too, that in the original post, money is a big issue. The purchase of a screwdriver (the best known mobile antenna design for all band coverage) is not an option at this time. My theory is that I should be able to mimic the 102 whip/auto-tuner results using a manual tuner. My question is whether or not the tuner itself can hold up to the task without being damaged. > >>I don't know if it is the way they are wound or what, but >>tuning the 20 for six works well, but not with other bands. Going >>lower doesn't help. > >Barring details.... I think I addressed that above, the fiberglass poles are wrapped tightly at the top and then loosely to the bottom, a stinger extends >from the tops of the AS antennas, and the Volvo antenna doesn't have a stinger. > >>As for the mobile vs base antennas, there may be some difference. The >>problem occurs when using a quarter wave or shorter dipole. > >Mobile quarterwave dipole? base. The suggestion I was given was not to use the antenna tuner on a 20 meter dipole to tune a 40 meter frequency. This would be a 1/4 wave dipole on 40 meters. I don't know what the impedance of such an antenna would be, but I do know that a 1/4 wave vertical is a reasonable match. We never discussed the use of the tuner in the mobile. > >>However, >>a quarter wave vertical is a match! This is part of my questioning. > >Aside from this being natural, what could the question be? > >>Also, the fact that the tuner will be virtually at the antenna rather >>than the coax, may make some difference, although, technically, I >>think the coax would lower the reflected power to the tuner. > >Many antennas are designed with a match external to them, but quite >close by. Why would this be detrimental? Even more, many antennas >are built with the match as part of them. They go by many names, >Gamma being one. Certainly nothing is lost in their use. > >>The theory i was hearing was that the loading coil takes all the >>missing length of antenna and heats up. I should have clarified that this statement. The internal inductor of the tuner makes up the missing length of the antenna and heats up which can cause damage to the antenna tuner's inductor. This is how it was presented to me, or how I understood it. Again, the discussion was using the tuner to tune short dipoles to transmit on lower frequencies. > >Dare I say you can't trust everything you hear (read here)? > >Myself, I taught RF communications in the Navy and had no trouble >whatever with the concept that a coil replaces the electrical length >missing in a short antenna. However, the Navy was never a slave to >fashion nor strict interpretation in this matter, and it was enough to >observe this quid-pro-quo as symbolic, and not literal. > >> I can't imagine auto-tuners >>having as large a coil as this manual tuner. (It uses a wire wrapped >>around a toroid of some sort. ) I imagine an autotuner uses much >>smaller inductors tied together thru relays. > >Indeed. > >>I am trying to think of a type thurmometer that I could use that >>wouldn't interact with the tuner to see if it heats up. > >Yuri might suggest aquarium thermometers (Liquid Crystal) - but you >would have to make sure the entire surface fit the entire strip (or >versa vice). If you have a very old digital camera, then they were >sensitive to IR. You could take a picture in the dark and resolve hot >spots. > >>I will probably test the antenna this weekend if I can get the parts >>and time.... > >Further reports would be interesting. > I have been scheduled to work this weekend. I hope to be off Sunday, If I can, I will try testing the whip idea using the side mount on the van and if it appears to be promising, I will drill the holes in the roof to mount the whip there near the radio and tuner. >73's >Richard Clark, KB7QHC 73 for now -- 73 for now Buck N4PGW Article: 223904 of rec.radio.amateur.antenna From: Buck Subject: Re: TT-247 and 102 whip for mobile antenna ? Message-ID: <43l652958kmtlj60lgmtsi3ahgfs6snt5m@4ax.com> References: <6na4521tmlo4ipifhhgo0u5dvt43t3l25c@4ax.com> <92m552p0gku2map37b381iomes9r87b58u@4ax.com> Date: Sat, 29 Apr 2006 08:04:34 -0400 On Fri, 28 Apr 2006 23:07:32 -0400, Buck wrote: >On Sat, 29 Apr 2006 02:06:48 GMT, Bob wrote: > >>Not counting the potential tuner problems you mention, my experience is >>a 102” whip with no loading will work ok on 10-20m, but on 40m and below >>it sucks. >>Bob >> >with no tuning? you get acceptable match to your rig without a tuner, >would you explain more? > >thanks >Buck I just re-read your statement. Are you saying the whip without a loading coil used thru a tuner? My first thoughts were you meant without a tuner. I expect that 40 and below will be a bit poor. I hope to find a compromise of sorts where I can add a loading coil, but only change it when I want to operate 40-80 meters, sort of a switch between the higher and lower bands as opposed to setting it for each band. The alternative may be to have two antennas, one for the lower bands, set as needed per band, and one for the upper bands that only needs tuning with the tuner. If I am lucky, I may be able to have one with a loading coil that tunes all the lower bands relatively efficiently and the whip for the upper bands. I can deal with two antennas, I have a switch but my problem right now is I have separate 40, 20, 11, 10, and 6 meter antennas. If I want to change bands, I have to replace each antenna. Likewise, if I want to add a band, I have to buy more antennas. I just want to simplify my operation for when I am mobile. I have a 135 foot dipole with 300 ohm feed that I can toss up in the trees for portable operation when I want to be efficient or for emergency operations, but for moving, I don't want to pull off the highway and get out of my car to change antennas every time I want to change bands. Thanks for the input. Buck -- 73 for now Buck N4PGW Article: 223905 of rec.radio.amateur.antenna From: Buck Subject: Re: May 1st 2006, Civil War Begins Message-ID: References: Date: Sat, 29 Apr 2006 08:06:08 -0400 On Fri, 28 Apr 2006 17:49:18 -1000, stananger < stananger@********.***> wrote: >May 1st 2006, Civil War Begins > >On May 1st 2006 The "Great American Boycott" also known as the "Day without >immigrants" is scheduled to occur. Participant's stated goals are a general >strike, No Work, No School, No Sales, and No Buying. These people want to >shut down individual cities, all across the nation, thereby impacting the >country as a whole. >Make no mistake about it, this is not just simple protesting, protesting >with the goal of causing financial harm is Economic Terrorism plain and >simple - and those people who participate are economic terrorists. >By shutting down certain cities, or even portions of cities, these >protestors will be : > Keeping children out of school, > Hampering the abilities of local law enforcement to enforce the law, > Hampering the abilities of first responders to respond to car accidents, >fires, people having heart attacks, and hampering their ability to >transport them to the hospital. > Hampering the abilities of local mass transit systems to operate properly. > Causing financial harm to local businesses iregardless of whether or not >those businesses have harmed them, resulting in a nationwide economic >impact. > Advocating the breaking of our laws by demanding, yes demanding, that >illegal immigrants be given amnesty. > > > ter·ror·ism -"The unlawful use or threatened use of force or violence by a >person or an organized group against people or property with the intention >of intimidating or coercing societies or governments, often for ideological >or political reasons." - American Heritage® Dictionary of the English >Language, Fourth Edition >How can you fight back? >Ensure that your children go to school, and stay there on this day. > Purposely go and buy products and services in those cities affected by the >protestors - gas up your car, go see a movie, go grocery shopping, buy a >little more than you would have any other day. Counter their 'protest' with >a positive economic impact in those areas affected. > Perhaps you might also consider making a donation to those organizations >seeking to secure our borders on this day as well. Show these terrorists >that you can and will fight back! >While the current situation is one of mass irresponsible action, causing >financial harm across the nation, it will inevitably escalate into violence >and deaths if these sorts of activities continue. >Does this constitute a civil war? Perhaps not yet, but its clearly heading >in that direction, this may just be the first battle. and what band and mode will this protest take place? -- 73 for now Buck N4PGW Article: 223906 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Velocity Factor and resonant frequency References: <1146269331.884979.12810@j73g2000cwa.googlegroups.com> <17735-4452E640-132@storefull-3251.bay.webtv.net> <12560ajs2oc286f@corp.supernews.com> Message-ID: Date: Sat, 29 Apr 2006 14:03:17 GMT Roy Lewallen wrote: > So does this mean if we put a current into one end of the inductor I > described, it'll take about 40 ns for current to reach the other end? So > we should expect a phase delay in the current of 90 degrees at 6.15 MHz, > or about 15 degrees at 1 MHz, from one end to the other? Equation (32) at http://www.ttr.com/TELSIKS2001-MASTER-1.pdf answers that question. The VF is about double the "round and round the coil" calculated value and the VF changes with frequency. -- 73, Cecil http://www.qsl.net/w5dxp Article: 223907 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: TT-247 and 102 whip for mobile antenna ? References: <6na4521tmlo4ipifhhgo0u5dvt43t3l25c@4ax.com> Message-ID: Date: Sat, 29 Apr 2006 14:19:33 GMT Buck wrote: > I have used a Hustler on 75 before. I was definitely > a weak signal station. I can only imagine that a tuned whip would > generate similar results, or more likely, poorer results. Following are the summarized normalized combined results of three 75m mobile antenna shootouts held in California during the 1980's. 0 dB - (Reference) Bugcatcher or Screwdriver with large top hat -2 dB - Bugcatcher or Screwdriver with no top hat -5 dB - 8.5' whip with bugcatcher base loading coil -6 dB - Bugcatcher with Stainless Steel Loading Coil -8 dB - Hustler High Power system -9 dB - Outbacker -12 dB - Hamstick -12 dB - 11.5' whip with SGC-230 autotuner -14 dB - 8.5' whip with SGC-230 autotuner (estimated, not measured) -- 73, Cecil http://www.qsl.net/w5dxp Article: 223908 of rec.radio.amateur.antenna From: John Ferrell Subject: Re: Lightning suppressor? Message-ID: References: <87slnywtag.fsf@qmc.ph.msstate.edu> Date: Sat, 29 Apr 2006 14:38:22 GMT The low response to the question leads me to believe that many (most?) have reached the same conclusions as I have. That is: Isolating the incoming antenna and control cables is the preferred method. Providing a low impedance path to ground in the radio shack is undesirable. Further, adding an extra ground point in the system wherever is a lightning no-no and introduces unknowns into the RF scheme. Especially if one chooses to not run a 1:1 swr. In my case the base of the tower has its own ground and is connected to the structure lightning protection. I will continue to disconnect and connect cables. If an application that requires operation during electrical storms is the norm, it becomes a different circumstance. I will keep an open mind to the question though! John W8CCW On Sat, 29 Apr 2006 03:41:56 GMT, Sum Ting Wong wrote: >On 27 Apr 2006 17:24:55 -0500, tclay@qmc.ph.msstate.edu wrote: > >>>I would like to put an arrestor in the line but recommendations are >>>sketchy even from those who sell them. I assume it would be most >>>effective at the base of the tower on the ground rod. The drawing in >>>the ARRL Antenna Handbook shows the arrestor on a common station >>>ground. John Ferrell W8CCW Article: 223909 of rec.radio.amateur.antenna From: "jimmiefender@bellsouth.net" References: <_7CYf.908089$xm3.833232@attbi_s21> <123605h66a6vld1@corp.supernews.com> Subject: Re: Antenna RF choke questions Message-ID: <9qL4g.23626$iB2.16352@bignews4.bellsouth.net> Date: Sat, 29 Apr 2006 11:16:32 -0400 "Jim Higgins" wrote in message news:ak0832tvu0s20dnqp9ihk333a71k2s1lfv@4ax.com... > On Tue, 04 Apr 2006 20:05:34 -0700, Richard Clark > wrote: > >>On Wed, 05 Apr 2006 02:46:14 GMT, "AK" wrote: >> >>>Reg thinks it's the tape's lack of water sealing. I have been using some >>>putty-like sealer on my 239s lately, but it is a mess to clean off when >>>disconnecting and re-connecting the coax - as sometimes required. >> >>Hi OM, >> >>Lay down a layer of tape first. >>Seal it with the sealer (much cheaper from flower shops). >>Lay down another layer of tape. > > > For the past 20 years I've used the same piece of coax running to a > ground mounted vertical antenna. The coax runs across the top of the > ground. The threads of the PL259/SO239 connection at the antenna are > sealed with plumber's grease on the threads of the connector. The > barrel of the PL259 behind the threaded sleeve is wrapped with high > quality white vinyl tape extending about 4 inches up the coax. I > remove the PL259 every week or so in the summer to move the coax while > I mow the lawn. About 6 months ago I figured it was time to inspect > things so I cut off the PL259, expecting to find corrosion requiring > cutting the coax back to find clean shield or requiring coax > replacement. Not so. I found clean copper shield at the cut end. The > coax jacket wasn't at all brittle so I soldered on a new PL259, > greased it and the SO239, and figure I'm good to go for a few more > years. > > Jim Higgins, KB3PU Same experience here, I grease eveything up with DC4 dielectric grease, not only does it keep the water out it acts like anti-sieze to make it come apert easy and wrap every thing in some good vinyl tape. One thing I have done a few times is to place some steel fishing leader under the tape. Whenever I want to open the splice just pull on the leader and it slices it open. I still like to use heatshrink over the tape to give the tape some UV protection. I never trust heatshrik alone. I have had bad experience with this. Article: 223910 of rec.radio.amateur.antenna From: "jimmiefender@bellsouth.net" References: <_7CYf.908089$xm3.833232@attbi_s21> Subject: Re: Antenna RF choke questions Message-ID: Date: Sat, 29 Apr 2006 11:22:28 -0400 "Reg Edwards" wrote in message news:f8-dnb2ureSnu67ZRVnygw@bt.com... > > "AK" wrote in message > news:_7CYf.908089$xm3.833232@attbi_s21... >> Putting together a new Cushcraft A4S (10,15, 20m) beam. >> >> Cushcraft recommends using an 8-turn, 6-inch diameter RG8U coax > cable coil >> as an RF choke for feeding the driven element. HyGain suggested the > same >> thing for the TH2MK3 antenna I used many years ago -- only using 12 > turns of >> RG8 (with the 6-inch outside diameter), rather than 8 turns. I have > a few >> questions on the best way to do this. >> >> 1) Is it fair to assume that the more turns the better? >> >> 2) Should the coil be as close to the antenna feedpoint as possible, > or is a >> foot or two of straight coax between the antenna input and the coil > OK? >> >> 3) Would placing the coax coil around the mast (instead of taping > one side >> of the coil to the mast as suggested) be a bad thing to do? >> >> 4) Is there a good website or book that describes the technical > tradeoffs of >> a coax RF choke? ( I am sort of wondering if the choke can be > skipped. Some >> time ago, I used a W2AU balun on a multiband dipole. All it did was > create >> TVI when I went on 10 meters. Took the balun out, and the resonant > points >> didn't change. I figured that if there were antenna currents on the > coax, >> they would bring down the resonant frequency without the balun. > Since that >> didn't happen, I figured the balun wasn't helping - - but balun core >> saturation at 30 MHz (with the KW on) was what was racking up the > TVs.) >> >> 5) One last question - not having to do with the coax RF choke: >> Cushcraft "operating tips" say to not use vinyl tape on SO239 or > PL-239 >> connectors. Why? What problem would the tape cause?? >> >> Thanks for any info - AK >> > ========================================= > > A choke made of 8 turns, 6 inches diameter, has a resonant frequency > around 21 MHz and has an impedance greater than 1000 ohms in the 20 > meter and 10 meter bands. > > Chokes are best wound neatly in the form of a single layer solenoid. > Jumble wound choke coils can have funny effects. > > For design of chokes made with coax cable download program SELFRESS > from website below and run immediately. > ---- > ........................................................... > Regards from Reg, G4FGQ > For Free Radio Design Software go to > http://www.btinternet.com/~g4fgq.regp > ........................................................... > > I like to wind them on a piece of PVC pipe tie wrapping or lacing the turns to the pipe. Article: 223911 of rec.radio.amateur.antenna From: Bob Subject: Re: TT-247 and 102 whip for mobile antenna ? References: <6na4521tmlo4ipifhhgo0u5dvt43t3l25c@4ax.com> <92m552p0gku2map37b381iomes9r87b58u@4ax.com> Message-ID: <6OL4g.10069$Lm5.1814@newssvr12.news.prodigy.com> Date: Sat, 29 Apr 2006 15:40:50 GMT Used various SGC tuners and Icom AH-4. Also tried both of SGCs dual loaded whips with varying results. The longer two piece unit worked surprisingly well 80-10m years ago when conditions were better, even had some fantastic 160m mobile contacts with it. The single 7ft version lacks on 40 and especially 80m compared to the two piece whip but compared to an unloaded 102” CB whip, it makes the CB whip look like a dummy load on 40m and below. This is all with an SGC-230 feeding them. Bob Buck wrote: > On Sat, 29 Apr 2006 02:06:48 GMT, Bob wrote: > >> Not counting the potential tuner problems you mention, my experience is >> a 102” whip with no loading will work ok on 10-20m, but on 40m and below >> it sucks. >> Bob >> > with no tuning? you get acceptable match to your rig without a tuner, > would you explain more? > > thanks > Buck Article: 223912 of rec.radio.amateur.antenna From: Bob Miller Subject: Re: Coax Bulkhead Message-ID: <4i2752d8bb5u101l4p317tk0dc63e8qt47@4ax.com> References: Date: Sat, 29 Apr 2006 15:50:08 GMT On Wed, 26 Apr 2006 04:12:09 GMT, "west" wrote: >Is there a place on the net, in a book, etc. that I can see examples & >diagrams of a coax bulkhead? My house sits on a slab and I want to run about >4 or 5 coax cables, rotor cable, AC & DC source all going from the shack to >my tower. In Florida lightning is a major concern so the bulkhead will have >to have coax & other type of arrestors. All this is grounded to a copper >ground rod & the cables, of course, to my shack. I would like this outside >"box" nicely & neatly dressed & labeled so it's easy to disconnect & not an >eye sore. I searched the Ham books and many Internet sights to no avail. >Anybody? Thank you. > >west, AF4GC > FWIW, the latest paper catalog from RadioWorks shows adjustable plexiglass inserts that will fit the bottom of any window, and they will outfit the insert with feedthroughs for any type of coax or wire plugs that you need. bob k5qwg Article: 223913 of rec.radio.amateur.antenna From: richardharrison@webtv.net (Richard Harrison) Subject: Re: Velocity Factor and resonant frequency Date: Sat, 29 Apr 2006 12:13:42 -0500 Message-ID: <10935-44539EC6-55@storefull-3258.bay.webtv.net> References: <12560ajs2oc286f@corp.supernews.com> Roy, W7EL wrote: "What good are all the books if the information can`t be used to solve a simple problem?" Many problems fit examples in the books. Some don`t. Implications in my case are sometimes slow to sink in. An example is what Kraus writes on page 227 of the 3rd edition of "antennas": "Thus, a helix combines the geometric forms of a straight line, a circle, and a cylinder." Cecil says that RF on a helix may take a short-cut. He may be right. Why would not a wave deviate from the round and round path on a coil and sweep at least in part directly along the cylindrical length? It may be a case for experimentation with a variety of lengths, pitches, and circumferences. Best regards, Richard Harrison, KB5WZI Article: 223914 of rec.radio.amateur.antenna From: John Ferrell Subject: Re: Lightning suppressor? Message-ID: References: <87slnywtag.fsf@qmc.ph.msstate.edu> Date: Sat, 29 Apr 2006 18:18:18 GMT Thank you. Lots to read & consider there. It will take me a while to digest it. Some how I managed to miss Polyphaser in my searching. John, W8CCW On Sat, 29 Apr 2006 13:25:25 -0400, Gary Schafer wrote: >I would follow the advice of TCLAY a couple of posts back. I would add >that there should also be a low impedance ground at the shack entrance >where the lightning arrestor is placed. At that same point the rest of >the radio equipment should be grounded. One common ground point for >all. The tower ground should also be run over to that common ground >point. >The AC power that supplies your equipment should have protection >devices that connect to the common single point ground also. > >All grounds in the system should be tied together. > >The idea of the single point ground is to have all equipment go up in >voltage together if there is a lightning strike and fall together. >This eliminates voltage differences between parts of equipment that >causes damage. > >The coax shield should be grounded to the tower at the top and the >bottom of the tower. The tower should have a substantial ground system >of several ground rods and radials. > >Look at the Polyphaser site again. They show how a single point ground >system should be installed. > >73 >Gary K4FMX > > >On Sat, 29 Apr 2006 14:38:22 GMT, John Ferrell > wrote: > >>The low response to the question leads me to believe that many (most?) >>have reached the same conclusions as I have. >> >>That is: >>Isolating the incoming antenna and control cables is the preferred >>method. Providing a low impedance path to ground in the radio shack is >>undesirable. >> >>Further, adding an extra ground point in the system wherever is a >>lightning no-no and introduces unknowns into the RF scheme. Especially >>if one chooses to not run a 1:1 swr. >> >>In my case the base of the tower has its own ground and is connected >>to the structure lightning protection. I will continue to disconnect >>and connect cables. >> >>If an application that requires operation during electrical storms is >>the norm, it becomes a different circumstance. >> >>I will keep an open mind to the question though! >>John W8CCW >> >>On Sat, 29 Apr 2006 03:41:56 GMT, Sum Ting Wong >> wrote: >> >>>On 27 Apr 2006 17:24:55 -0500, tclay@qmc.ph.msstate.edu wrote: >>> >>>>>I would like to put an arrestor in the line but recommendations are >>>>>sketchy even from those who sell them. I assume it would be most >>>>>effective at the base of the tower on the ground rod. The drawing in >>>>>the ARRL Antenna Handbook shows the arrestor on a common station >>>>>ground. >>John Ferrell W8CCW John Ferrell W8CCW Article: 223915 of rec.radio.amateur.antenna From: Allisonnospam@nouce.bellatlantic.net Subject: Re: J_Pole Trials and Tribulations Message-ID: References: <1146008591.641742.237030@y43g2000cwc.googlegroups.com> <4tjt42lg6k5ustfmiljfkpiqdle084d0iq@4ax.com> <96N4g.77517$dW3.54166@newssvr21.news.prodigy.com> Date: Sat, 29 Apr 2006 18:45:09 GMT I happen to like them as they can be made from common materials with excellent ruggedness. As to the other claims of fantastic gain and all, it's bogus. It's a vertical halfwave endfed and the gain is 2.4ish DB over a dipole and that's all. If executed correctly it will be better than a 1/4wl groundplane but not by any fanstastic amount. For many applications that is a "good enough" antenna. Allison On Sat, 29 Apr 2006 17:10:29 GMT, Bob wrote: >The J-pole crowd seems to tout fantastic claims about this antenna and I >have never been impressed. Many people have tested the J-pole against >other easy to make antennas and the end fed half wave J-pole usually >does not stand up to even it’s brother, the center fed half wave dipole. >I assume the decrease in performance is due to mistakes in assembling >and tuning the matching section. Here is a link to a group that tested >some J-poles against other antennas in the CA desert and the J-pole lost >to even simple 1/4 wave ground plane types. >www.geocities.com/SiliconValley/2775/anttest.html >My point is, why not make a simple ground plane for the attic that may >not get bothered by surroundings as much as the J-pole. >Bob > > >Buck wrote: >> On 25 Apr 2006 16:43:11 -0700, jgboyles@aol.com wrote: >> >>> jimbo wrote: >> SNIP >>>> jimbo - AJ7IM >>> Hi Jimbo, it has been my experience, and everybody else's that an >>> indoor or attic J-pole is unpredictable. A high impedance end fed >>> antenna in an attic environment will be hard to predict. Moving it one >>> foot can effect things. >>> You might consider the SO-239 ground plane. It can be built and >>> tuned in 30 minutes, is 50 ohms, so it will not be so concerned about >>> its environment. Likely you could not tell a difference in performance >>>from a J-pole especially if they are both in the attic. >>> Oh yes, the standard-if the SWR is below 3.0, don't worry about it. >>> Gary N4AST >> >> >> I started building dipole antennas. they can be mounted horizontal or >> vertical and easily moved around. I use cpvc with a dipole wire >> inside and a coax-choke balun. They work quite well. >> >> Just another option. Article: 223916 of rec.radio.amateur.antenna From: Roy Lewallen Subject: Re: Velocity Factor and resonant frequency Date: Sat, 29 Apr 2006 12:20:14 -0700 Message-ID: <1257f3h64h9dn21@corp.supernews.com> References: <12560ajs2oc286f@corp.supernews.com> <10935-44539EC6-55@storefull-3258.bay.webtv.net> So is that a "yes", or "no"? Roy Lewallen, W7EL Richard Harrison wrote: > Roy, W7EL wrote: > "What good are all the books if the information can`t be used to solve a > simple problem?" > > Many problems fit examples in the books. Some don`t. Implications in my > case are sometimes slow to sink in. An example is what Kraus writes on > page 227 of the 3rd edition of "antennas": > "Thus, a helix combines the geometric forms of a straight line, a > circle, and a cylinder." > > Cecil says that RF on a helix may take a short-cut. He may be right. Why > would not a wave deviate from the round and round path on a coil and > sweep at least in part directly along the cylindrical length? It may be > a case for experimentation with a variety of lengths, pitches, and > circumferences. > > Best regards, Richard Harrison, KB5WZI > Article: 223917 of rec.radio.amateur.antenna From: Fred Subject: Re: blame the posters not arrl Message-ID: References: <22se42d1ndkmbrj99p6675l6k2t16rplk4@4ax.com> <1146238178.410103.29330@y43g2000cwc.googlegroups.com> <1146271643.734737.155940@j73g2000cwa.googlegroups.com> <3lm5521h52e4jgalekjqq6g64e3i59u1mm@4ax.com> <1146333073.590407.297500@i39g2000cwa.googlegroups.com> Date: Sat, 29 Apr 2006 19:28:28 GMT On 29 Apr 2006 10:51:13 -0700, "an_old_friend" wrote: > >Fred wrote: >> On 28 Apr 2006 17:47:23 -0700, "an_old_friend" >> wrote: >> >> > >> >Fred wrote: >> >> On 28 Apr 2006 08:29:38 -0700, "an old freind" >> >> wrote: >> >> >> >> > >> > >> >> >> You said a mouthful. Oh and I agree with you. It just aint natural! >> >> >funny it occours outside of man and outside the primates in nature all >> >> >the time >> >> >> >> So you are as stupid as a monkey or a dog? >> > >> >no you point? >> > >> >it looks like you are here to push your religous agenda and nothing to >> >with radio >> >> If you were smart enough to read you would find out that I do not >> believe in DOG. >I never stated you did >> I am just picking on you for being a militant pro-gay >> that is trolling Usenet groups looking for acceptance of his sick >> lifestyle. > >hardly you don't know what miliatant is > >you are psuhing you milltant religionous agenda where it desn't belong. >you have the right to do that, as I have the right to post what I see >fit >your problem is that you can't face the fact I have the same rights as >you do > >you want an end to defense of My Bisexaulity it can be had easiily > >you mustb( and the rest must refrain from atacking ti and refrain from >using the cry or "faggot" as an arguement in the NG > >it is that simple but the likes of you have proven you can't do it How many times do I have to tell you that I am an atheist? You can support and defend your faggotry all you want, but this is not the forum for that sick shit. You have no right to harass people in rec.radio.cb or any other newsgroup so suck on that you stupid turd pusher. Article: 223918 of rec.radio.amateur.antenna From: Roy Lewallen Subject: Re: J_Pole Trials and Tribulations Date: Sat, 29 Apr 2006 12:31:44 -0700 Message-ID: <1257fp394gu7t3d@corp.supernews.com> References: <1146008591.641742.237030@y43g2000cwc.googlegroups.com> <4tjt42lg6k5ustfmiljfkpiqdle084d0iq@4ax.com> <96N4g.77517$dW3.54166@newssvr21.news.prodigy.com> Allisonnospam@nouce.bellatlantic.net wrote: > I happen to like them as they can be made from common materials with > excellent ruggedness. As to the other claims of fantastic gain and > all, it's bogus. It's a vertical halfwave endfed and the gain is > 2.4ish DB over a dipole and that's all. If executed correctly it > will be better than a 1/4wl groundplane but not by any fanstastic > amount. For many applications that is a "good enough" antenna. > > Allison What's the mechanism which gives this half wave antenna 2.4 dB gain over a half wave dipole? Modeling shows the gain to be the same as a dipole, if you can manage to keep the current on the outside of the feedline to a small value. If you can't, the gain in the horizontal direction typically becomes less than a dipole. Roy Lewallen, W7EL Article: 223919 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Missing Degrees in Mobile Antennas? References: <9vp252pqm2fues06g4bq2kq0r0s6mt1ed3@4ax.com> <44517fdb$0$1010$39cecf19@news.twtelecom.net> <445184bf$0$1018$39cecf19@news.twtelecom.net> <1146236524.933305.75290@j33g2000cwa.googlegroups.com> <1146320344.271655.25720@y43g2000cwc.googlegroups.com> <8HL4g.77473$dW3.15538@newssvr21.news.prodigy.com> <1146328640.915773.282060@i40g2000cwc.googlegroups.com> Message-ID: Date: Sat, 29 Apr 2006 19:36:54 GMT w8ji@akorn.net wrote: I'm going to ask a couple of technical question at the beginning rather than getting them trimmed and ignored in the body: 1. You seem ready to admit that there is 10 degrees of delay through a 10 degree long stinger. Yet, if you measured that delay using standing wave current phase, you would measure a zero phase shift through the stinger. Why aren't you arguing that there is no phase shift in the stinger? 2. There is no appreciable standing wave current phase shift from feedpoint to the tip of the stinger in a 75m mobile bugcatcher antenna. To be consistent, don't you have to argue that the 75m mobile bugcatcher antenna is zero degrees long? > Cecil Moore wrote: > So you are saying the loading coil is "7's of feet long". Is that > correct? Compared to a straight wire at 4 MHz, yes, that's what I am saying. A 75m bugcatcher coil uses about 42 feet of wire. The delay through that coil is *roughly* equal to about half that number of feet of straight wire. The reason it is not equal to 42 feet of straight wire is the flux coupling between the coils. >>Your assertion that nearly 100% of the coils link >>nearly 100% of the total flux is unrealistic. > > I never said that. But it would necessarily have to be true for the velocity factor of the coil to be anywhere near 1.0 and you did say that. > What's your point in making that switch? We were talking about loading > coils, now you are switching to stubs. Why? THE EFFECT EXISTS WHETHER THE COIL EXISTS OR NOT. Which indicates it is the nature of standing wave current, not coils, that you do not understand. The standing wave current phase is unchanging whether a coil exists or not. ONE CANNOT EVEN USE STANDING WAVE CURRENT PHASE TO MEASURE THE PHASE SHIFT THROUGH A WIRE, much less through a coil. Given that standing wave current phase cannot be used to measure the delay through a wire, coil, or anything else, it follows that nobody has provided any valid measurements for the delay through a coil. >>A very similar thing happens with a 75m mobile antenna. >>The base loading coil provides tens of degrees of phase >>shift. > > How do you know that? The stub involves two different Z0's. The 75m mobile antenna involves two different Z0's, one for the coil, the other for the stinger. It's the same principles using the same equations. The phase shift at the impedance discontinuity depends upon the ratio of those two Z0's. The higher the ratio, the greater the phase shift. The ratio of 450 to 50 is obviously 9:1. A rough estimate of the Z0 of the coil is around 2400 ohms and a rough estimate of the Z0 of the stinger is around 400 ohms. That makes the Z0 ratios roughly 6:1. > I'm happy to see you no longer agree with the misplaced notion the > coil replaces missing electrical degrees, but puzzled why you resist > understanding the mechanism that allows the phase shift to change with > coil design. Speaking of what we both believed two years ago: I'm happy to see you no longer agree with the misplaced notion that the coil has equal current magnitudes and phases at each end, but puzzled why you resist understanding the low velocity factor associated with helical loading coils. The velocity factor of 75m bugcatcher loading coils is typically less than 0.1 From the Dr. Corum paper, we have an equation for velocity factor for coils passing a litmus test. A 75m bugcatcher coil passes that litmus test with flying colors. The resulting VF is in the ballpark of 0.04 which is in the ballpark of Reg's VF calculations which is in the ballpark of Richard Harrison's calculations. Your VF of 1.0 along the length of the coil is the one that is completely out of the ballpark. Take your 100uH coil and measure its self-resonant frequency directly over a large metal ground plane. Keeping everything, including frequency, the same, cut the coil in half. Add a stinger to the bottom half of the coil to bring the system back into resonance at the fixed frequency. We know the delay through the coil is roughly 45 degrees. We know the stinger is roughly 10 degrees. The impedance discontinuity at the coil to stinger junction is causing roughly 35 degrees of phase shift. That tells us that the Z0 ratio of the coil to stinger is about 6:1. I have been through the above exercise using EZNEC. -- 73, Cecil http://www.qsl.net/w5dxp Article: 223920 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Missing Degrees in Mobile Antennas? References: <9vp252pqm2fues06g4bq2kq0r0s6mt1ed3@4ax.com> <44517fdb$0$1010$39cecf19@news.twtelecom.net> <445184bf$0$1018$39cecf19@news.twtelecom.net> <1146236524.933305.75290@j33g2000cwa.googlegroups.com> <1146320344.271655.25720@y43g2000cwc.googlegroups.com> <8HL4g.77473$dW3.15538@newssvr21.news.prodigy.com> <1146329245.590217.72630@g10g2000cwb.googlegroups.com> Message-ID: Date: Sat, 29 Apr 2006 20:04:26 GMT w8ji@akorn.net wrote: > I'm saying that in an antenna of fixed length with a fixed coil > location on a given frequency, I can change ONLY the coil design, still > maintain resonance, and have phase delay of current change > significantly. So can I - so what? It's the same thing as changing the Z0 of one of the pieces of feedline in my two-Z0 stub example. No coil is required, indicating once again that your misconception involves standing waves, not coils. IMO, you are never going to understand this topic until you take time out to understand standing waves. > What is it you think > determines current phase shift at each end and current taper? I explained that at the start of the argument two years ago and it has been posted on my web page ever since then. http://www.qsl.net/w5dxp/current.htm Scroll down to: "Why the Net Current is not Constant Through a Loading Coil" > My example works in every case. No it doesn't. Your own current measurements prove that the current is *NOT* equal at both ends of a coil (and your phase measurements were invalid). Only one special case toroid showed the currents at the ends of the coil to be equal. All the other cases proved that the currents are *NOT* equal. As Gene Fuller said, the standing wave current phase information is contained in the magnitude. With a current of 2.0 amps at one end of the coil and a current of 1.414 amps at the other end of the coil, it exactly matches the example on my web page. One of your measurements was very close to 1 amp at one end and 0.7 amps at the other end. It fits perfectly. -- 73, Cecil http://www.qsl.net/w5dxp Article: 223921 of rec.radio.amateur.antenna From: "Dr.Death" Subject: Re: blame the posters not arrl Date: Sat, 29 Apr 2006 15:07:19 -0500 Message-ID: <1257hrlls8jm694@corp.supernews.com> References: <22se42d1ndkmbrj99p6675l6k2t16rplk4@4ax.com> <1146238178.410103.29330@y43g2000cwc.googlegroups.com> <1146271643.734737.155940@j73g2000cwa.googlegroups.com> <3lm5521h52e4jgalekjqq6g64e3i59u1mm@4ax.com> <1146333073.590407.297500@i39g2000cwa.googlegroups.com> "Fred" wrote in message news:cff752ptrbujv3st3o1r30ececm1f3oku4@4ax.com... > On 29 Apr 2006 10:51:13 -0700, "an_old_friend" > wrote: > >> >>Fred wrote: >>> On 28 Apr 2006 17:47:23 -0700, "an_old_friend" >>> wrote: >>> >>> > >>> >Fred wrote: >>> >> On 28 Apr 2006 08:29:38 -0700, "an old freind" >>> >> wrote: >>> >> >>> >> > >>> > >>> >> >> You said a mouthful. Oh and I agree with you. It just aint >>> >> >> natural! >>> >> >funny it occours outside of man and outside the primates in nature >>> >> >all >>> >> >the time >>> >> >>> >> So you are as stupid as a monkey or a dog? >>> > >>> >no you point? >>> > >>> >it looks like you are here to push your religous agenda and nothing to >>> >with radio >>> >>> If you were smart enough to read you would find out that I do not >>> believe in DOG. >>I never stated you did >>> I am just picking on you for being a militant pro-gay >>> that is trolling Usenet groups looking for acceptance of his sick >>> lifestyle. >> >>hardly you don't know what miliatant is >> >>you are psuhing you milltant religionous agenda where it desn't belong. >>you have the right to do that, as I have the right to post what I see >>fit >>your problem is that you can't face the fact I have the same rights as >>you do >> >>you want an end to defense of My Bisexaulity it can be had easiily >> >>you mustb( and the rest must refrain from atacking ti and refrain from >>using the cry or "faggot" as an arguement in the NG >> >>it is that simple but the likes of you have proven you can't do it > > How many times do I have to tell you that I am an atheist? You can > support and defend your faggotry all you want, but this is not the > forum for that sick shit. You have no right to harass people in > rec.radio.cb or any other newsgroup so suck on that you stupid turd > pusher. And to this day he has yet to make an on topic post. I'll bet he was given the answers while taking his ham test and still failed the first three times. Makes me wonder if he even has radio equipment. Article: 223922 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Velocity Factor and resonant frequency References: <12560ajs2oc286f@corp.supernews.com> <10935-44539EC6-55@storefull-3258.bay.webtv.net> <1146334972.592832.210040@v46g2000cwv.googlegroups.com> Message-ID: <6SP4g.18530$4L1.16553@newssvr11.news.prodigy.com> Date: Sat, 29 Apr 2006 20:18:10 GMT n3ox.dan@gmail.com wrote: > I think equation 28 can be solved in Matlab or Mathematica or something > else. I haven't quite figured out if Figure 1 uses approximations or > if it is numerical solutions of equation 28. If it's the latter, you > can just use the figure. Since Fig. 1 occurs after equation (32), I assumed it was for equation (32). The three variables in equation (32) are coil pitch, coil diameter, and wavelength. Those are essentially the same variables plotted in Fig. 1 with the diameter per wavelength ratio and the turns per wavelength ratio. Dr. Corum says that for coils passing the litmus equation test, the error is less than 10% which is perfectly acceptable for this discussion where W8JI's VF seems to be off by about 5000%. :-) -- 73, Cecil http://www.qsl.net/w5dxp Article: 223923 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: J_Pole Trials and Tribulations References: <1146008591.641742.237030@y43g2000cwc.googlegroups.com> <4tjt42lg6k5ustfmiljfkpiqdle084d0iq@4ax.com> <96N4g.77517$dW3.54166@newssvr21.news.prodigy.com> Message-ID: Date: Sat, 29 Apr 2006 20:21:29 GMT Allisonnospam@nouce.bellatlantic.net wrote: > I happen to like them as they can be made from common materials with > excellent ruggedness. A 1/4WL ground plane takes one SO-239 and five pieces of 19 inch copper wire (or stingers). :-) -- 73, Cecil http://www.qsl.net/w5dxp Article: 223924 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: J_Pole Trials and Tribulations References: <1146008591.641742.237030@y43g2000cwc.googlegroups.com> <4tjt42lg6k5ustfmiljfkpiqdle084d0iq@4ax.com> <96N4g.77517$dW3.54166@newssvr21.news.prodigy.com> <1257fp394gu7t3d@corp.supernews.com> Message-ID: Date: Sat, 29 Apr 2006 20:25:23 GMT Roy Lewallen wrote: > What's the mechanism which gives this half wave antenna 2.4 dB gain over > a half wave dipole? A J-Pole over ground obviously has gain over a half wave dipole in free space? :-) -- 73, Cecil http://www.qsl.net/w5dxp Article: 223925 of rec.radio.amateur.antenna From: Allisonnospam@nouce.bellatlantic.net Subject: Re: J_Pole Trials and Tribulations Message-ID: References: <1146008591.641742.237030@y43g2000cwc.googlegroups.com> <4tjt42lg6k5ustfmiljfkpiqdle084d0iq@4ax.com> <96N4g.77517$dW3.54166@newssvr21.news.prodigy.com> <1257fp394gu7t3d@corp.supernews.com> Date: Sat, 29 Apr 2006 20:32:08 GMT On Sat, 29 Apr 2006 12:31:44 -0700, Roy Lewallen wrote: >Allisonnospam@nouce.bellatlantic.net wrote: >> I happen to like them as they can be made from common materials with >> excellent ruggedness. As to the other claims of fantastic gain and >> all, it's bogus. It's a vertical halfwave endfed and the gain is >> 2.4ish DB over a dipole and that's all. If executed correctly it >> will be better than a 1/4wl groundplane but not by any fanstastic >> amount. For many applications that is a "good enough" antenna. >> >> Allison > >What's the mechanism which gives this half wave antenna 2.4 dB gain over >a half wave dipole? > >Modeling shows the gain to be the same as a dipole, if you can manage to >keep the current on the outside of the feedline to a small value. If you >can't, the gain in the horizontal direction typically becomes less than >a dipole. > >Roy Lewallen, W7EL Verticle polarization has less power headed toward space (up for a H-dipole) and still benefits from ground effects. The model for free space nets the same gain as dipole. The problem with free space is my backyard has dirt in it. However for free space groundplane compared to free space verticle halfwave there is gain. Better radiation angle as well. Allison Article: 223926 of rec.radio.amateur.antenna From: Allisonnospam@nouce.bellatlantic.net Subject: Re: J_Pole Trials and Tribulations Message-ID: References: <1146008591.641742.237030@y43g2000cwc.googlegroups.com> <4tjt42lg6k5ustfmiljfkpiqdle084d0iq@4ax.com> <96N4g.77517$dW3.54166@newssvr21.news.prodigy.com> Date: Sat, 29 Apr 2006 20:41:20 GMT On Sat, 29 Apr 2006 20:21:29 GMT, Cecil Moore wrote: >Allisonnospam@nouce.bellatlantic.net wrote: > >> I happen to like them as they can be made from common materials with >> excellent ruggedness. > >A 1/4WL ground plane takes one SO-239 and five pieces of >19 inch copper wire (or stingers). :-) Now drive over one with a Chevy Pickup, the Jpole survived that at field day one year. Yes, if you used similar material (1/2" copper pipe) likely a ground plane might have survived but it would be far from simple to construct using "Plumber delight" methods. I have no dislike for 1/4 WL antennas, I use them too. Allison Article: 223927 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: J_Pole Trials and Tribulations References: <1146008591.641742.237030@y43g2000cwc.googlegroups.com> <4tjt42lg6k5ustfmiljfkpiqdle084d0iq@4ax.com> <96N4g.77517$dW3.54166@newssvr21.news.prodigy.com> Message-ID: Date: Sat, 29 Apr 2006 21:07:25 GMT Allisonnospam@nouce.bellatlantic.net wrote: > Cecil Moore wrote: >>A 1/4WL ground plane takes one SO-239 and five pieces of >>19 inch copper wire (or stingers). :-) > > Now drive over one with a Chevy Pickup, the Jpole survived that > at field day one year. Well, I just did that with a GMC pickup (hope that counts). Nothing broke. I just straightened out the wires and it still works just fine. If, Heaven forbid, a wire broke, it would only take a butt connector and 20 seconds to repair it. -- 73, Cecil http://www.qsl.net/w5dxp Article: 223928 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Missing Degrees in Mobile Antennas? References: <9vp252pqm2fues06g4bq2kq0r0s6mt1ed3@4ax.com> <44517fdb$0$1010$39cecf19@news.twtelecom.net> <445184bf$0$1018$39cecf19@news.twtelecom.net> <1146236524.933305.75290@j33g2000cwa.googlegroups.com> <1146320344.271655.25720@y43g2000cwc.googlegroups.com> <8HL4g.77473$dW3.15538@newssvr21.news.prodigy.com> <1146328640.915773.282060@i40g2000cwc.googlegroups.com> <1146345231.139348.4050@v46g2000cwv.googlegroups.com> Message-ID: Date: Sat, 29 Apr 2006 21:38:37 GMT w8ji@akorn.net wrote: > Earlier we both agreed the current we measure with a magnetic probe, > which is the most common and widely accepted measurement device, is the > actual current that causes radiation, heating, and the magnetic > induction field. It is the current that heats the element and moves a > thermocouple meter, it is the current that cause I^2R heating, and the > current that moves past one point in the system if we stopped and > counted charges, or if we calculated current based on drift velocity of > charge carriers. It is the current that has the equation: Itot = Io*cos(kx)*cos(wt) Until you take time out to understand the implications of that equation, you will *never* understand what I am talking about. That current cannot be used to measure delay. Yet, that is exactly what you and W7EL did and, in your ignorance, reported as valid measurements of delay through a coil. If you had a clue to what you are saying, you would feel ignorant in the extreme. > So what current is it you are measuring? Charges cannot flow two > directions at the same time at the same point in a system. There cannot > be drift velocity in two dorections at the same time. Just as two water waves can flow in opposite directions using the same water molecules, two EM waves can flow in opposite directions using the same electrons. > Are you talking about a pulse of current and the return echo? You know that I am talking about the distributed network model, a superset of the lumped circuit model. Instead of rehashing it here, please refer to my magazine article at: http://www.qsl.net/w5dxp/energy.htm and tell me what it is about that article that you don't understand. >>2. There is no appreciable standing wave current phase shift from >>feedpoint to the tip of the stinger in a 75m mobile bugcatcher >>antenna. To be consistent, don't you have to argue that the >>75m mobile bugcatcher antenna is zero degrees long? > It is however long it is. Exactly the same argument holds for a coil. Think about it. You cannot deny the validity of standing wave current phase measurements through a stinger and then turn around and deny that same argument when it applies to a coil. If W7EL's phase measurements were invalid for a stinger, then they were equally invalid for a coil. > I never said 1.0, as a matter of fact the coil I measured had a vF > (when compared to physical length) of about .5 Sorry, that's still about 1000% too high, still completely out of the ballpark. What I suspect is that you measured zero delay through the coil and reported 3 nS because you knew zero was obviously wrong. -- 73, Cecil http://www.qsl.net/w5dxp Article: 223929 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Missing Degrees in Mobile Antennas? References: <9vp252pqm2fues06g4bq2kq0r0s6mt1ed3@4ax.com> <44517fdb$0$1010$39cecf19@news.twtelecom.net> <445184bf$0$1018$39cecf19@news.twtelecom.net> <1146236524.933305.75290@j33g2000cwa.googlegroups.com> <1146320344.271655.25720@y43g2000cwc.googlegroups.com> <8HL4g.77473$dW3.15538@newssvr21.news.prodigy.com> <1146329245.590217.72630@g10g2000cwb.googlegroups.com> <1146345440.066253.316730@y43g2000cwc.googlegroups.com> Message-ID: Date: Sat, 29 Apr 2006 21:52:26 GMT w8ji@akorn.net wrote: > So you don't want to say, or can't say in a few words? I know one of your tactics used to "win" an argument is to wear the opponent down to a nub where it is not worth the effort to continue even when he is right and you are wrong. I'm not going to play your silly game. All the information is there on my web page at: http://www.qsl.net/w5dxp/current.htm -- 73, Cecil http://www.qsl.net/w5dxp Article: 223930 of rec.radio.amateur.antenna From: "Brian Murrey" Subject: Mobile Antenna Question.. Message-ID: Date: Sat, 29 Apr 2006 21:59:19 GMT I have a 2004 Ford Tarus SES and I was thinking about putting a mobie HF antenna on it so I can play radio while driving from city to city doing my job. I have never had a mobile HF rig so I have some questions. First...is there a website, newsgroup, or some other resource that might have some HF antenna mounting info about my particular car? I'm thinking about using a hamstick or a Workman Mobile from Hamstop on eBay. I guess the big gnarley triple mag mount would work, but I was also thinking about a license plate mounting kit....any suggestions? How tall are these types of antennas for 40m, and 20m? My rig is a KX1 and it has 20, 30, and 40 meter capability. Thanks 73 de KB9BVN -- ========================================= Radio Amateurs - Fill your junk box, from my junkbox! http://www.hamradparts.com 73 de KB9BVN ========================================= Article: 223931 of rec.radio.amateur.antenna From: Buck Subject: Re: TT-247 and 102 whip for mobile antenna ? Message-ID: <2cq752thr268ojtdknkqe9vae80mq2lk4a@4ax.com> References: <6na4521tmlo4ipifhhgo0u5dvt43t3l25c@4ax.com> Date: Sat, 29 Apr 2006 18:34:54 -0400 On Sat, 29 Apr 2006 14:19:33 GMT, Cecil Moore wrote: >Buck wrote: >> I have used a Hustler on 75 before. I was definitely >> a weak signal station. I can only imagine that a tuned whip would >> generate similar results, or more likely, poorer results. > >Following are the summarized normalized combined results >of three 75m mobile antenna shootouts held in California >during the 1980's. > >0 dB - (Reference) Bugcatcher or Screwdriver with large top hat > >-2 dB - Bugcatcher or Screwdriver with no top hat > >-5 dB - 8.5' whip with bugcatcher base loading coil > >-6 dB - Bugcatcher with Stainless Steel Loading Coil > >-8 dB - Hustler High Power system > >-9 dB - Outbacker > >-12 dB - Hamstick > >-12 dB - 11.5' whip with SGC-230 autotuner > >-14 dB - 8.5' whip with SGC-230 autotuner (estimated, not measured) Thank you, that is good to see. -- 73 for now Buck N4PGW Article: 223932 of rec.radio.amateur.antenna From: Buck Subject: Re: TT-247 and 102 whip for mobile antenna ? Message-ID: References: <6na4521tmlo4ipifhhgo0u5dvt43t3l25c@4ax.com> <055752d74trn10kgf3m77vi6o1hl484atj@4ax.com> Date: Sat, 29 Apr 2006 18:37:46 -0400 SNIP >This is another instance of not believing everything - but it at least >this time it offers a nugget of truth. This is the spin of the wheel >of chance I mentioned above. Don't fret so much and simply try it in >the driveway. Open the tuner, fire up the rig and tune for lowest >SWR. Let go of the key and touch components to see how hot it's >gotten. You don't need infra-red analysis and toolkit of thermocouple >probes to obtain a good understanding of the situation. Repeat on all >bands. > >73's >Richard Clark, KB7QHC Thanks, After reading all this, I will be going to get the antenna. I have a mount on side of the van. i will re-wire it so it goes to an SO-239 connector so I can mount the tuner next to the antenna for the test. if all is well, I will get a hole kit and set it up on the roof. I like the bug-catcher idea, but I don't have the parts :(. Thanks, again, Buck -- 73 for now Buck N4PGW Article: 223933 of rec.radio.amateur.antenna From: Buck Subject: Re: TT-247 and 102 whip for mobile antenna ? Message-ID: References: <6na4521tmlo4ipifhhgo0u5dvt43t3l25c@4ax.com> <92m552p0gku2map37b381iomes9r87b58u@4ax.com> <6OL4g.10069$Lm5.1814@newssvr12.news.prodigy.com> Date: Sat, 29 Apr 2006 18:39:42 -0400 On Sat, 29 Apr 2006 15:40:50 GMT, Bob wrote: >Used various SGC tuners and Icom AH-4. Also tried both of SGCs dual >loaded whips with varying results. The longer two piece unit worked >surprisingly well 80-10m years ago when conditions were better, even had >some fantastic 160m mobile contacts with it. The single 7ft version >lacks on 40 and especially 80m compared to the two piece whip but >compared to an unloaded 102” CB whip, it makes the CB whip look like a >dummy load on 40m and below. This is all with an SGC-230 feeding them. >Bob > How long is the two piece whip? -- 73 for now Buck N4PGW Article: 223934 of rec.radio.amateur.antenna From: "Kevin & Natalia" Subject: Re: Mobile Antenna Question.. Date: Sun, 30 Apr 2006 10:41:37 +1200 Message-ID: <1146350351.336138@ftpsrv1> References: Brian, Also check out the Outbacker mobile antenna, I use one of these on my Toyota Landcruiser, and works a dream. Whatever antenna you decide to get make sure that it is in free space as much as you can, this helps cut down car reflection, which is cases by metal interaction. I made a robust mount on the spare-wheel frame that hangs off the back of the truck, and this made the job easier. As for mag-mounts, take into full account the speed you may do, and the wind resistance the new antenna will produce. Have heard of operators using a mag-mount for even a smaller antenna, only to see in the mirror, it hanging or laying over the back. Most mobile antennas are about 1.4mtrs up, my outbacker is approx 1.6mtrs >from the base to tip, and this is another 1.2mtrs off the ground. I can send you a photo if you wish, and helps explain my setup? All the best, willing to help if you have any further questions. Kevin, ZL1KFM. "Brian Murrey" wrote in message news:XkR4g.10940$sq5.5363@newsread2.news.atl.earthlink.net... >I have a 2004 Ford Tarus SES and I was thinking about putting a mobie HF > antenna on it so I can play radio while driving from city to city doing my > job. > > I have never had a mobile HF rig so I have some questions. > > First...is there a website, newsgroup, or some other resource that might > have some HF antenna mounting info about my particular car? > > I'm thinking about using a hamstick or a Workman Mobile from Hamstop on > eBay. I guess the big gnarley triple mag mount would work, but I was also > thinking about a license plate mounting kit....any suggestions? > > How tall are these types of antennas for 40m, and 20m? My rig is a KX1 > and > it has 20, 30, and 40 meter capability. > > Thanks > > 73 de KB9BVN > > > -- > ========================================= > Radio Amateurs - Fill your junk box, from my junkbox! > http://www.hamradparts.com > 73 de KB9BVN > ========================================= > > > Article: 223935 of rec.radio.amateur.antenna From: "Kevin & Natalia" Subject: Wanted - NZ Huttons HF Antenna Mobile Base Required. Date: Sun, 30 Apr 2006 10:44:20 +1200 Message-ID: <1146350483.890752@ftpsrv1> Hi All, I am in the need of a NZ made Huttons HF antenna mobile base, preferably the tilt-over type. My last one was lost when my car was stolen, and the mount still attached. If anyone has one that I might get/purchase, could you please contact me directly. Regards Kevin, ZL1KFM Article: 223936 of rec.radio.amateur.antenna From: Roy Lewallen Subject: Re: J_Pole Trials and Tribulations Date: Sat, 29 Apr 2006 15:45:29 -0700 Message-ID: <1257r4cqp26dsfa@corp.supernews.com> References: <1146008591.641742.237030@y43g2000cwc.googlegroups.com> <4tjt42lg6k5ustfmiljfkpiqdle084d0iq@4ax.com> <96N4g.77517$dW3.54166@newssvr21.news.prodigy.com> <1257fp394gu7t3d@corp.supernews.com> Allisonnospam@nouce.bellatlantic.net wrote: > > Verticle polarization has less power headed toward space (up for a > H-dipole) and still benefits from ground effects. The model for free > space nets the same gain as dipole. The problem with free space is > my backyard has dirt in it. It appears you're comparing a half wave horizontal dipole with a (half wave) J pole. Ground does have a major impact on the performance of the antennas, but the reflection results in loss of a lot of signal power if the wave is at a low angle and vertically polarized. Horizontally polarized waves, in contrast, reflect with very little loss at low angles. I haven't tried modeling it, but would guess that in a typical line-of-sight path where there can be one ground reflection in addition to the direct path, the signal would go through fades and reinforcements as you varied the antenna height. Because of the lower loss of horizontally polarized reflections, the fades would be deeper and the reinforcements stronger with horizontal polarization. On the average, the horizontal would be better (that is, the average signal for all heights would be stronger) because no significant loss is incurred in the reflection. But getting a decent signal would be much more of a gamble. Those looking at modeling results from EZNEC or similar programs should realize that the far field analysis isn't a good simulation of this situation. Probably the best way to model it would be to model two antennas, one at each location, over ground. Put a source in one antenna (the transmitting antenna) and a conjugately matched load at the feedpoint of the other (the receiving antenna). Then look at the power delivered to the load for various receiving antennas. There's a practical limit to how far apart the antennas can be before numerical limitations are reached, but with double precision calculations they can be quite a distance apart. The conventional J pole with half wavelength radiator has the same gain as a vertical half wave dipole, again assuming you can keep the current on the outside of the feedline to a low value for both antennas. > > However for free space groundplane compared to free space verticle > halfwave there is gain. Better radiation angle as well. A quarter wavelength vertical ground plane antenna has the same gain and pattern as a half wavelength vertical dipole, and the same as a J pole (if you can keep the current on the outside of the J pole feedline to a reasonably small value). This is true whether in free space or over ground, and it can be demonstrated by theory, measurement, and modeling. Roy Lewallen, W7EL Article: 223937 of rec.radio.amateur.antenna From: Buck Subject: Re: Mobile Antenna Question.. Message-ID: References: Date: Sat, 29 Apr 2006 18:47:41 -0400 On Sat, 29 Apr 2006 21:59:19 GMT, "Brian Murrey" wrote: >I have a 2004 Ford Tarus SES and I was thinking about putting a mobie HF >antenna on it so I can play radio while driving from city to city doing my >job. > >I have never had a mobile HF rig so I have some questions. > >First...is there a website, newsgroup, or some other resource that might >have some HF antenna mounting info about my particular car? > >I'm thinking about using a hamstick or a Workman Mobile from Hamstop on >eBay. I guess the big gnarley triple mag mount would work, but I was also >thinking about a license plate mounting kit....any suggestions? > >How tall are these types of antennas for 40m, and 20m? My rig is a KX1 and >it has 20, 30, and 40 meter capability. > >Thanks > >73 de KB9BVN I have been using a quad-magnet mount with an Antenna Speciallists antenna (resembles the ham stick) very successfully. The antenna has been mounted on the roof where I used 75, 40 and 20 meters. However, being less careful at the time, I lost the 75 meter antenna when I hit a low bridge at 35 MPH. (something to think about.) The antennas worked very well, but I got tired of changing them. I added a mount from under the bumper of my car and was able to use 20 meters there, but the low bands didn't drop SWR below 2:1 so I only used them on the roof. I have made numerous DX and other contacts >from the roof mounted antennas including an italian station on 40 meters. Once I got two antennas working, 20 on the bumper and 40 on the roof, I was happy for a while. Now I want more than two bands and I would like to cover a wider bandwidth, so I have another thread discussing my latest attempt at a mobile antenna idea. Good luck, and let us know. Buck N4PGW -- 73 for now Buck N4PGW Article: 223938 of rec.radio.amateur.antenna From: Bob Subject: Re: TT-247 and 102 whip for mobile antenna ? References: <6na4521tmlo4ipifhhgo0u5dvt43t3l25c@4ax.com> <92m552p0gku2map37b381iomes9r87b58u@4ax.com> <6OL4g.10069$Lm5.1814@newssvr12.news.prodigy.com> Message-ID: Date: Sat, 29 Apr 2006 23:49:31 GMT About 8 or 8 1/2ft. Bob Buck wrote: > On Sat, 29 Apr 2006 15:40:50 GMT, Bob wrote: > >> Used various SGC tuners and Icom AH-4. Also tried both of SGCs dual >> loaded whips with varying results. The longer two piece unit worked >> surprisingly well 80-10m years ago when conditions were better, even had >> some fantastic 160m mobile contacts with it. The single 7ft version >> lacks on 40 and especially 80m compared to the two piece whip but >> compared to an unloaded 102” CB whip, it makes the CB whip look like a >> dummy load on 40m and below. This is all with an SGC-230 feeding them. >> Bob >> > How long is the two piece whip? Article: 223939 of rec.radio.amateur.antenna From: Bill Turner Subject: Re: Mobile Antenna Question.. Date: Sat, 29 Apr 2006 18:10:57 -0700 Message-ID: <7k2852dl08otp53phggp9nbi9rkg92q0cg@4ax.com> References: ORIGINAL MESSAGE: On Sat, 29 Apr 2006 21:59:19 GMT, "Brian Murrey" wrote: >I have a 2004 Ford Tarus SES and I was thinking about putting a mobie HF >antenna on it so I can play radio while driving from city to city doing my >job. *********** REPLY SEPARATOR *********** Fords of any kind are notorious for noise, but if you are determined to go through with it: 1. A triple mag mount will work fine with HamStick antennas. I use an IronHorse one and I guarantee that will not come off in the wind. I can't hardly get it off with a pry bar. 2. Hamsticks are excellent on 20-10 meters and pretty good on 40. 3. Not so good on 80. 4. I don't know what an "SES" is, but if it's shaped like a regular car (not an SUV) put the triple mag mount on the trunk. No need to put it on the roof unless you like people staring at you. 5. Run a separate ground wire from the base of the mag mount to the chassis of the car. Don't rely on the capacitance of the mag mount, especially on the lower freqs. On ten meters and possibly 15 you might get away with it, but on 20 and lower freqs your SWR will probably be high. Use some forethought and make the ground wire as short as possible, no more than about six or maybe eight inches. 6. Next time get a Chrysler product. :-) Also, there is a mobileham forum on www.eham.net which may be a source of more info oriented specifically toward mobiling. Have fun! Bill, W6WRT Article: 223940 of rec.radio.amateur.antenna From: "Brian Murrey" References: Subject: Re: Mobile Antenna Question.. Message-ID: Date: Sun, 30 Apr 2006 02:24:27 GMT Thanks for all the info guys. I think I am going with a 20m and a 40m Hamstick type of antenna. I will most likely be mounting it to the Taurus (which is a car and not a SUV) with one of those license plate mounting kits. I am making the mounting kit in the metal shop next week. It will be stainless steel and about twice as thick as the one Lakeview sells. I can get a few very good grounds with the license plate mount. I will then run some 10 ga stranded wires to the battery and fuse both sides near the battery. I will make a connector cable for my KX1 so it mates up OK. The KX1 is only 4w out so I could probably run it off the cigarette lighter...which I might do anyway. I think the cig lighter is rated at 10A so should be over kill. I am also making a mount for my 2004 Durango so I can move the antenna and rig between vehicles. I have ordered a few of the quick disconnect joints for the mount. I will probably use RG8X for the antenna feed line. The KX1 has a built in antenna tuner. 73 de KB9BVN -- ========================================= Radio Amateurs - Fill your junk box, from my junkbox! http://www.hamradparts.com 73 de KB9BVN ========================================= Article: 223941 of rec.radio.amateur.antenna From: Buck Subject: Re: TT-247 and 102 whip for mobile antenna ? Message-ID: References: <6na4521tmlo4ipifhhgo0u5dvt43t3l25c@4ax.com> <055752d74trn10kgf3m77vi6o1hl484atj@4ax.com> Date: Sat, 29 Apr 2006 23:47:15 -0400 On Sat, 29 Apr 2006 16:32:50 -0700, Richard Clark wrote: >On Sat, 29 Apr 2006 18:37:46 -0400, Buck wrote: > >>I like the bug-catcher idea, but I don't have the parts :(. > >You don't have any WIRE? This is preposterous. > >You split the vertical rise with an insulator and wind WIRE to fill >the gap. End of story. Your job is to make it mechanically sound at >70MPH and thumb your nose at what may be called Q here. > >You want a bigger coil? Have dreams of that Q that marks status here? > >Wrap a coffee can with several many wraps of paper so it clears all >seams and beads. Wrap turns of wire around the can/paper. Add epoxy >in nice neat lines along six lengths around the circumference (use >modeling or florist clay to build dams). Wait a couple of days for it >to cure. Take out the can and paper. Clean off the clay. Paint it >red, white, and blue! > >What can 40 or 50 feet of wire, clay, three colors of paint, and an >ounce of epoxy cost? $5? > >73's >Richard Clark, KB7QHC LOL I haven't looked into that yet. I will. Thanks. -- 73 for now Buck N4PGW Article: 223942 of rec.radio.amateur.antenna From: Buck Subject: Re: TT-247 and 102 whip for mobile antenna ? Message-ID: References: <6na4521tmlo4ipifhhgo0u5dvt43t3l25c@4ax.com> <92m552p0gku2map37b381iomes9r87b58u@4ax.com> <6OL4g.10069$Lm5.1814@newssvr12.news.prodigy.com> Date: Sat, 29 Apr 2006 23:49:20 -0400 On Sat, 29 Apr 2006 23:49:31 GMT, Bob wrote: >About 8 or 8 1/2ft. >Bob > >Buck wrote: >> On Sat, 29 Apr 2006 15:40:50 GMT, Bob wrote: >> >>> Used various SGC tuners and Icom AH-4. Also tried both of SGCs dual >>> loaded whips with varying results. The longer two piece unit worked >>> surprisingly well 80-10m years ago when conditions were better, even had >>> some fantastic 160m mobile contacts with it. The single 7ft version >>> lacks on 40 and especially 80m compared to the two piece whip but >>> compared to an unloaded 102” CB whip, it makes the CB whip look like a >>> dummy load on 40m and below. This is all with an SGC-230 feeding them. >>> Bob >>> >> How long is the two piece whip? Is there more to the two-piece than just two pieces? Is it a loaded fiberglass whip with a stinger, or two solid pieces of wire making up one long stinger. If so, the cb whip is longer, if you have a loaded section, the loaded section is longer. -- 73 for now Buck N4PGW Article: 223943 of rec.radio.amateur.antenna From: "Tom Donaly" Subject: Re: A little more on missing degrees References: Message-ID: Date: Sun, 30 Apr 2006 03:59:46 GMT Reg Edwards wrote: > I havn't much idea on what the present argument is all about. And I > have no wish to take sides. > > But - > > If Line-1 has impedance Zo1 and is a fractional wavelength L1 long, > > and Line-2 has impedance Zo2 and is a fractional wavelength L2 long, > > then when both lines are connected together and are brought into > so-called 1/4-wave resonance by pruning the length of one of the > lines, it is IMPOSSIBLE for L1 + L2 to equal 1/4-wavelength or 90 > degrees. > > There are ALWAYS some degrees "missing" - depending on the ratio > Zo1/Zo2. > > Except only when Zo1 = Zo2 will L1 + L2 total 90 degrees. > > Can be proved mathematically without invoking standing or reflected > waves. You just have to believe in mathematics. > > Line-1, of course, is a loading coil and Line-2 is a whip. > > I hope this settles an argument. > > For a demonstration download program TWOLINES from website below. > ---- > ........................................................... > Regards from Reg, G4FGQ > For Free Radio Design Software go to > http://www.btinternet.com/~g4fgq.regp > ........................................................... > > And what is line three and line four? 73, Tom Donaly, KA6RUH Article: 223944 of rec.radio.amateur.antenna From: Bob Subject: Re: TT-247 and 102 whip for mobile antenna ? References: <6na4521tmlo4ipifhhgo0u5dvt43t3l25c@4ax.com> <92m552p0gku2map37b381iomes9r87b58u@4ax.com> <6OL4g.10069$Lm5.1814@newssvr12.news.prodigy.com> Message-ID: Date: Sun, 30 Apr 2006 04:55:45 GMT I believe the SGC whip is continuously loaded with a tapered pitch over a large diameter fiberglass core and also has a straight internal shorter section for higher freqs. No top stinger, just big, thick, ugly black heatshrink coated. I think it resonates around 13 and 22MHz. Look up an SG-303 in Google. Bob Buck wrote: >>> How long is the two piece whip? > Is there more to the two-piece than just two pieces? Is it a loaded > fiberglass whip with a stinger, or two solid pieces of wire making up > one long stinger. If so, the cb whip is longer, if you have a loaded > section, the loaded section is longer. > Article: 223945 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: A little more on missing degrees References: Message-ID: Date: Sun, 30 Apr 2006 05:05:35 GMT Reg Edwards wrote: > If Line-1 has impedance Zo1 and is a fractional wavelength L1 long, > > and Line-2 has impedance Zo2 and is a fractional wavelength L2 long, > > then when both lines are connected together and are brought into > so-called 1/4-wave resonance by pruning the length of one of the > lines, it is IMPOSSIBLE for L1 + L2 to equal 1/4-wavelength or 90 > degrees. If we have three sections and Z02 > Z01, ---Z01---+---Z02---+---Z01--- the first impedance discontinuity causes a phase shift in the *opposite* direction from the second impedance discontinuity. That's why moving a loading coil from a base-loaded position to a center-loaded position requires more degrees of coil. W8JI has been trying to make a big deal out of that fact but it is just simple physics. -- 73, Cecil http://www.qsl.net/w5dxp Article: 223946 of rec.radio.amateur.antenna Date: Sun, 30 Apr 2006 00:19:54 -0500 From: Tom Ring Subject: Re: Velocity Factor and resonant frequency References: <1146269331.884979.12810@j73g2000cwa.googlegroups.com> <17735-4452E640-132@storefull-3251.bay.webtv.net> <12560ajs2oc286f@corp.supernews.com> Message-ID: <445448fa$0$1018$39cecf19@news.twtelecom.net> Tom Donaly wrote: > Beware of academics who use phrases such as "anisotropically conducting > cylindrical boundary," "helically disposed surface waveguide," and > "voltage magnification by standing waves." These are just figures of > speech. Some academics - fractenna comes to mind - get so carried away > with their ideas, they'll try anything to justify them, including the > use of nounspeak and polysyllabic jargon. Real scientists and engineers > don't have to use such tactics to make a point. > 73, > Tom Donaly, KA6RUH Beware of academics who use "real physical based equations" as they may mislead you because they are based in reality. tom K0TAR Article: 223947 of rec.radio.amateur.antenna From: "Mr Fed UP" References: Subject: Re: May 1st 2006, Civil War Begins Message-ID: Date: Sun, 30 Apr 2006 02:11:36 -0500 This has nothing to do with AMATEUR. ANTENNA..... TAKE THIS JUNK SOME PLACE ELSE AND GO SCREW A HOT TOWER "stananger" < stananger@********.***> wrote in message news:EuCdncdjBYGsf8_ZRVn-hA@hawaiiantel.net... > May 1st 2006, Civil War Begins > > On May 1st 2006 The "Great American Boycott" also known as the "Day > without > immigrants" is scheduled to occur. Participant's stated goals are a > general > strike, No Work, No School, No Sales, and No Buying. These people want to > shut down individual cities, all across the nation, thereby impacting the > country as a whole. > Make no mistake about it, this is not just simple protesting, protesting > with the goal of causing financial harm is Economic Terrorism plain and > simple - and those people who participate are economic terrorists. > By shutting down certain cities, or even portions of cities, these > protestors will be : > Keeping children out of school, > Hampering the abilities of local law enforcement to enforce the law, > Hampering the abilities of first responders to respond to car accidents, > fires, people having heart attacks, and hampering their ability to > transport them to the hospital. > Hampering the abilities of local mass transit systems to operate properly. > Causing financial harm to local businesses iregardless of whether or not > those businesses have harmed them, resulting in a nationwide economic > impact. > Advocating the breaking of our laws by demanding, yes demanding, that > illegal immigrants be given amnesty. > > > ter·ror·ism -"The unlawful use or threatened use of force or violence by > a > person or an organized group against people or property with the intention > of intimidating or coercing societies or governments, often for > ideological > or political reasons." - American Heritage® Dictionary of the English > Language, Fourth Edition > How can you fight back? > Ensure that your children go to school, and stay there on this day. > Purposely go and buy products and services in those cities affected by the > protestors - gas up your car, go see a movie, go grocery shopping, buy a > little more than you would have any other day. Counter their 'protest' > with > a positive economic impact in those areas affected. > Perhaps you might also consider making a donation to those organizations > seeking to secure our borders on this day as well. Show these terrorists > that you can and will fight back! > While the current situation is one of mass irresponsible action, causing > financial harm across the nation, it will inevitably escalate into > violence > and deaths if these sorts of activities continue. > Does this constitute a civil war? Perhaps not yet, but its clearly heading > in that direction, this may just be the first battle. Article: 223948 of rec.radio.amateur.antenna From: "Guy" References: <22se42d1ndkmbrj99p6675l6k2t16rplk4@4ax.com> <1146238178.410103.29330@y43g2000cwc.googlegroups.com> <1146271643.734737.155940@j73g2000cwa.googlegroups.com> <3lm5521h52e4jgalekjqq6g64e3i59u1mm@4ax.com> <1146333073.590407.297500@i39g2000cwa.googlegroups.com> <1257hrlls8jm694@corp.supernews.com> <1146368310.284179.91600@j33g2000cwa.googlegroups.com> Subject: Re: blame the posters not arrl Message-ID: Date: Sun, 30 Apr 2006 06:06:52 -0500 "an_old_friend" wrote in message news:1146368310.284179.91600@j33g2000cwa.googlegroups.com... > > Terry Two Shoes wrote: >> "Dr.Death" wrote in message >> news:1257hrlls8jm694@corp.supernews.com... >> "Fred" wrote in message >> news:cff752ptrbujv3st3o1r30ececm1f3oku4@4ax.com... >> > On 29 Apr 2006 10:51:13 -0700, "an_old_friend" >> > wrote: > >> If passing a Ham test was predicated upon correct spelling, he'd be a >> washout. > > but spelling corect on the fly is not requirement noris punkchuation > spasing orany efert 2make it ezyon thu reedr > Article: 223949 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Velocity Factor and resonant frequency References: <12560ajs2oc286f@corp.supernews.com> <10935-44539EC6-55@storefull-3258.bay.webtv.net> <1146334972.592832.210040@v46g2000cwv.googlegroups.com> <7jU4g.77642$dW3.22733@newssvr21.news.prodigy.com> <1146380239.089435.216750@j33g2000cwa.googlegroups.com> Message-ID: <_X15g.18751$4L1.8107@newssvr11.news.prodigy.com> Date: Sun, 30 Apr 2006 12:20:10 GMT w8ji@akorn.net wrote: > TE, TM, or TEM a small loading coil cannot behave very much like a > transmission line. We are not discussing small coils, Tom. We are discussing big honking 75m bugcatcher coils. Why do you guys always retreat >from the real world into the area of "small" coils? > If you read the Corum paper carefully, you see he clearly states it is > an approximation or solution for a coil under the very special > condition of being self-resonant. False. He clearly states that the VF and Z0 were established at the self-resonant frequency and that those values hold as long as the coil pitch, coil diameter, and frequency remain unchanged. That's exactly what I have done using EZNEC models. > He is working on Tesla coils, not loading coils. The first words in the title are, "RF Coils, ...". Figure 2 looks just like a 75m bugcatcher system with a top hat. A 75m bugcatcher coil is a helical resonator that brings the antenna system into resonance. He has a litmus test for RF coils. If the coil dimensions pass the litmus test, then his VF and Z0 equations are known to be valid within 10%. A 75m bugcatcher coil passes that litmus test by a 100% margin. A self-resonant coil is 90 degrees long. Dr. Corum says the lumped circuit model doesn't work until the coil is trimmed down to 0.167 of that length. Seems you have proven that to be true. > Notice also how Cecil misquotes to make a point. The Vf I measured on > 80 meters for a large bug-catcher style coil was actually .5 compared > to spatial length, not 1.0 Sorry, my memory was faulty on that one but 0.5 is still 1000% different from the value predicted by Dr. Corum's VF equation and flies in the face of known technical facts about coils. > On the other hand Cecil has measured virtually nothing, Yuri has > measured nothing, ... Which is better, Tom. Valid science or invalid measurements? You still haven't answered my question as to why you don't just assert that a 1/4WL monopole is zero degrees long since there is zero degrees of phase shift in the standing wave current phase >from end to end in the antenna. Heck, you can even prove that a 1/2WL thin-wire dipole is zero degrees long using the same measurement techniques that you used on a coil. > ... and Harrison probably hasn't even owned a bug catcher > coil being a technician class license holder. Instead of belittling his ham license, how about you compare your technical degrees to "Harrison's"? -- 73, Cecil http://www.qsl.net/w5dxp Article: 223950 of rec.radio.amateur.antenna From: Buck Subject: Re: TT-247 and 102 whip for mobile antenna ? Message-ID: References: <6na4521tmlo4ipifhhgo0u5dvt43t3l25c@4ax.com> <92m552p0gku2map37b381iomes9r87b58u@4ax.com> <6OL4g.10069$Lm5.1814@newssvr12.news.prodigy.com> Date: Sun, 30 Apr 2006 08:39:45 -0400 Ok, That makes sense That gives me an idea. I wonder what stacking my 20 meter base on top of my 40 meter base would produce. I'll try that today. I did some testing, see my followup in this thread. Thanks Buck On Sun, 30 Apr 2006 04:55:45 GMT, Bob wrote: >I believe the SGC whip is continuously loaded with a tapered pitch over >a large diameter fiberglass core and also has a straight internal >shorter section for higher freqs. No top stinger, just big, thick, ugly >black heatshrink coated. I think it resonates around 13 and 22MHz. Look >up an SG-303 in Google. >Bob > > >Buck wrote: > >>>> How long is the two piece whip? >> Is there more to the two-piece than just two pieces? Is it a loaded >> fiberglass whip with a stinger, or two solid pieces of wire making up >> one long stinger. If so, the cb whip is longer, if you have a loaded >> section, the loaded section is longer. >> -- 73 for now Buck N4PGW Article: 223951 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Missing Degrees in Mobile Antennas? References: <9vp252pqm2fues06g4bq2kq0r0s6mt1ed3@4ax.com> <44517fdb$0$1010$39cecf19@news.twtelecom.net> <445184bf$0$1018$39cecf19@news.twtelecom.net> <1146236524.933305.75290@j33g2000cwa.googlegroups.com> <1146320344.271655.25720@y43g2000cwc.googlegroups.com> <8HL4g.77473$dW3.15538@newssvr21.news.prodigy.com> <1146328640.915773.282060@i40g2000cwc.googlegroups.com> <1146345231.139348.4050@v46g2000cwv.googlegroups.com> <1146381453.661999.41270@i40g2000cwc.googlegroups.com> Message-ID: Date: Sun, 30 Apr 2006 12:45:01 GMT w8ji@akorn.net wrote: > Sorry Cecil, I cannot get into my network analyzer and make it show a > delay on a printout that isn't actually there. I push the button, it > prints the data it takes. Yes, and you have previously said that any answer is better than no answer at all, presumably including answers obtained using invalid measurement techniques. If you take your network analyzer and measure the current phase shift from end to end in a 1/2WL thin-wire dipole, you can prove that dipole to be almost zero degrees long, just like you did with the coil. > In an attempt to justify your odd conclusions, you are now altering my > measurements. Please don't blame my faulty memory on any ulterior motive. It was an honest mistake easily proven to be wrong. (And a VF of 0.5 is just as unbelievable as a VF of 1.0 for a foot long 8 tpi coil.) > At this point any further exchange is useless, because you have now > resorted to calling the other person a liar when measured data > disagrees with your preconcieved notions. I apologize for my faulty memory, Tom, and everyone knows that I didn't call you a liar. I accidentally misquoted you and you corrected me. Your measured data simply disagrees with known technical facts. Until you take time to understand the technical implications behind the standing wave current phase that you used for your measurements, Itot = Io*cos(kx)*cos(wt) you will never understand why using such a signal to measure phase is an invalid thing to do. Hint: the phase of the above standing wave current doesn't vary with 'x' so it cannot be used to measure a phase shift between point 'x1' and point 'x2' on a wire or through a coil. -- 73, Cecil http://www.qsl.net/w5dxp Article: 223952 of rec.radio.amateur.antenna From: Buck Subject: TT-247 and 102 whip for mobile antenna ? testing Message-ID: References: <6na4521tmlo4ipifhhgo0u5dvt43t3l25c@4ax.com> Date: Sun, 30 Apr 2006 08:55:49 -0400 Yesterday I bought the whip and put it on my existing ball mount on the back left corner of my van. I still have the coax running to it so there is about 20 feet of RG-58 (RadioShack brand) running from the antenna to the tuner. My preliminary results weren't good. It tunes all ham bands from 6 thru 17 easily. 20 starts getting finicky and the bands below seem to cause arcing. On the receive side, I am able to receive much better with the CB whip than with either the 40 or 20 meter AS antennas on bands other than what the AS antennas are designed for. On transmit, things aren't so well. On 75 meters, I was able to hear one person acknowledge that there was a mobile calling. I heard no other response with any other band. Mind you, I was doing this from just about sunset until about 11 PM with a long break for supper and a short shopping trip. This wasn't the ideal time to test the antenna for any band other than 40 and 80. I heard some activity on 60 but no one responded to my call. Today, if I don't get called into work, I plan to cut the wire next to the antenna mount and install an SO-239 so I can wire the tuner directly to the antenna or connect the coax to run to the front of the van where I have the radio mounted. I will test the antenna and try to compare it to the 40 and 20 meter as antennas. Just for kicks and giggles, I stacked the two antenna bases for 20 and 40 meters and added the steel whip to the top of the combo (that's about 12 feet tall plus the height on the van.) The results weren't good. The steel whip was too heavy and caused the antenna to bow to the ground. I will try them today with and without the stinger to see if that is a better combination than just the one band antenna. hmm, 20 + 40, that's 60 meters, right? lol. It's 9 am here in Charlotte. I am going to read my email and go experiment some more. 73 for now. -- 73 for now Buck N4PGW Article: 223953 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: TT-247 and 102 whip for mobile antenna ? testing References: <6na4521tmlo4ipifhhgo0u5dvt43t3l25c@4ax.com> Message-ID: Date: Sun, 30 Apr 2006 13:26:10 GMT Buck wrote: > Today, if I don't get called into work, I plan to cut the wire next to > the antenna mount and install an SO-239 so I can wire the tuner > directly to the antenna or connect the coax to run to the front of the > van where I have the radio mounted. SGC recommends that no transmission line be used between the tuner and the antenna because of arcing. Consider that to force just one watt into a CB whip on 4 MHz, EZNEC says it takes over 1700 volts. -- 73, Cecil http://www.qsl.net/w5dxp Article: 223954 of rec.radio.amateur.antenna Message-ID: <4454C145.4020601@fuse.net> Date: Sun, 30 Apr 2006 09:53:09 -0400 From: jawod Subject: Re: blame the posters not arrl References: <22se42d1ndkmbrj99p6675l6k2t16rplk4@4ax.com> <1146238178.410103.29330@y43g2000cwc.googlegroups.com> <1146271643.734737.155940@j73g2000cwa.googlegroups.com> <3lm5521h52e4jgalekjqq6g64e3i59u1mm@4ax.com> <1146333073.590407.297500@i39g2000cwa.googlegroups.com> <1257hrlls8jm694@corp.supernews.com> <1146368310.284179.91600@j33g2000cwa.googlegroups.com> Guy wrote: > "an_old_friend" wrote in message > news:1146368310.284179.91600@j33g2000cwa.googlegroups.com... > >>Terry Two Shoes wrote: >> >>>"Dr.Death" wrote in message >>>news:1257hrlls8jm694@corp.supernews.com... >>>"Fred" wrote in message >>>news:cff752ptrbujv3st3o1r30ececm1f3oku4@4ax.com... >>> >>>>On 29 Apr 2006 10:51:13 -0700, "an_old_friend" >>>>wrote: >> >>>If passing a Ham test was predicated upon correct spelling, he'd be a >>>washout. >> >>but spelling corect on the fly is not requirement noris punkchuation >>spasing orany efert 2make it ezyon thu reedr >> > > > Thanks SO MUCH to everyone involved for ruining this NG with off-topic drivel. Another ham group washout. "Tis a pity. John AB8WH Article: 223955 of rec.radio.amateur.antenna Message-ID: <4454C4B7.4060503@fuse.net> Date: Sun, 30 Apr 2006 10:07:51 -0400 From: jawod Subject: Re: "interesting" antenna design References: <69488$4450c795$453d9423$12820@FUSE.NET> <12525ve803tkr07@corp.supernews.com> <3hd2525iugq7fnnabcpsqk32okj0ncklt7@4ax.com> Howard W3CQH wrote: > Another item that also works especially on 6m, throw an old bed spring on > the roof! > 73's > > "Owen Duffy" wrote in message > news:3hd2525iugq7fnnabcpsqk32okj0ncklt7@4ax.com... > >>On Thu, 27 Apr 2006 12:13:46 -0700, Roy Lewallen >>wrote: >> >> >>>jawod wrote: >>> >>>>I was listening to 40M the other night and a reasonably clear SSB signal >>>> came from a guy in Pennsylvania using 100 W to a rain gutter. >>>> >>>>It was apparently raining at the time in PA. >>>> >>>>All the mathematical modeling and tweaking discussed in this group ... >>>>I thought the successful use of a rain gutter deserved some praise here. >>> >>>Why? There's nothing unusual or exceptional about it. >> >>Indeed. >> >>Whilst it might have, and is probably still often done, it is unlikely >>to comply with limits on Maximum Permitted Exposure to EMR. It has a >>host of other disadvantages (EMC incompatibility, TVI/RFI, unreliable >>performance to name a few). >> >>The configuration is known as a CIA Special down here, being a covert >>antenna. I suppose it is commonly done in places where covenants >>prohibit external antennas. >> >>... >> >>>Anyone who's been a ham for a few years probably has a handful of >>>similar stories. What conclusions should we draw from them? >> >>Anything and everything "works" in the minds of amateurs. In the minds >>of some, a few QSOs is adequate proof that something "works", though I >>know you think differently Roy. >> >>Owen >>-- > > > I just think the great stories of rain gutters, chimneys, fire escapes, etc. reflect the spirit of individual experimentation that, to me, is the heart of ham radio. Maybe not the brain, but the heart. John AB8WH Article: 223956 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: "interesting" antenna design References: <69488$4450c795$453d9423$12820@FUSE.NET> <12525ve803tkr07@corp.supernews.com> <3hd2525iugq7fnnabcpsqk32okj0ncklt7@4ax.com> <4454C4B7.4060503@fuse.net> Message-ID: Date: Sun, 30 Apr 2006 14:29:48 GMT jawod wrote: > I just think the great stories of rain gutters, chimneys, fire escapes, > etc. reflect the spirit of individual experimentation that, to me, is > the heart of ham radio. Maybe not the brain, but the heart. You must love Kurt N. Sterba's tales of using bedsprings, ladders, and garbage cans for antennas. -- 73, Cecil http://www.qsl.net/w5dxp Article: 223957 of rec.radio.amateur.antenna From: Buck Subject: Re: TT-247 and 102 whip for mobile antenna ? testing Message-ID: References: <6na4521tmlo4ipifhhgo0u5dvt43t3l25c@4ax.com> Date: Sun, 30 Apr 2006 10:55:07 -0400 On Sun, 30 Apr 2006 13:26:10 GMT, Cecil Moore wrote: >Buck wrote: >> Today, if I don't get called into work, I plan to cut the wire next to >> the antenna mount and install an SO-239 so I can wire the tuner >> directly to the antenna or connect the coax to run to the front of the >> van where I have the radio mounted. > >SGC recommends that no transmission line be used between the >tuner and the antenna because of arcing. Consider that to >force just one watt into a CB whip on 4 MHz, EZNEC says it >takes over 1700 volts. Interesting. Thanks. I am still testing. I tested with coax and the result is that the antennas designed for a given frequency work much better on their frequencies. I am looking for my soldering kit now for the connectors. I may try a direct connection to see what happens without coax if I can. back in a few. n4pgw -- 73 for now Buck N4PGW Article: 223958 of rec.radio.amateur.antenna From: "Frank's" References: Subject: Re: A little more on missing degrees Message-ID: Date: Sun, 30 Apr 2006 15:12:18 GMT "Reg Edwards" wrote in message news:mrKdnUgqFMsZs8nZRVnyjg@bt.com... >I havn't much idea on what the present argument is all about. And I > have no wish to take sides. > > But - > > If Line-1 has impedance Zo1 and is a fractional wavelength L1 long, > > and Line-2 has impedance Zo2 and is a fractional wavelength L2 long, > > then when both lines are connected together and are brought into > so-called 1/4-wave resonance by pruning the length of one of the > lines, it is IMPOSSIBLE for L1 + L2 to equal 1/4-wavelength or 90 > degrees. > > There are ALWAYS some degrees "missing" - depending on the ratio > Zo1/Zo2. > > Except only when Zo1 = Zo2 will L1 + L2 total 90 degrees. > > Can be proved mathematically without invoking standing or reflected > waves. You just have to believe in mathematics. > > Line-1, of course, is a loading coil and Line-2 is a whip. > > I hope this settles an argument. > > For a demonstration download program TWOLINES from website below. I don't understand the argument either. Why would anyone care how many degrees an antenna has; it radiates all the power whatever its length. Frank Article: 223959 of rec.radio.amateur.antenna From: helmsman Subject: Re: blame the posters not arrl Date: Sun, 30 Apr 2006 11:33:29 -0400 Message-ID: References: <1146271643.734737.155940@j73g2000cwa.googlegroups.com> <3lm5521h52e4jgalekjqq6g64e3i59u1mm@4ax.com> <1146333073.590407.297500@i39g2000cwa.googlegroups.com> <1257hrlls8jm694@corp.supernews.com> <1146368310.284179.91600@j33g2000cwa.googlegroups.com> <4454C145.4020601@fuse.net> On Sun, 30 Apr 2006 09:53:09 -0400, jawod wrote: >Guy wrote: >> "an_old_friend" wrote in message >> news:1146368310.284179.91600@j33g2000cwa.googlegroups.com... >> >>>Terry Two Shoes wrote: >>> >>>>"Dr.Death" wrote in message >>>>news:1257hrlls8jm694@corp.supernews.com... >>>>"Fred" wrote in message >>>>news:cff752ptrbujv3st3o1r30ececm1f3oku4@4ax.com... >>>> >>>>>On 29 Apr 2006 10:51:13 -0700, "an_old_friend" >>>>>wrote: >>> >>>>If passing a Ham test was predicated upon correct spelling, he'd be a >>>>washout. >>> >>>but spelling corect on the fly is not requirement noris punkchuation >>>spasing orany efert 2make it ezyon thu reedr >>> >> >> >> >Thanks SO MUCH to everyone involved for ruining this NG with off-topic >drivel. > >Another ham group washout. "Tis a pity. > >John >AB8WH Kill file the posters. Article: 223960 of rec.radio.amateur.antenna From: Buck Subject: Re: TT-247 and 102 whip for mobile antenna ? test complete Message-ID: References: <6na4521tmlo4ipifhhgo0u5dvt43t3l25c@4ax.com> Date: Sun, 30 Apr 2006 12:29:54 -0400 I just finished testing my antennas. The result is that the whip/tuner combination is unacceptable. I took the coax off the ball mount and ran short wires, about 6 inches >from the center lead of the ball and from the ground screw at the ball inside the cab of the van and ran them to the appropriate connectors on the tuner. I then tested 75, 40, and 20 meters. The test results were that I made no contacts on 75. The only thing I heard was a very slow and long monolog on 3872 by some man who seemed more to be broadcasting than talking to another individual. I waited over ten minutes to see if he would break or identify, but he did neither. I went to 3.915 and heard two stations go QRT, but received no response when I called. I didn't have another antenna worth testing on 75 so that concluded my 75 meter test. Results: NO JOY! I went to 40 meters where I heard some conversations. It tuned up more easily than on 75, but no one answered my calls. I swapped to the 40 meter AS antenna and the stations I heard went from no signal on the scale to over s-9. That was enough to resolve that test. Results: NO JOY! I went to 20 meters where I had more success. I talked to Jim on the county hunter's net with the whip antenna. He was the only station I was hearing at the time. I swapped to the 20 meter AS antenna and his signal strength went from s-2 to s-9. Also, I was able to hear the mobile that was running. Results: NO JOY! I hooked the coax back up, setup the 20 meter AS antenna and tuned it >from the front of the car. I will not be drilling a hole and rearranging all the roof antennas for the whip. I will rather focus my attention on getting the rest of the parts of my screwdriver together after I get paid next week and see if I can install it. Thanks for all the comments. If nothing else, all this testing did reveal a bad ground connection >from the coax to the cab of the van. It is now fixed. 73 for now. -- 73 for now Buck N4PGW Article: 223961 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Velocity Factor and resonant frequency References: <12560ajs2oc286f@corp.supernews.com> <10935-44539EC6-55@storefull-3258.bay.webtv.net> <1146334972.592832.210040@v46g2000cwv.googlegroups.com> <7jU4g.77642$dW3.22733@newssvr21.news.prodigy.com> <1146380239.089435.216750@j33g2000cwa.googlegroups.com> <4i45g.77725$dW3.10759@newssvr21.news.prodigy.com> Message-ID: Date: Sun, 30 Apr 2006 17:29:09 GMT Tom Donaly wrote: > Everyone wants to use the most unreliable instrument they possess, their > brain, to measure natural phenomena. The Corum boys wrote an > entertaining paper that makes use of what is evidently an old > technique for explaining helical behavior in the microwave range > to make a point about self-resonant coils being superior to > coil-capacitor combinations for producing long sparks in > Tesla coils. Taken literally, the paper misses the magic > ingredient of validation by experimentation. Drs. Corum have published many papers which include experiments and measurements. The above referenced paper is the technical summation of theory and measurements. The other paper that I quoted contains all the experimental measurements that you could ask for. Enjoy. It is at: http://www.ttr.com/corum/index.htm -- 73, Cecil http://www.qsl.net/w5dxp Article: 223962 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: A little more on missing degrees References: Message-ID: Date: Sun, 30 Apr 2006 17:32:02 GMT Frank's wrote: > I don't understand the argument either. Why would anyone care > how many degrees an antenna has; it radiates all the power > whatever its length. Some of us care whether that radiation is heat or RF. :-) -- 73, Cecil http://www.qsl.net/w5dxp Article: 223963 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Velocity Factor and resonant frequency References: <12560ajs2oc286f@corp.supernews.com> <10935-44539EC6-55@storefull-3258.bay.webtv.net> <1146334972.592832.210040@v46g2000cwv.googlegroups.com> <7jU4g.77642$dW3.22733@newssvr21.news.prodigy.com> <1146380239.089435.216750@j33g2000cwa.googlegroups.com> <_X15g.18751$4L1.8107@newssvr11.news.prodigy.com> Message-ID: Date: Sun, 30 Apr 2006 18:10:59 GMT Tom Donaly wrote: > When are you guys going to do your own experiments and > measurements. I've already done them and reported them here, Tom. Here's the procedure again. 1. Take a sample coil and measure the 1/4WL self resonant frequency over my GMC pickup ground plane. 2. Keeping everything else the same, cut off half of the above coil. 3. Add enough straight wire as a stinger to bring the antenna system back to resonance at the previous self- resonant frequency. 4. The delay through half the coil at the self resonant frequency of the whole coil, is known to be 45 degrees. The stinger is 11 degrees long. The impedance discontinuity between the coil and the stinger provides the other 34 degrees of phase shift. Both sides of the argument assumed only two phase shifts were involved. Both sides were wrong. The third phase shift is obvious once you know it exists and is perfectly visible on a Smith Chart. When the impedance at Z01 is 1.0 on the Smith Chart and transforms to 9.0 on the Smith Chart for Z02, that's obviously a large phase shift. Two years ago, both sides agreed that the stinger was about 11 degrees of the antenna. 1. Side 1 said that the base loading coil acted as a purely lumped inductance providing 79 degrees of phase shift essentially at a point. 2. Side 2 said that the base loading coil provided a 79 degree delay like the delay in a transmission line, which was the source of the 79 degree phase shift. At that time, both sides were unaware of the phase shift occuring at the impedance discontinuity point. Now we know that both sides were partially right and partially wrong. As side 1 said, there is an abrupt phase shift at a point. As side 2 said, there is a delay through the coil. The truth seems to be just about in the middle of the two previous arguments which should make both sides happy. There are tens of degrees of delay through the coil. There are tens of degrees of abrupt phase shift at the coil to stinger impedance discontinuity. Both sides were equally right and equally wrong. Who won? Both sides. Who lost? Both sides. This is the invariable result when both sides are forced off the rails by reality. -- 73, Cecil http://www.qsl.net/w5dxp Article: 223964 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Wire diameter vs Impedance References: <1146256136.332525.320580@i39g2000cwa.googlegroups.com> <1146416277.330091.189340@j73g2000cwa.googlegroups.com> Message-ID: Date: Sun, 30 Apr 2006 18:15:58 GMT AC7PN wrote: > Bottom line, smaller wire means more inductance and a shorter lenght > for the same resonant frequency. Bigger wire means less inductance and > a longer length for the same resonant frequency. Why does EZNEC report that increasing the wire diameter results in lowering the resonant frequency? -- 73, Cecil http://www.qsl.net/w5dxp Article: 223965 of rec.radio.amateur.antenna From: Buck Subject: RoomCap Antenna Message-ID: Date: Sun, 30 Apr 2006 14:29:45 -0400 Can anyone tell me about this RoomCap Antenna? The best I can find on the antenna is a picture of what looks like a piece of PVC with a capacity hat on it. I keep getting advertisements on the email reflectors and when I check the website, it asks for me to email for more information. I have done so several times and never received a response. What can you all tell me about this antenna? Thanks, Buck -- 73 for now Buck N4PGW Article: 223966 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Insulation diameter vs Impedance OR how to get 20dBi out of a References: Message-ID: Date: Sun, 30 Apr 2006 18:39:11 GMT Richard Clark wrote: > Just in case there is nothing wrong with the model, I hereby cede this > to the public domain and this is notice of prior art. Years ago, I came up with an EZNEC model that has 24 dBi omnidirectional gain. It can be downloaded from: http://www.qsl.net/w5dxp/SUPRGAIN.EZ -- 73, Cecil http://www.qsl.net/w5dxp Article: 223967 of rec.radio.amateur.antenna From: Buck Subject: Re: Insulation diameter vs Impedance OR how to get 20dBi out of a short Dipole Message-ID: References: Date: Sun, 30 Apr 2006 14:44:29 -0400 On Sun, 30 Apr 2006 11:23:18 -0700, Richard Clark wrote: >Hi All, > >This is a variation on themes being played out. As the title >suggests, you too can force your modeler to give you phenomenal >results in just 5 minutes! Think of it, 20 dBi from a short Dipole - >but first the story: > >While I was pondering the coil current flow tricks, I mused over the >thought of instead loading a short antenna with the inverse of >inductance, capacitance. Instead of using suspect lumped loads, I >instead chose to load the wire with insulation. And not just any >insulation. > >Insulation found on typical wire comes in a vary small range of >values. They exhibit dielectric constants from 2 to 4, and rarely >that high. If I were to take a load of it, say in the form factor of >a Texas Bugcatcher coil - what would happen? > >Not much it seems. However, I am not one to let that slow me down and >I considered a list of elements and materials to examine them for the >highest DCs available. I was thinking of waxes primarily. The >thought ran that I would turn a small HF antenna into a candle and see >if that would slow the Vf. > >Waxes do offer higher DCs, but not markedly so. I started to think >salts next, considering that the common round salt box was about the >same size as a large coil. Salts have a high DC (up to the teens), >but even there, not much effect. > >Then I turned to what is commonly available, and exhibits a very high >DC - water (dielectric constant of 80). I started with a meter high >tube of 4 inches diameter (been thinking a lot about plumbing this >week when contractors built a French drain in the basement) and >plunked a short (5M) vertical antenna into it. > >THIS made a difference. (OK, so did others, but not like THIS). > >What the hell, I started to make the diameter bigger to see where the >limits of failure were. Turned out to be around 12 inches thick water >jacket. This was for a monopole in a truck bed I though (fair amount >of weight and sloshing in this linear load). However, it had the >intended consequence of providing 5.6dBi gain. > >Now, this gain has to be taken in the perspective of the unjacketed >radiator that exhibits -4.85dBi gain. More than 10dB gain by adding >this water jacket! Hosanna! Of course, if I trimmed this thickness >to goose up the gain, THEN the modeler failed with reports of negative >resistance (due to possible problems that could not possibly exist). > >Well, time to reduce complexity and do the same thing with a short >dipole in space (10M long excited at 3.8MHz). This antenna is >constructed with 10 wires so that only the first wires closest to the >feed are insulated. I increased the size of the water jacket and >noted results for drive point impedance, average gain, and best gain. >The binomial progression is edited from a longer list. The results >are as follows: > >Thickness Zfeed AvGain Gain > mm Ohms dB dB > 0 4.1 - J 1646 -0.02 1.77 > 10 3.726 - J 1437 0.039 2.17 > 20 3.498 - J 1305 0.66 2.45 > 40 3.2 - J 1133 1.05 2.83 > 80 2.848 - J 930 1.55 3.34 > 160 2.46 - J 705.8 2.19 3.98 > 320 2.051 - J 469.5 2.98 4.77 > 600 1.67 - J 249.5 3.87 5.66 > 1211.67 1.238 - J 0.0013 5.17 6.96 > 2200 0.8685 + J 213.2 6.71 8.5 > 4000 0.4971 + J 427.7 9.13 10.92 > 8000 0.0656 + J 676.9 17.93 19.71 > >As you can see, a water jacket 16 meters wide around the first >meter(s) of the dipole offer considerable gain and nothing suggesting >that further enlargement was going to upset this trend. I wasn't >going to push it anyway because it looked exceedingly suspicious. > >As suspicious as it may appear, it shows a rather smooth progression. >It was pleasing to note how the load reactance shifted from capacitive >to inductive. I posted a note to Roy who confirmed the intent for the >insulation entry was to limit it to common coating dimensions. >However, there is nothing in the data to suggest a logic breakdown in >my progressions. > >On the other hand, when I pushed this further by reducing the wire >size (10 wires per element instead of 5, while keeping the same total >length), I noticed the effect was more remarkable: > >Thickness Zfeed AvGain Gain > mm Ohms dB dB > 1000 0.2847 + J 139.9 10.98 12.76 > >A 1 meter water jacket on a shorter wire induced more gain than the >former 4 meter water jacket from the series of results above. > >To me, this suggested a boundary violation more so than a thickness >failure mechanism. There are cautions or prohibitions in connecting >different size wires, it seems that extends to insulations' diameter >mismates even when the wires' diameters (25.4mm) are identical >throughout. > >So, the object lesson seems to be > Do not try this at home, > or > in the back yard; > or > Do not fill your truck bed with water flooding your HF antenna > >73's >Richard Clark, KB7QHC > >p.s. >Just in case there is nothing wrong with the model, I hereby cede this >to the public domain and this is notice of prior art. I lived near a lake that has about a 3 mile circumference, what kind of gain could I expect if I sank my antenna in the lake and operated marine mobile from a wooden boat? -- 73 for now Buck N4PGW Article: 223968 of rec.radio.amateur.antenna From: Buck Subject: Icom auto-tune for screwdriver Message-ID: Date: Sun, 30 Apr 2006 14:48:08 -0400 http://www.qsl.net/w5dxp/706screw.htm Cecil has the above diagram. Tell me if I am wrong, but would not the Icom automatically stop tuning the antenna when the swr drops to it's low if it is below 1.5:1? -- 73 for now Buck N4PGW Article: 223969 of rec.radio.amateur.antenna From: "Frank's" References: Subject: Re: A little more on missing degrees Message-ID: Date: Sun, 30 Apr 2006 19:03:08 GMT "Cecil Moore" wrote in message news:mw65g.71196$H71.27541@newssvr13.news.prodigy.com... > Frank's wrote: >> I don't understand the argument either. Why would anyone care >> how many degrees an antenna has; it radiates all the power >> whatever its length. > > Some of us care whether that radiation is heat or RF. :-) > -- > 73, Cecil http://www.qsl.net/w5dxp A 15 ft long horizontal dipole, #14 AWG, on 3.8 MHz, has a radiation efficiency of 90.17%. The loss due to heat is 0.45 dB. Designing an efficient matching network may be difficult. Even with 100 W delivered to the antenna the 52 kV at the feedpoint may pose a problem. Frank Article: 223970 of rec.radio.amateur.antenna Message-ID: <445515A9.7020700@fuse.net> Date: Sun, 30 Apr 2006 15:53:13 -0400 From: jawod Subject: Re: "interesting" antenna design References: <69488$4450c795$453d9423$12820@FUSE.NET> <12525ve803tkr07@corp.supernews.com> <3hd2525iugq7fnnabcpsqk32okj0ncklt7@4ax.com> <4454C4B7.4060503@fuse.net> Cecil Moore wrote: > jawod wrote: > >> I just think the great stories of rain gutters, chimneys, fire >> escapes, etc. reflect the spirit of individual experimentation that, >> to me, is the heart of ham radio. Maybe not the brain, but the heart. > > > You must love Kurt N. Sterba's tales of using bedsprings, > ladders, and garbage cans for antennas. I don't know who Kurt ? is...maybe I would. If the calculations get out of hand...maybe I wouldn't. Wouldn't be weird if someone had to reverse engineer a garbage to define an antenna? Article: 223971 of rec.radio.amateur.antenna From: Roy Lewallen Subject: Re: Wire diameter vs Impedance Date: Sun, 30 Apr 2006 12:54:08 -0700 Message-ID: <125a5f49sbulm23@corp.supernews.com> References: <1146256136.332525.320580@i39g2000cwa.googlegroups.com> <1146416277.330091.189340@j73g2000cwa.googlegroups.com> A wonderfully logical explanation. But there's something wrong with it because the conclusion it reaches is demonstrably wrong. An antenna made with a larger diameter wire must be made shorter, not longer, than one with a smaller diameter wire to maintain the same resonant frequency. Roy Lewallen, W7EL AC7PN wrote: > . . . > Bottom line, smaller wire means more inductance and a shorter lenght > for the same resonant frequency. Bigger wire means less inductance and > a longer length for the same resonant frequency. > . . . Article: 223972 of rec.radio.amateur.antenna From: richardharrison@webtv.net (Richard Harrison) Subject: Re: Velocity Factor and resonant frequency Date: Sun, 30 Apr 2006 15:55:15 -0500 Message-ID: <9731-44552433-56@storefull-3254.bay.webtv.net> References: <1146380239.089435.216750@j33g2000cwa.googlegroups.com> Tom, W8JI wrote: "--Harrison probably hasn`t even owned a bug catcher coil being a technician class license holder." You don`t need to own things to understand them. I have a technician class radio amateur license renewed after its initial ten-hear term. My First FCC license was a 1st class radiotelephone license passed on my first attempt at the test in the Houston FCC Office in early 1949. Shortly thereafter I got a call from a Houston broadcaster that resulted in employment at a plant housing two AM atations which shared a common antenna system. From there I went to work in medium-wave and shortwave broadcasting stations for a dozen years, got several college degrees including a BSEE. I took a job with a petrochemical conglomerate which called me in 1960 saying that it intended to "automate" its operations and they thought I might be helpful. In their employment, I installed low-frequency aircraft beacons, 6-GHz microwave, shortwave AM, FM, and SSB. Installed telephones and electric power plants. The conglomerate found, produced, transported, traded, refined. manufactured and marketed oil and gas and products made from them. That was only a start. The company mined materials from the earth and from the sea bottom. It farmed, manufactured tractors and automobile components and tools. It built nuclear submarines, surface ships, natural gas tankers which consumed their own boil off, and it laid pipe across Canada and the U.S.A. It even consulted for other countries on the best ways to install and operate pipelines. I worked with a handfull of others for the subsidiary that did that for awhile. The company sold insurance because insurance companies have mush of the capital, and for a similar reason it bought and operated banks.. We made PVC and other chemical products. I worked in many of the company`s divisions when they asked for my services. We eventually put the pipeline divison under computer control from from Houston dispatcher`s office. Hundred of remotes were involved between Maine and Mexico. I`ve wound plenty of coils and tuned many mobile whips with my own hands. We used HF radios from Ecuador to Tierra del Fuego. I`ve worked on HF and VHF radios in the company`s aircraft. When I retired in 1986, I was manager of telecommunications. Best regards, Richard Harrison, KB5WZI Article: 223973 of rec.radio.amateur.antenna From: "Tom Donaly" Subject: Re: Insulation diameter vs Impedance OR how to get 20dBi out of a References: Message-ID: Date: Sun, 30 Apr 2006 21:11:57 GMT Richard Clark wrote: > Hi All, > > This is a variation on themes being played out. As the title > suggests, you too can force your modeler to give you phenomenal > results in just 5 minutes! Think of it, 20 dBi from a short Dipole - > but first the story: > > While I was pondering the coil current flow tricks, I mused over the > thought of instead loading a short antenna with the inverse of > inductance, capacitance. Instead of using suspect lumped loads, I > instead chose to load the wire with insulation. And not just any > insulation. > > Insulation found on typical wire comes in a vary small range of > values. They exhibit dielectric constants from 2 to 4, and rarely > that high. If I were to take a load of it, say in the form factor of > a Texas Bugcatcher coil - what would happen? > > Not much it seems. However, I am not one to let that slow me down and > I considered a list of elements and materials to examine them for the > highest DCs available. I was thinking of waxes primarily. The > thought ran that I would turn a small HF antenna into a candle and see > if that would slow the Vf. > > Waxes do offer higher DCs, but not markedly so. I started to think > salts next, considering that the common round salt box was about the > same size as a large coil. Salts have a high DC (up to the teens), > but even there, not much effect. > > Then I turned to what is commonly available, and exhibits a very high > DC - water (dielectric constant of 80). I started with a meter high > tube of 4 inches diameter (been thinking a lot about plumbing this > week when contractors built a French drain in the basement) and > plunked a short (5M) vertical antenna into it. > > THIS made a difference. (OK, so did others, but not like THIS). > > What the hell, I started to make the diameter bigger to see where the > limits of failure were. Turned out to be around 12 inches thick water > jacket. This was for a monopole in a truck bed I though (fair amount > of weight and sloshing in this linear load). However, it had the > intended consequence of providing 5.6dBi gain. > > Now, this gain has to be taken in the perspective of the unjacketed > radiator that exhibits -4.85dBi gain. More than 10dB gain by adding > this water jacket! Hosanna! Of course, if I trimmed this thickness > to goose up the gain, THEN the modeler failed with reports of negative > resistance (due to possible problems that could not possibly exist). > > Well, time to reduce complexity and do the same thing with a short > dipole in space (10M long excited at 3.8MHz). This antenna is > constructed with 10 wires so that only the first wires closest to the > feed are insulated. I increased the size of the water jacket and > noted results for drive point impedance, average gain, and best gain. > The binomial progression is edited from a longer list. The results > are as follows: > > Thickness Zfeed AvGain Gain > mm Ohms dB dB > 0 4.1 - J 1646 -0.02 1.77 > 10 3.726 - J 1437 0.039 2.17 > 20 3.498 - J 1305 0.66 2.45 > 40 3.2 - J 1133 1.05 2.83 > 80 2.848 - J 930 1.55 3.34 > 160 2.46 - J 705.8 2.19 3.98 > 320 2.051 - J 469.5 2.98 4.77 > 600 1.67 - J 249.5 3.87 5.66 > 1211.67 1.238 - J 0.0013 5.17 6.96 > 2200 0.8685 + J 213.2 6.71 8.5 > 4000 0.4971 + J 427.7 9.13 10.92 > 8000 0.0656 + J 676.9 17.93 19.71 > > As you can see, a water jacket 16 meters wide around the first > meter(s) of the dipole offer considerable gain and nothing suggesting > that further enlargement was going to upset this trend. I wasn't > going to push it anyway because it looked exceedingly suspicious. > > As suspicious as it may appear, it shows a rather smooth progression. > It was pleasing to note how the load reactance shifted from capacitive > to inductive. I posted a note to Roy who confirmed the intent for the > insulation entry was to limit it to common coating dimensions. > However, there is nothing in the data to suggest a logic breakdown in > my progressions. > > On the other hand, when I pushed this further by reducing the wire > size (10 wires per element instead of 5, while keeping the same total > length), I noticed the effect was more remarkable: > > Thickness Zfeed AvGain Gain > mm Ohms dB dB > 1000 0.2847 + J 139.9 10.98 12.76 > > A 1 meter water jacket on a shorter wire induced more gain than the > former 4 meter water jacket from the series of results above. > > To me, this suggested a boundary violation more so than a thickness > failure mechanism. There are cautions or prohibitions in connecting > different size wires, it seems that extends to insulations' diameter > mismates even when the wires' diameters (25.4mm) are identical > throughout. > > So, the object lesson seems to be > Do not try this at home, > or > in the back yard; > or > Do not fill your truck bed with water flooding your HF antenna > > 73's > Richard Clark, KB7QHC > > p.s. > Just in case there is nothing wrong with the model, I hereby cede this > to the public domain and this is notice of prior art. Hi Richard, try titanium dioxide next time. As long as you're looking for absurdist solutions it should work even better than water. 73, Tom Donaly, KA6RUH Article: 223974 of rec.radio.amateur.antenna From: Fred Subject: Re: blame the posters not arrl Message-ID: <33aa52hjph9c5e7bv6a0ihoonjttmsa7q4@4ax.com> References: <22se42d1ndkmbrj99p6675l6k2t16rplk4@4ax.com> <1146238178.410103.29330@y43g2000cwc.googlegroups.com> <1146271643.734737.155940@j73g2000cwa.googlegroups.com> <3lm5521h52e4jgalekjqq6g64e3i59u1mm@4ax.com> <1146333073.590407.297500@i39g2000cwa.googlegroups.com> <1257hrlls8jm694@corp.supernews.com> Date: Sun, 30 Apr 2006 21:14:13 GMT On Sat, 29 Apr 2006 15:07:19 -0500, "Dr.Death" wrote: >"Fred" wrote in message >news:cff752ptrbujv3st3o1r30ececm1f3oku4@4ax.com... >> On 29 Apr 2006 10:51:13 -0700, "an_old_friend" >> wrote: >> >>> >>>Fred wrote: >>>> On 28 Apr 2006 17:47:23 -0700, "an_old_friend" >>>> wrote: >>>> >>>> > >>>> >Fred wrote: >>>> >> On 28 Apr 2006 08:29:38 -0700, "an old freind" >>>> >> wrote: >>>> >> >>>> >> > >>>> > >>>> >> >> You said a mouthful. Oh and I agree with you. It just aint >>>> >> >> natural! >>>> >> >funny it occours outside of man and outside the primates in nature >>>> >> >all >>>> >> >the time >>>> >> >>>> >> So you are as stupid as a monkey or a dog? >>>> > >>>> >no you point? >>>> > >>>> >it looks like you are here to push your religous agenda and nothing to >>>> >with radio >>>> >>>> If you were smart enough to read you would find out that I do not >>>> believe in DOG. >>>I never stated you did >>>> I am just picking on you for being a militant pro-gay >>>> that is trolling Usenet groups looking for acceptance of his sick >>>> lifestyle. >>> >>>hardly you don't know what miliatant is >>> >>>you are psuhing you milltant religionous agenda where it desn't belong. >>>you have the right to do that, as I have the right to post what I see >>>fit >>>your problem is that you can't face the fact I have the same rights as >>>you do >>> >>>you want an end to defense of My Bisexaulity it can be had easiily >>> >>>you mustb( and the rest must refrain from atacking ti and refrain from >>>using the cry or "faggot" as an arguement in the NG >>> >>>it is that simple but the likes of you have proven you can't do it >> >> How many times do I have to tell you that I am an atheist? You can >> support and defend your faggotry all you want, but this is not the >> forum for that sick shit. You have no right to harass people in >> rec.radio.cb or any other newsgroup so suck on that you stupid turd >> pusher. > >And to this day he has yet to make an on topic post. I'll bet he was given >the answers while taking his ham test and still failed the first three >times. Makes me wonder if he even has radio equipment. > I am sure he has a mental retardation waiver. Article: 223975 of rec.radio.amateur.antenna From: "Tom Donaly" Subject: Re: Velocity Factor and resonant frequency References: <12560ajs2oc286f@corp.supernews.com> <10935-44539EC6-55@storefull-3258.bay.webtv.net> <1146334972.592832.210040@v46g2000cwv.googlegroups.com> <7jU4g.77642$dW3.22733@newssvr21.news.prodigy.com> <1146380239.089435.216750@j33g2000cwa.googlegroups.com> <4i45g.77725$dW3.10759@newssvr21.news.prodigy.com> Message-ID: Date: Sun, 30 Apr 2006 21:37:13 GMT Cecil Moore wrote: > Tom Donaly wrote: > >> Everyone wants to use the most unreliable instrument they possess, their >> brain, to measure natural phenomena. The Corum boys wrote an >> entertaining paper that makes use of what is evidently an old >> technique for explaining helical behavior in the microwave range >> to make a point about self-resonant coils being superior to >> coil-capacitor combinations for producing long sparks in >> Tesla coils. Taken literally, the paper misses the magic >> ingredient of validation by experimentation. > > > Drs. Corum have published many papers which include experiments > and measurements. The above referenced paper is the technical > summation of theory and measurements. The other paper that I > quoted contains all the experimental measurements that you could > ask for. Enjoy. It is at: > > http://www.ttr.com/corum/index.htm That's your idea of careful experimentation is it? First start out with a controversy that doesn't exist, then prove what everyone knows in the first place. So what part of the experimentation addresses the "sheath helix" model of their Tesla coil, Cecil? 73, Tom Donaly, KA6RUH Article: 223976 of rec.radio.amateur.antenna From: Jim - NN7K Subject: Re: "interesting" antenna design References: <69488$4450c795$453d9423$12820@FUSE.NET> <12525ve803tkr07@corp.supernews.com> <3hd2525iugq7fnnabcpsqk32okj0ncklt7@4ax.com> <4454C4B7.4060503@fuse.net> Message-ID: Date: Sun, 30 Apr 2006 22:04:26 GMT And, also, makes great Stacked helical's for 2304! Jim NN7K jawod wrote: > Howard W3CQH wrote: > >> Another item that also works especially on 6m, throw an old bed spring >> on the roof! >> 73's >> Article: 223977 of rec.radio.amateur.antenna From: Buck Subject: Re: Icom auto-tune for screwdriver Message-ID: References: Date: Sun, 30 Apr 2006 18:43:55 -0400 On Sun, 30 Apr 2006 22:24:12 GMT, Cecil Moore wrote: >Buck wrote: >> http://www.qsl.net/w5dxp/706screw.htm >> Cecil has the above diagram. Tell me if I am wrong, but would not the >> Icom automatically stop tuning the antenna when the swr drops to it's >> low if it is below 1.5:1? > >All that circuit does is reduce the power while tuning. >The operator is the only thing that can stop the tuning. ok, I thought it would drop the relay when the swr dropped. Thanks. -- 73 for now Buck N4PGW Article: 223978 of rec.radio.amateur.antenna From: "Tom Donaly" Subject: Re: Velocity Factor and resonant frequency References: <12560ajs2oc286f@corp.supernews.com> <10935-44539EC6-55@storefull-3258.bay.webtv.net> <1146334972.592832.210040@v46g2000cwv.googlegroups.com> <7jU4g.77642$dW3.22733@newssvr21.news.prodigy.com> <1146380239.089435.216750@j33g2000cwa.googlegroups.com> <_X15g.18751$4L1.8107@newssvr11.news.prodigy.com> Message-ID: Date: Sun, 30 Apr 2006 22:53:11 GMT Cecil Moore wrote: > Tom Donaly wrote: > >> In actuality, there's a constant change in Z0 up >> and down both the stinger and the coil so your idea is a >> bust. > > > The gradual change in Z0 really doesn't matter. What matters > is the *abrupt* change in Z0's at the coil to stinger impedance > discontinuity. That's where the abrupt phase shift occurs. Yes it does. 73, Tom Donaly, KA6RUH Article: 223979 of rec.radio.amateur.antenna From: "Yuri Blanarovich" References: <1146380239.089435.216750@j33g2000cwa.googlegroups.com> <9731-44552433-56@storefull-3254.bay.webtv.net> Subject: Re: Velocity Factor and resonant frequency Message-ID: Date: Sun, 30 Apr 2006 19:15:09 -0400 Hi Richard, Impressive carreer and background! That should slap another giant egg on the face of the technical imposter and "guru" parading as "know-it-all" riding on a high horse of plagiarized material. When he fails technical arguments, he resorts to name calling and insults. We still have to find out where he got his engineering degree and by what rights he uses "JI Engineering". Comparing your professional career to his "design" career like Dentron Clipperton L amplifier "capable" of producing barely 600W instead of 1200 on 160 due to joke of a final tank design and his digs at people illustrates the pathetic behavior. His modus operandi is to defend his wrong "knowledge", ridiculing and trivializing those who know better, then he realizes he was wrong, then he goes quiet for a while, then he twists and "adjusts" his arguments "showing" he said the same things, few months later he surfaces as a guru on the subject, proclaiming the gospel that he fought in the first place. Been there few times with him. He is incapable to engage in decent technical discussions if he thinks different. Will not admit being wrong, but will resort to personal digs when runs out of ammunition. BTW W9UCW and K8CFU did years of tests and measurements and shared some results pointing to the real behavior of the current in loading coils, but W8JI can make a coil that has the same current at both ends - end of story, because he proclaimed that current is ALWAYS the same and Kirchoff said so, never mind the reality of standing wave current. According to him, the RF chokes should not work either, let's hear some "'splanation". Oh well, there is bad apple in every RF barrel. 73, Yuri da BUm "Richard Harrison" wrote in message news:9731-44552433-56@storefull-3254.bay.webtv.net... > Tom, W8JI wrote: > "--Harrison probably hasn`t even owned a bug catcher coil being a > technician class license holder." > > You don`t need to own things to understand them. > > I have a technician class radio amateur license renewed after its > initial ten-hear term. My First FCC license was a 1st class > radiotelephone license passed on my first attempt at the test in the > Houston FCC Office in early 1949. Shortly thereafter I got a call from > a Houston broadcaster that resulted in employment at a plant housing two > AM atations which shared a common antenna system. From there I went to > work in medium-wave and shortwave broadcasting stations for a dozen > years, got several college degrees including a BSEE. > > I took a job with a petrochemical conglomerate which called me in 1960 > saying that it intended to "automate" its operations and they thought I > might be helpful. In their employment, I installed low-frequency > aircraft beacons, 6-GHz microwave, shortwave AM, FM, and SSB. Installed > telephones and electric power plants. > > The conglomerate found, produced, transported, traded, refined. > manufactured and marketed oil and gas and products made from them. That > was only a start. The company mined materials from the earth and from > the sea bottom. It farmed, manufactured tractors and automobile > components and tools. It built nuclear submarines, surface ships, > natural gas tankers which consumed their own boil off, and it laid pipe > across Canada and the U.S.A. It even consulted for other countries on > the best ways to install and operate pipelines. I worked with a handfull > of others for the subsidiary that did that for awhile. The company sold > insurance because insurance companies have mush of the capital, and for > a similar reason it bought and operated banks.. We made PVC and other > chemical products. I worked in many of the company`s divisions when they > asked for my services. We eventually put the pipeline divison under > computer control from from Houston dispatcher`s office. Hundred of > remotes were involved between Maine and Mexico. > > I`ve wound plenty of coils and tuned many mobile whips with my own > hands. We used HF radios from Ecuador to Tierra del Fuego. I`ve worked > on HF and VHF radios in the company`s aircraft. When I retired in 1986, > I was manager of telecommunications. > > Best regards, Richard Harrison, KB5WZI > Article: 223980 of rec.radio.amateur.antenna From: Fred Subject: Re: blame the posters not arrl Message-ID: <13ja521a4t9lajqiiajd47h1siohf5vf8h@4ax.com> References: <1146238178.410103.29330@y43g2000cwc.googlegroups.com> <1146271643.734737.155940@j73g2000cwa.googlegroups.com> <3lm5521h52e4jgalekjqq6g64e3i59u1mm@4ax.com> <1146333073.590407.297500@i39g2000cwa.googlegroups.com> <1257hrlls8jm694@corp.supernews.com> <33aa52hjph9c5e7bv6a0ihoonjttmsa7q4@4ax.com> <1146434087.455556.152410@u72g2000cwu.googlegroups.com> Date: Sun, 30 Apr 2006 23:48:03 GMT On 30 Apr 2006 14:54:47 -0700, "an old friend" wrote: > >Fred wrote: >> On Sat, 29 Apr 2006 15:07:19 -0500, "Dr.Death" >> wrote: > >> >> I am sure he has a mental retardation waiver. > >for what? > >I have a valid license and radio equipment what would I need a waver >for? Hmmm, you tell us. You certainly don't seem too bright. I am merely making an observation of a known quantity. You act like a retard so therefore I assume that you are a retard. Die of HIV, loser. Article: 223981 of rec.radio.amateur.antenna From: larry d clark Subject: Re: RoomCap Antenna References: Message-ID: Date: Mon, 01 May 2006 00:07:08 GMT Buck wrote: > Can anyone tell me about this RoomCap Antenna? > > The best I can find on the antenna is a picture of what looks like a > piece of PVC with a capacity hat on it. > > I keep getting advertisements on the email reflectors and when I check > the website, it asks for me to email for more information. I have > done so several times and never received a response. > > What can you all tell me about this antenna? > > Thanks, > Buck > http://home.datacomm.ch/hb9abx/ant--abx-e.htm larry kd5foy Article: 223982 of rec.radio.amateur.antenna From: Buck Subject: Re: RoomCap Antenna Message-ID: <9pqa529e7699iqm0jbenupurieou79u1ro@4ax.com> References: Date: Sun, 30 Apr 2006 22:00:00 -0400 On Mon, 01 May 2006 00:07:08 GMT, larry d clark wrote: >Buck wrote: >> Can anyone tell me about this RoomCap Antenna? >> >> The best I can find on the antenna is a picture of what looks like a >> piece of PVC with a capacity hat on it. >> >> I keep getting advertisements on the email reflectors and when I check >> the website, it asks for me to email for more information. I have >> done so several times and never received a response. >> >> What can you all tell me about this antenna? >> >> Thanks, >> Buck >> > >http://home.datacomm.ch/hb9abx/ant--abx-e.htm > >larry >kd5fo Thanks, larry, but I have been there. There is not information directly related to the antenna other than the hype about the antenna >from the maker. I wanted to know more details about whether or not it is good and just how it is made up. -- 73 for now Buck N4PGW Article: 223983 of rec.radio.amateur.antenna From: "Robert Lay (W9DMK)" Subject: Re: Velocity Factor and resonant frequency Date: Sun, 30 Apr 2006 23:26:08 -0400 Message-ID: <5rva521398tlbk0dbn4g96jsafkqdj2mdb@4ax.com> References: <1146380239.089435.216750@j33g2000cwa.googlegroups.com> <9731-44552433-56@storefull-3254.bay.webtv.net> On Sun, 30 Apr 2006 15:55:15 -0500, richardharrison@webtv.net (Richard Harrison) wrote: >Tom, W8JI wrote: >"--Harrison probably hasn`t even owned a bug catcher coil being a >technician class license holder." > >You don`t need to own things to understand them. > >I have a technician class radio amateur license renewed after its >initial ten-hear term. My First FCC license was a 1st class >radiotelephone license passed on my first attempt at the test in the >Houston FCC Office in early 1949. Shortly thereafter I got a call from >a Houston broadcaster that resulted in employment at a plant housing two >AM atations which shared a common antenna system. From there I went to >work in medium-wave and shortwave broadcasting stations for a dozen >years, got several college degrees including a BSEE. > >I took a job with a petrochemical conglomerate which called me in 1960 >saying that it intended to "automate" its operations and they thought I >might be helpful. In their employment, I installed low-frequency >aircraft beacons, 6-GHz microwave, shortwave AM, FM, and SSB. Installed >telephones and electric power plants. > >The conglomerate found, produced, transported, traded, refined. >manufactured and marketed oil and gas and products made from them. That >was only a start. The company mined materials from the earth and from >the sea bottom. It farmed, manufactured tractors and automobile >components and tools. It built nuclear submarines, surface ships, >natural gas tankers which consumed their own boil off, and it laid pipe >across Canada and the U.S.A. It even consulted for other countries on >the best ways to install and operate pipelines. I worked with a handfull >of others for the subsidiary that did that for awhile. The company sold >insurance because insurance companies have mush of the capital, and for >a similar reason it bought and operated banks.. We made PVC and other >chemical products. I worked in many of the company`s divisions when they >asked for my services. We eventually put the pipeline divison under >computer control from from Houston dispatcher`s office. Hundred of >remotes were involved between Maine and Mexico. > >I`ve wound plenty of coils and tuned many mobile whips with my own >hands. We used HF radios from Ecuador to Tierra del Fuego. I`ve worked >on HF and VHF radios in the company`s aircraft. When I retired in 1986, >I was manager of telecommunications. > >Best regards, Richard Harrison, KB5WZI Bravo, Richard! Article: 223984 of rec.radio.amateur.antenna From: "Sal M. Onella" References: <1146008591.641742.237030@y43g2000cwc.googlegroups.com> <4tjt42lg6k5ustfmiljfkpiqdle084d0iq@4ax.com> <96N4g.77517$dW3.54166@newssvr21.news.prodigy.com> Subject: Re: J_Pole Trials and Tribulations Message-ID: Date: Sun, 30 Apr 2006 20:43:10 -0700 "Bob" wrote in message news:96N4g.77517$dW3.54166@newssvr21.news.prodigy.com... > The J-pole crowd seems to tout fantastic claims about this antenna and I > have never been impressed. Many people have tested the J-pole against > other easy to make antennas and the end fed half wave J-pole usually > does not stand up to even it’s brother, the center fed half wave dipole. > I assume the decrease in performance is due to mistakes in assembling > and tuning the matching section. Here is a link to a group that tested > some J-poles against other antennas in the CA desert and the J-pole lost > to even simple 1/4 wave ground plane types. > www.geocities.com/SiliconValley/2775/anttest.html < snip > A quick look at the numbers doesn't make the j-pole look so all-fired bad. "Losing" by 1 dB or so isn't a serious loss. Ham radio isn't exactly the Kentucky Derby. I don't know what "fantastic claims" you've heard, but my affinity for the j-pole comes from its simplicity and durability. It's a halfwave vertical that requires no ground plane and can often be matched to 1:1 at the sweet spot. Mounting is a dream -- it even works if you drop the low end into a plumbing vent pipe. (How would I know that? ;-) I have never built a center-fed halfwave, but we use a bunch of them in the Navy -- call them "stovepipes" because of the way the fiberglass housings look -- and they work very, very well. The elements are large metal cylinders, tending to make them quite broadband. I do not know how they're fed ... balun or what. John , KD6VKW Article: 223985 of rec.radio.amateur.antenna From: "Sal M. Onella" References: <69488$4450c795$453d9423$12820@FUSE.NET> <12525ve803tkr07@corp.supernews.com> <3hd2525iugq7fnnabcpsqk32okj0ncklt7@4ax.com> <4454C4B7.4060503@fuse.net> Subject: Re: "interesting" antenna design Message-ID: Date: Sun, 30 Apr 2006 20:52:50 -0700 "jawod" wrote in message news:4454C4B7.4060503@fuse.net... < snip > > I just think the great stories of rain gutters, chimneys, fire escapes, > etc. reflect the spirit of individual experimentation that, to me, is > the heart of ham radio. Maybe not the brain, but the heart. > > John > AB8WH Me too. Oh, how much fun we have right after saying, "I wonder what happens if ... " Yeah, sometimes it's a burnt finger or a blown fuse, but even then we usually benefit from it.