Article: 221502 of rec.radio.amateur.antenna From: richardharrison@webtv.net (Richard Harrison) Subject: Re: Passive Repeater Date: Mon, 6 Feb 2006 20:34:47 -0600 Message-ID: <7443-43E80747-546@storefull-3257.bay.webtv.net> References: <9fSFf.10664$915.8953@southeast.rr.com> Bryan Martin wrote: "Was this supposed to help or was it just a slam?" No, my response was factual, neumeric, and specific. It was not meant as a slam. Reflectors are less lossy than back-to-back antennas. If you are using microwaves, the size of the reflector may be practical. The peflector in the path is most effective when placed near either end of the path. The reflector can also produce gain over that produced by the antennas at the path ends. It must be slightly concave to do so. Commercial reflectors often come equipped with an adjustment to suck in the center of the reflector for maximum gain once alignment of the dishes is accomplished. This isn`t speculation. I`ve designed the paths and performed the adjustments with my own hands. Best regatds, Richard Harrison, KB5WZI Article: 221503 of rec.radio.amateur.antenna From: richardharrison@webtv.net (Richard Harrison) Subject: Re: Verticals versus Horizontal Dipoles Date: Mon, 6 Feb 2006 21:12:24 -0600 Message-ID: <1331-43E81018-167@storefull-3255.bay.webtv.net> References: Reg, G4FGQ wrote: "The angle of the "horizontal" dipole relative to the horizon, whether it is an inverted V or not, makes negligible difference to the amount of noise it collects." It could be taken to the extreme. Rotated 90-degrees, the horizontal wire becomes a vertical wire. On its way to becoming a vertical wire, it is a sloping wire. The sloping wire responds with a vertical component in addition to its horizontal component. The sum of these components make up the wire`s total response. To the best of my knowledge, Reg hit the nail squarely on the head in the rest of his posting about noise radiation and reception. Best regards, Richard Harrison, KB5WZI Article: 221504 of rec.radio.amateur.antenna From: "J. Mc Laughlin" Subject: Re: Verticals versus Horizontal Dipoles Date: Mon, 6 Feb 2006 22:49:05 -0500 Message-ID: <11ug61r5qor0f6d@corp.supernews.com> References: <1138866750.041474.65870@g49g2000cwa.googlegroups.com> <1138961472.184345.67410@g44g2000cwa.googlegroups.com> <11u93rpp6sqo61e@corp.supernews.com> <176au1dd5a0s6nbri5728ml0ql1j1e1l7j@4ax.com> <11udhp9n9si5kee@corp.supernews.com> Dear Richard: You have said it so well! I fell for the taunt of the tar-baby. Thank you for the literate and appropriate quote from Johnson. For some unexplainable reason, I once read all of Boswell's journals. I had more time in those days. 73 Mac N8TT -- J. Mc Laughlin; Michigan U.S.A. Home: JCM@Power-Net.Net "Richard Clark" wrote in message news:f8kdu19qrac45savp37igbskevmvadjdi5@4ax.com... > On Sun, 5 Feb 2006 22:50:55 -0500, "J. Mc Laughlin" > wrote: > > >Reg: Your making such an obviously false statement calls into question > >all of your pronouncements. > > There is not a single student in my University (or any other similar > >institution that I know of) who will graduate without providing many > >demonstrations of their significant arithmetic and mathematical ability. > > Your veracity is gone. > > > C'Mon Mac, > > Reggie has been doing this so many years, it's his trademark schtick. > To give Reggie credit where credit is due, can be found in a > remarkable body of work of programs. Unfortunately, this > accomplishment is seriously tipped out of balance when he scorns his > audience as software addicts. > > Instead of teaching them Kelvin's principles by example, we get his > poor English stagings of Le Misanthrope de Moliere. > > One of my favorite irascible English characters is Dr. Samuel Johnson, > but his ire is tempered with a faith in humanity: > "this boy rows us as well without learning, as if he could sing > the song of Orpheus to the Argonauts, who were the first sailors.' > He then called to the boy, 'What would you give, my lad, to know > about the Argonauts?' 'Sir (said the boy,) I would give what I > have.' Johnson was much pleased with his answer, and we gave him a > double fare. Dr. Johnson then turning to me, 'Sir, (said he) a > desire of knowledge is the natural feeling of mankind; and every > human being, whose mind is not debauched, will be willing to give > all that he has to get knowledge.' " > > 73's > Richard Clark, KB7QHC Article: 221505 of rec.radio.amateur.antenna From: "Reg Edwards" Subject: Re: Verticals versus Horizontal Dipoles Date: Tue, 7 Feb 2006 04:36:34 +0000 (UTC) Message-ID: References: <1331-43E81018-167@storefull-3255.bay.webtv.net> Regardless of its noise properties, a quarter-wave and higher vertical radiates more low-angle power than a half-wave horizontal dipole. There's no argument. If you can't be heard then you can't work 'em. Although a quarter-wave vertical radiates less power at high angles, it can still be heard quite well because propagation distances covered are relatively short. The vertical is omni-directional. The dipole is not. Skip-distances are the same for both vertical and horizontal. The Ancient Greeks Geometry rules. Therefore, the situation is biassed in favor of the vertical. The dipole wins only when the local noise level is much higher than atmospheric noise. If you live in or near a city then its your hard luck. Most of us do! ---- Reg. Article: 221506 of rec.radio.amateur.antenna From: Roy Lewallen Subject: Re: Verticals versus Horizontal Dipoles Date: Mon, 06 Feb 2006 21:01:36 -0800 Message-ID: <11ugadllou7lsff@corp.supernews.com> References: <1138866750.041474.65870@g49g2000cwa.googlegroups.com> <1138961472.184345.67410@g44g2000cwa.googlegroups.com> <11u93rpp6sqo61e@corp.supernews.com> <176au1dd5a0s6nbri5728ml0ql1j1e1l7j@4ax.com> <11uadmer968m2a2@corp.supernews.com> Mike Coslo wrote: > Roy Lewallen wrote: > >> >> A step attenuator which is completely adequate for HF and can easily >> resolve 1 dB can be made from a few cheap slide switches, some PC >> board material, and a handful of ordinary 5% quarter watt resistors. >> Detailed instructions can be found in numerous sources, including the >> Web -- a Google search brought a large number of hits, the first of >> which was http://www.arrl.org/tis/info/pdf/9506033.pdf. But I'm afraid >> that this level of homebrewing is beyond the interest if not the >> ability of the majority of today's amateurs. > > > Got it - Thanks, Roy! > > - 73 de Mike KB3EIA - You're very welcome. The reason for my rather grumpy comment at the end is that I've recommended countless times for many years that people interested in evaluating antennas build a simple step attenuator -- an evening project. It allows you to make direct, quantitative comparisons between two antennas -- yours or someone else's, as well as calibrate your "S" meter. But to date, I've never gotten an iota of feedback that a single person has actually taken the trouble to build one. Rather, they continue to debate, ad nauseum and without any meaningful data, whether one antenna is better than the other, or at best quote differences in "S-units" read from their meters, without the foggiest idea how many dB it might represent or how different it is from someone else's meter (or >from the same meter on a different band or a different part of the scale). The conclusion I've reached is that A) Hams would much rather argue than actually determine the facts, or B) The vast majority are unable to build a homebrew project consisting of slide switches, circuit board material, and resistors. I'm afraid both are probably true. Maybe you'll be the first to actually build one. If so, please drop me an email and let me know -- it'll make my day! Roy Lewallen, W7EL Article: 221507 of rec.radio.amateur.antenna From: "Reg Edwards" Subject: Re: Verticals versus Horizontal Dipoles Date: Tue, 7 Feb 2006 06:05:01 +0000 (UTC) Message-ID: References: <1138866750.041474.65870@g49g2000cwa.googlegroups.com> <1138961472.184345.67410@g44g2000cwa.googlegroups.com> <11u93rpp6sqo61e@corp.supernews.com> <176au1dd5a0s6nbri5728ml0ql1j1e1l7j@4ax.com> <11uadmer968m2a2@corp.supernews.com> <11ugadllou7lsff@corp.supernews.com> "Roy Lewallen" wrote > The reason for my rather grumpy comment at the end is that I've > recommended countless times for many years that people interested in > evaluating antennas build a simple step attenuator -- an evening > project. ======================================== Roy, to cheer you up, many years back I made one in a diecast Eddystone box. The last decade was in 0.001 dB steps. It was intended only up to 5 MHz. It was used to determine the attenuation/temperature coefficients of oceanic, submarine coaxial cables, 26 miles long, in tanks at the cable factory. Temperature was changed by dumping a ton of ice into the tank, obtained from Billingsgate, London, fish market. I think the fish market is still in Billingsgate but the attenuator has long since disappeared. Perhaps the knobs still exist somewhere. Very sad! ---- Reg. Article: 221508 of rec.radio.amateur.antenna From: "Hal Rosser" References: <7_MFf.10650$915.3051@southeast.rr.com> <96okb3-td.ln1@p400bob.personal.cox.net> Subject: Re: Passive Repeater Message-ID: Date: Tue, 7 Feb 2006 01:14:25 -0500 Example scenario: There's a mountain between your house and the tv station and you cannot pick up a tv signal to watch. SO - you buy 3 high-gain direction tv antennas at radio shack. You go up to the top of the mountain and set one antenna to point to the tv station, and one of the other antennas to point toward your house. The 2 antennas on the mountain feed to each other with 300-ohm ribbon cable- like the other antenna was the tv set. (one acts like a receiver, and the other like a transmitter.) The third high-gain antenna is at your house - pointed to the antenna on top of the mountain. This antenna feeds to your tv. So yes - you need directional antennas - three of them. The antennas need to 'see' each other. I heard of folks using rhombic antennas on the mtn (uhf and vhf) - good gain. "Bryan Martin" wrote in message news:eeSFf.10663$915.3480@southeast.rr.com... > The building location is maybe 500 feet away from where the repeater would > be. The parabolic grid is maybe 3000-3500 feet away from the repeater > location. > > As for the output we will talk about the grid antenna first. It is Article: 221509 of rec.radio.amateur.antenna Subject: Re: Pulley Arrangement For Horiz. Antenna ? From: Dave Oldridge References: Message-ID: Date: Tue, 07 Feb 2006 06:23:57 GMT "Robert11" wrote in news:l7SdnRxtINYOzX7eRVn-iA@comcast.com: > Hi, > > Pretty sure I'll probably be able to come up with something that will > more or less work, but was wondering if any of you folks have a real > clever solution for this: > > Will be stringing a horiz wire listening only antenna between two > trees out back. > Trees have a fair amount of movement, particularly in the winter. > > So, I thought I'd fasten one end securely, and then use the pulley > arrangement, with a hanging weight, like you see in all the pix for > this sort of thing. > > But, we get a lot of ice and freezing rain, and I doubt that the > pulley would really function well, if at all in the winter. > But, perhaps ? > > Think a large metal ring, with a Dacron rope goint thru (one end to > the wire end) would be better ? > Coat Dacron with Silicone Spray ? Basic rule of thumb: If an antenna stays up all winter it wasn't big enough. -- Dave Oldridge+ ICQ 1800667 Article: 221510 of rec.radio.amateur.antenna From: jimg Subject: 160m antenna Message-ID: Date: Tue, 07 Feb 2006 07:58:15 GMT Hi. I'm looking for more creative ideas. I live in a typical suburban setting. I have a 100' oak tree out back with a clear base of 65' on to one side; 75' to the other. I've EZNEC'd a variety of antennas from center fed (ladder line) inverted vee resonant at about 2.4MHz. Moved to offset fed versions which works over more bands but still not quite a low enough swr to load with a palstar balanced tuner on 160. Moved on to a 'triangle' antenna made by adding a wire base to the inverted vee about 2-' off the ground. Now I've got enough length, but the swr is squirrely on all abnds because of the interaction of the short legs (I guess it's a short delta with only the driven element.). So, it appears I'll have to wait until the kids graduate and a move to the countryside is in order. I know it won't work as well as a wavelength loop with a huge mesh metal fence counterpoise, but it would be nice to try and ragchew on 160m while the sunspot cycle is zilch. Any weird topologies come to mind? And still let me load up 80/40m? jimg Oregon USA Article: 221511 of rec.radio.amateur.antenna From: Roy Lewallen Subject: Re: Passive Repeater Date: Tue, 07 Feb 2006 02:04:57 -0800 Message-ID: <11ugs6fc94rabf4@corp.supernews.com> References: <7_MFf.10650$915.3051@southeast.rr.com> <96okb3-td.ln1@p400bob.personal.cox.net> I keep hearing about "passive repeaters", but haven't ever seen anything quantitative about how well they work. I had some measurements done years ago which showed that a cell phone "passive repeater" in a sedan doesn't do anything significant, quite obviously because the windows are such large apertures at that frequency. But here are some numbers to work with. Corrections are welcome. Assuming perfect efficiency, the maximum effective aperture of an antenna is Aem = G * lambda^2 / (4 * pi), where lambda = the wavelength G = the antenna's numerical power gain in the direction being analyzed The gain in dBi = 10 * log[base10](G). For convenience, use meters for length dimensions, so the aperture is in square meters and the wavelength is in meters. This means that if we have a field with power density Pdi striking an antenna with power gain G1 (in the direction the field is coming from), the antenna can deliver Pdi * Aem watts to a conjugately matched load. Now let's connect this antenna to a second antenna with numerical power gain G2, and assume that the two are perfectly matched to each other. That is, the input impedance of the second antenna is the complex conjugate of the impedance the first antenna has when driven. Also assume no loss in the connecting line. The power delivered to the second antenna is then Pdi * Aem watts. The second antenna will radiate a field with power density equal to G2 times that of an isotropic antenna supplied with the same power, or G2 * (Pdi * Aem) / (4 * pi * r^2) where r is the distance from the antenna in the direction in which the gain is measured. Combining these to find the ratio of power density of the field radiated >from the second antenna to the power density of the field striking the first antenna, we get: P density ratio = G1 * G2 * (lambda / (4 * pi * r))^2 This is the numerical gain you'll see between the field at the location of the first passive receiver antenna to the field at a distance r from the second (radiating) passive receiver antenna. A ratio of less than one represents attenuation rather than gain. The gain in dB is 10 * the base 10 logarithm of this ratio, with negative results representing attenuation. That is, Overall gain (dB) = 10 * log[base 10](P density ratio) Now let's look at a couple of examples. For simplicity, assume that none of the original field arrives at the detector location; that is, there's a perfect shield or obstruction between the original field and the detector (technically, the detector's antenna). It doesn't matter what kind of antenna is physically connected to the detector for this analysis. In real life, the detector would probably be a receiver, but I'll call it a detector so hopefully its antenna won't be confused for either of the two passive receiver's antennas. Let G1 = G2 = 10 -- both antennas comprising the passive repeater have 10 dBi gain (although don't forget that G1 and G2 are numerical, not dB gains -- the two numbers just happen to be the same in the case of 10). Wavelength = 30 meters (10 MHz frequency), and r = 10 meters -- we've put the detector's antenna 10 meters from the second (radiating) passive repeater antenna(*). Working through the numbers, the power density at the detector's antenna is 5.7 times, or 7.56 dB greater than, the power density striking the first antenna. So the signal is stronger than it would have been if we'd put the detector's antenna right where the first passive repeater antenna is. Don't forget, though, that it took two 10 dBi antennas to get that 7.56 dB gain. But now let's look at the same setup but at 150 MHz (2 meter wavelength). The power density at the detector's antenna in this case is just 2.5% of (or 15.96 dB less than) the power density of the field striking the first antenna. In all cases, if we move the detector's antenna twice as close to the second (radiating) passive repeater antenna, that is, to 5 meters away, we'll gain 6 dB; if we double the distance to 20 meters we lose 6 dB. Before you say, "Aha! let's put the detector antenna 0.000001 meter from the passive repeater antenna and get incredible gain!" you have to realize that the antenna gain is achieved only in the far field, so you've got to keep a good part of a wavelength away for the rules to hold. Actually, 5 meters is almost certainly too close for the gain to be valid at 10 MHz. The actual gain at any distance and field strength for a given input power could easily be determined for a particular antenna by modeling. Why does the wavelength make such a big difference? Well, think of the size of the field each antenna intercepts. Both the 10 MHz and 150 MHz antennas have the same gain, so the former is dimensionally 15 times larger than the latter, or 15^2 = 225 times the area. Consquently, the 10 MHz antenna intercepts 225 times the power that the 150 MHz antenna does(**). 225 is exactly the ratio between the 10 and 150 MHz results of 5.7 and 0.025 (if carried out a few more places). If you know how much signal strength margin you have at the point where you put the first passive receiver antenna, you can use the equation above to calculate how much antenna gain you'll need for your passive repeaters and how close you'll have to put your receiver's antenna to the second (radiating) passive receiver antenna, or how to trade the two. Note that I've assumed perfect match and no loss. If, for example, there's loss in the transmission line between the two passive repeater antennas, that loss in dB will directly subtract from the overall passive repeater gain (or add to the overall passive repeater attenuation). (*) 10 meters is only 1/3 wavelengh so a bit close. The nominal antenna gain might not actually be realized at that short distance. But I'll assume it is. (**) Please don't infer from this that aperture has any obvious relationship to physical antenna area except in so-called "aperture antennas" such as horns or parabolic antennas which have large physical dimensions. The antennas under discussion have apertures proportional to their physical areas only because they're assumed to be physically identical except for a scaling factor. In general, antennas with widely different physical areas can have the same aperture, and antennas with the same physical area can have widely different apertures. Roy Lewallen, W7EL Article: 221512 of rec.radio.amateur.antenna From: ema32@msn.com Subject: Great Job Board Date: 07 Feb 2006 10:29:32 GMT Message-ID: <43e8768c$9$5507$bb8e7a08@news.usenetcompany.com> --_NextPart_00009763-000008F1-0CFDD265-11F2 Content-Type: text/plain Content-Transfer-Encoding: 7bit There is a great job board located at the employment section of http://www.4charlesson.com . So pass it on to anyone looking for a job. --_NextPart_00009763-000008F1-0CFDD265-11F2-- Article: 221513 of rec.radio.amateur.antenna From: "Mike Coombes" References: <7_MFf.10650$915.3051@southeast.rr.com> <96okb3-td.ln1@p400bob.personal.cox.net> <11ugs6fc94rabf4@corp.supernews.com> Subject: Re: Passive Repeater Date: Tue, 7 Feb 2006 18:32:01 +0800 Message-ID: <43e87729$0$30446$5a62ac22@per-qv1-newsreader-01.iinet.net.au> "Roy Lewallen" wrote in message news:11ugs6fc94rabf4@corp.supernews.com... >I keep hearing about "passive repeaters", but haven't ever seen anything >quantitative about how well they work. I had some measurements done years >ago which showed that a cell phone "passive repeater" in a sedan doesn't do >anything significant, quite obviously because the windows are such large >apertures at that frequency. > > But here are some numbers to work with. Corrections are welcome. > > Assuming perfect efficiency, the maximum effective aperture of an antenna > is Aem = G * lambda^2 / (4 * pi), where > > lambda = the wavelength > G = the antenna's numerical power gain in the direction being analyzed > > The gain in dBi = 10 * log[base10](G). For convenience, use meters for > length dimensions, so the aperture is in square meters and the wavelength > is in meters. > > This means that if we have a field with power density Pdi striking an > antenna with power gain G1 (in the direction the field is coming from), > the antenna can deliver Pdi * Aem watts to a conjugately matched load. > > Now let's connect this antenna to a second antenna with numerical power > gain G2, and assume that the two are perfectly matched to each other. That > is, the input impedance of the second antenna is the complex conjugate of > the impedance the first antenna has when driven. Also assume no loss in > the connecting line. > > The power delivered to the second antenna is then Pdi * Aem watts. > > The second antenna will radiate a field with power density equal to G2 > times that of an isotropic antenna supplied with the same power, or > > G2 * (Pdi * Aem) / (4 * pi * r^2) > > where r is the distance from the antenna in the direction in which the > gain is measured. > > Combining these to find the ratio of power density of the field radiated > from the second antenna to the power density of the field striking the > first antenna, we get: > > P density ratio = G1 * G2 * (lambda / (4 * pi * r))^2 > > This is the numerical gain you'll see between the field at the location of > the first passive receiver antenna to the field at a distance r from the > second (radiating) passive receiver antenna. A ratio of less than one > represents attenuation rather than gain. The gain in dB is 10 * the base > 10 logarithm of this ratio, with negative results representing > attenuation. That is, > > Overall gain (dB) = 10 * log[base 10](P density ratio) > > Now let's look at a couple of examples. For simplicity, assume that none > of the original field arrives at the detector location; that is, there's a > perfect shield or obstruction between the original field and the detector > (technically, the detector's antenna). It doesn't matter what kind of > antenna is physically connected to the detector for this analysis. In real > life, the detector would probably be a receiver, but I'll call it a > detector so hopefully its antenna won't be confused for either of the two > passive receiver's antennas. > > Let G1 = G2 = 10 -- both antennas comprising the passive repeater have 10 > dBi gain (although don't forget that G1 and G2 are numerical, not dB > gains -- the two numbers just happen to be the same in the case of 10). > Wavelength = 30 meters (10 MHz frequency), and r = 10 meters -- we've put > the detector's antenna 10 meters from the second (radiating) passive > repeater antenna(*). > > Working through the numbers, the power density at the detector's antenna > is 5.7 times, or 7.56 dB greater than, the power density striking the > first antenna. So the signal is stronger than it would have been if we'd > put the detector's antenna right where the first passive repeater antenna > is. Don't forget, though, that it took two 10 dBi antennas to get that > 7.56 dB gain. > > But now let's look at the same setup but at 150 MHz (2 meter wavelength). > The power density at the detector's antenna in this case is just 2.5% of > (or 15.96 dB less than) the power density of the field striking the first > antenna. > > In all cases, if we move the detector's antenna twice as close to the > second (radiating) passive repeater antenna, that is, to 5 meters away, > we'll gain 6 dB; if we double the distance to 20 meters we lose 6 dB. > Before you say, "Aha! let's put the detector antenna 0.000001 meter from > the passive repeater antenna and get incredible gain!" you have to realize > that the antenna gain is achieved only in the far field, so you've got to > keep a good part of a wavelength away for the rules to hold. Actually, 5 > meters is almost certainly too close for the gain to be valid at 10 MHz. > The actual gain at any distance and field strength for a given input power > could easily be determined for a particular antenna by modeling. > > Why does the wavelength make such a big difference? Well, think of the > size of the field each antenna intercepts. Both the 10 MHz and 150 MHz > antennas have the same gain, so the former is dimensionally 15 times > larger than the latter, or 15^2 = 225 times the area. Consquently, the 10 > MHz antenna intercepts 225 times the power that the 150 MHz antenna > does(**). 225 is exactly the ratio between the 10 and 150 MHz results of > 5.7 and 0.025 (if carried out a few more places). > > If you know how much signal strength margin you have at the point where > you put the first passive receiver antenna, you can use the equation above > to calculate how much antenna gain you'll need for your passive repeaters > and how close you'll have to put your receiver's antenna to the second > (radiating) passive receiver antenna, or how to trade the two. Note that > I've assumed perfect match and no loss. If, for example, there's loss in > the transmission line between the two passive repeater antennas, that loss > in dB will directly subtract from the overall passive repeater gain (or > add to the overall passive repeater attenuation). > > (*) 10 meters is only 1/3 wavelengh so a bit close. The nominal antenna > gain might not actually be realized at that short distance. But I'll > assume it is. > > (**) Please don't infer from this that aperture has any obvious > relationship to physical antenna area except in so-called "aperture > antennas" such as horns or parabolic antennas which have large physical > dimensions. The antennas under discussion have apertures proportional to > their physical areas only because they're assumed to be physically > identical except for a scaling factor. In general, antennas with widely > different physical areas can have the same aperture, and antennas with the > same physical area can have widely different apertures. > > Roy Lewallen, W7EL This is way beyond me. Think I'll take up knitting. (if I can get the VSWR right). Regards Mike. Article: 221514 of rec.radio.amateur.antenna From: Roy Lewallen Subject: Re: 160m antenna Date: Tue, 07 Feb 2006 03:57:06 -0800 Message-ID: <11uh2on3uhaf12d@corp.supernews.com> References: Be careful when modeling antennas with offset feed. It's very difficult to prevent common mode current flow on the feedline of offset feed antennas. You might be able to keep the common mode current down to a reasonable level with a couple of good current baluns spaced about a quarter wavelength apart, but otherwise the feedline will be an important part of the antenna and needs to be included in the model. You'll have to include the whole conductive path to the Earth in order to get good accuracy, and this path might not be easy or possible to determine. Roy Lewallen, W7EL jimg wrote: > Hi. I'm looking for more creative ideas. I live in a typical suburban > setting. I have a 100' oak tree out back with a clear base of 65' on > to one side; 75' to the other. I've EZNEC'd a variety of antennas from > center fed (ladder line) inverted vee resonant at about 2.4MHz. Moved > to offset fed versions which works over more bands but still not quite > a low enough swr to load with a palstar balanced tuner on 160. Moved > on to a 'triangle' antenna made by adding a wire base to the inverted > vee about 2-' off the ground. Now I've got enough length, but the swr > is squirrely on all abnds because of the interaction of the short legs > (I guess it's a short delta with only the driven element.). So, it > appears I'll have to wait until the kids graduate and a move to the > countryside is in order. > I know it won't work as well as a wavelength loop with a huge mesh > metal fence counterpoise, but it would be nice to try and ragchew on > 160m while the sunspot cycle is zilch. Any weird topologies come to > mind? And still let me load up 80/40m? > jimg > Oregon > USA Article: 221515 of rec.radio.amateur.antenna From: "Larry Gauthier \(K8UT\)" References: Subject: Re: 160m antenna Message-ID: Date: Tue, 7 Feb 2006 07:09:09 -0500 Jim, Have you thought about going vertical? I'm lucky enough to have room for a 160m dipole, but also have created a shunt-fed 160m vertical from my existing tower. The vertical is barely adequate for "local" QSOs but outperforms the dipole beyond several hundred miles. I also notice that Cushcraft has just released a commercial 160m shortened vertical (30-36 feet). I have not seen any reviews of this antenna yet -- and would generally prefer to build-it-myself -- but there may be some characteristics of the antenna that you could employ. -larry K8UT "jimg" wrote in message news:uujgu1ps47o0olfio3qefelpla3irj7iqe@4ax.com... > Hi. I'm looking for more creative ideas. I live in a typical suburban > setting. I have a 100' oak tree out back with a clear base of 65' on > to one side; 75' to the other. I've EZNEC'd a variety of antennas from > center fed (ladder line) inverted vee resonant at about 2.4MHz. Moved > to offset fed versions which works over more bands but still not quite > a low enough swr to load with a palstar balanced tuner on 160. Moved > on to a 'triangle' antenna made by adding a wire base to the inverted > vee about 2-' off the ground. Now I've got enough length, but the swr > is squirrely on all abnds because of the interaction of the short legs > (I guess it's a short delta with only the driven element.). So, it > appears I'll have to wait until the kids graduate and a move to the > countryside is in order. > I know it won't work as well as a wavelength loop with a huge mesh > metal fence counterpoise, but it would be nice to try and ragchew on > 160m while the sunspot cycle is zilch. Any weird topologies come to > mind? And still let me load up 80/40m? > jimg > Oregon > USA Article: 221517 of rec.radio.amateur.antenna From: "Dr.Ace" Subject: Behringer T1953 Tube Ultragain Mic AMP Processor Date: Tue, 7 Feb 2006 08:18:54 -0500 Message-ID: FA: Behringer T1953 Tube Ultragain Mic AMP Processor http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=7388531285&ssPageName=ADME:L:DS:US:8 Article: 221518 of rec.radio.amateur.antenna From: "Richard Fry" References: <1331-43E81018-167@storefull-3255.bay.webtv.net> Subject: Re: Verticals versus Horizontal Dipoles Date: Tue, 7 Feb 2006 08:00:46 -0600 Message-ID: <43e8a752_3@newsfeed.slurp.net> "Reg Edwards" wrote > Regardless of its noise properties, a quarter-wave and higher vertical > radiates more low-angle power than a half-wave horizontal dipole. _______________ That depends on its r-f ground. Horizontal plane radiation from a 1/4-wave vertical could be worse than the horizontal 1/2-wave dipole if all of the induced ground currents around the vertical aren't collected and returned to the tx/antenna system. And verticals of some heights have zero radiation in the horizontal plane -- one wavelength, for example. RF Article: 221519 of rec.radio.amateur.antenna From: Bob Bob Subject: Re: Verticals versus Horizontal Dipoles References: Message-ID: Date: Tue, 07 Feb 2006 07:48:47 -0600 Tnxs Reg > The angle of the 'horizontal' dipole relative to the horizontal, > whether it is an inverted-V or not, makes negligible difference to the > amount of noise it collects. It is non-critical in this respect. Article: 221520 of rec.radio.amateur.antenna From: Bob Bob Subject: Re: 4nec2 and linux ?? References: <5JydnZ5Siru-FnjenZ2dnUVZ_sednZ2d@comcast.com> <4AydnZv0TsUhJnreSa8jmw@karoo.co.uk> Message-ID: Date: Tue, 07 Feb 2006 08:03:55 -0600 Hi Dan So I have the same GUI interface on both Windoze and Linux boxes Do you know how to launch a *nix shell script from a wine based bat file? Cheers Bob Dan Andersson wrote: > Emulating a NEC for Windooze in Linux?! > > Why are you not running a native NEC - compiled for Linux? Article: 221521 of rec.radio.amateur.antenna From: Bob Miller Subject: Re: unbalance indicator Message-ID: References: <1139317887.027250.80890@f14g2000cwb.googlegroups.com> Date: Tue, 07 Feb 2006 14:53:55 GMT On 7 Feb 2006 05:11:27 -0800, r31dmaeu@unibw.de wrote: >Please give me some suggestions about a device, which can/should >preferably remain online like a SWR meter, which shows the unbalance of >an antenna connected to the station via a balanced feeder. MFJ recently began marketing a device that goes inline on a balanced feedline; a couple of RF ammeters that show the current going through each side of the line. see part mfj-835 bob k5qwg Article: 221522 of rec.radio.amateur.antenna From: chuck Subject: Re: unbalance indicator References: <1139317887.027250.80890@f14g2000cwb.googlegroups.com> <1139325489.747751.319310@g43g2000cwa.googlegroups.com> Message-ID: Date: Tue, 07 Feb 2006 16:20:02 GMT MFJ makes a $99 RF current meter (MFJ-854) which does this and provides 30 ma to 3 amp FS readings. They claim 1 ma is detectable. One milliampere of unbalance is not worth talking about. Gary's do-it-yourself suggestion is a good one. Easy to build and interesting to calibrate. Of course, if the interest is only in determining which of two alternatives creates the greater unbalance, the DIY approach is hard to beat. Both methods will probably require reducing line separation. The MFJ accomodates only 1/2 inch in the clamp. Both methods also leave you with an instrument useful in tracking down RFI problems. Chuck NT3G jgboyles@aol.com wrote: > r31dmaeu@unibw.de wrote: > >>Please give me some suggestions about a device, which can/should >>preferably remain online like a SWR meter, which shows the unbalance of >>an antenna connected to the station via a balanced feeder. > > > To get a relative indication of unbalance on the feeder, run it thru > a toroidal core with a few turns of wire wound around for a secondary > winding. Recitify the secondary voltage, and read with a DC > voltmeter/microamp meter. If you don't have a toroid big enough to fit > around the feeder (likely if you are using >300 ohm line), it should be > ok to transition to smaller line for an inch or so to go through the > toroid. > You are wanting to read the balance of the antenna. The antenna by > itself can be completely balanced, but when you add the transmission > line, the antenna system can become quite unbalanced. The above > detector will give you a relative indication of feeder unbalance, which > I guess you really want to read. > Gary N4AST > Article: 221523 of rec.radio.amateur.antenna From: "Fred W4JLE" References: <1139313678.316393.97290@z14g2000cwz.googlegroups.com> Subject: Re: Why is my car radio acting strangly? Date: Tue, 7 Feb 2006 11:26:14 -0500 Message-ID: <5c10d$43e8ca49$97d56b99$14069@ALLTEL.NET> Have you had your brakes worked on lately? wrote in message news:1139313678.316393.97290@z14g2000cwz.googlegroups.com... > My 1999 Toyota radio has just started acting strangly: the FM seems > fine, but the AM radio is producing a wierd kind of static every time I > drive over a bump. Even a little bump. The "static" sound is similar to > the sound you hear when listening to AM during a storm and there is > lightening nearby. It's quite annoying. > > Is my radio going bad? > Is the antenna connection loose? > Could it have to do with static control (somehow) because of the winter > weather? > > Any advice? > Thanks! > j.wetstein@gmail.com > Article: 221524 of rec.radio.amateur.antenna From: "Christopher Thompson" References: <1139313678.316393.97290@z14g2000cwz.googlegroups.com> <5c10d$43e8ca49$97d56b99$14069@ALLTEL.NET> Subject: Re: Why is my car radio acting strangly? Date: Tue, 7 Feb 2006 11:41:06 -0500 Message-ID: ok the question about brakes is interesting...why ask that one in particular? -- -Chris KF4DRR "Fred W4JLE" wrote in message news:5c10d$43e8ca49$97d56b99$14069@ALLTEL.NET... > Have you had your brakes worked on lately? > > wrote in message > news:1139313678.316393.97290@z14g2000cwz.googlegroups.com... > > My 1999 Toyota radio has just started acting strangly: the FM seems > > fine, but the AM radio is producing a wierd kind of static every time I > > drive over a bump. Even a little bump. The "static" sound is similar to > > the sound you hear when listening to AM during a storm and there is > > lightening nearby. It's quite annoying. > > > > Is my radio going bad? > > Is the antenna connection loose? > > Could it have to do with static control (somehow) because of the winter > > weather? > > > > Any advice? > > Thanks! > > j.wetstein@gmail.com > > > > Article: 221525 of rec.radio.amateur.antenna From: "Fred W4JLE" References: <1139313678.316393.97290@z14g2000cwz.googlegroups.com> <5c10d$43e8ca49$97d56b99$14069@ALLTEL.NET> Subject: Re: Why is my car radio acting strangly? Date: Tue, 7 Feb 2006 11:43:59 -0500 Message-ID: <62d9e$43e8ce72$97d56b99$16795@ALLTEL.NET> Many times when rotors are changed or removed for machining the static spring is left out. Static electricity is built up on the tires and with no path to the body builds up until a bump is hit causing the wheel to bounce up, reducing the gap to the point discharge takes place. "Christopher Thompson" wrote in message news:d60f0$43e8cc34$d8602e79$15284@ALLTEL.NET... > ok the question about brakes is interesting...why ask that one in > particular? > > -- > -Chris > KF4DRR > > > "Fred W4JLE" wrote in message > news:5c10d$43e8ca49$97d56b99$14069@ALLTEL.NET... > > Have you had your brakes worked on lately? > > > > wrote in message > > news:1139313678.316393.97290@z14g2000cwz.googlegroups.com... > > > My 1999 Toyota radio has just started acting strangly: the FM seems > > > fine, but the AM radio is producing a wierd kind of static every time I > > > drive over a bump. Even a little bump. The "static" sound is similar to > > > the sound you hear when listening to AM during a storm and there is > > > lightening nearby. It's quite annoying. > > > > > > Is my radio going bad? > > > Is the antenna connection loose? > > > Could it have to do with static control (somehow) because of the winter > > > weather? > > > > > > Any advice? > > > Thanks! > > > j.wetstein@gmail.com > > > > > > > > > Article: 221526 of rec.radio.amateur.antenna From: "Steve Nosko" Subject: Re: Passive Repeater Date: Tue, 7 Feb 2006 10:16:21 -0600 Message-ID: References: <7_MFf.10650$915.3051@southeast.rr.com> <96okb3-td.ln1@p400bob.personal.cox.net> <11ugs6fc94rabf4@corp.supernews.com> Thanks for the tutorial. The only time I was (remotely) involved in a similar set up was in some very early cell phone demos inside buildings where the cell site was not very close. Two antennas were used, but two sets of filters and amplifiers were used to get considerable power gain in both directions. in/out of the demo room. 73, Steve, K9DCI "Roy Lewallen" wrote in message news:11ugs6fc94rabf4@corp.supernews.com... > I keep hearing about "passive repeaters", but haven't ever seen anything > quantitative about how well they work. I had some measurements done > years ago which showed that a cell phone "passive repeater" in a sedan > doesn't do anything significant, quite obviously because the windows are > such large apertures at that frequency. > > But here are some numbers to work with. Corrections are welcome. > > Assuming perfect efficiency, the maximum effective aperture of an > antenna is Aem = G * lambda^2 / (4 * pi), where > > lambda = the wavelength > G = the antenna's numerical power gain in the direction being analyzed > > The gain in dBi = 10 * log[base10](G). For convenience, use meters for > length dimensions, so the aperture is in square meters and the > wavelength is in meters. > > This means that if we have a field with power density Pdi striking an > antenna with power gain G1 (in the direction the field is coming from), > the antenna can deliver Pdi * Aem watts to a conjugately matched load. > > Now let's connect this antenna to a second antenna with numerical power > gain G2, and assume that the two are perfectly matched to each other. > That is, the input impedance of the second antenna is the complex > conjugate of the impedance the first antenna has when driven. Also > assume no loss in the connecting line. > > The power delivered to the second antenna is then Pdi * Aem watts. > > The second antenna will radiate a field with power density equal to G2 > times that of an isotropic antenna supplied with the same power, or > > G2 * (Pdi * Aem) / (4 * pi * r^2) > > where r is the distance from the antenna in the direction in which the > gain is measured. > > Combining these to find the ratio of power density of the field radiated > from the second antenna to the power density of the field striking the > first antenna, we get: > > P density ratio = G1 * G2 * (lambda / (4 * pi * r))^2 > > This is the numerical gain you'll see between the field at the location > of the first passive receiver antenna to the field at a distance r from > the second (radiating) passive receiver antenna. A ratio of less than > one represents attenuation rather than gain. The gain in dB is 10 * the > base 10 logarithm of this ratio, with negative results representing > attenuation. That is, > > Overall gain (dB) = 10 * log[base 10](P density ratio) > > Now let's look at a couple of examples. For simplicity, assume that none > of the original field arrives at the detector location; that is, there's > a perfect shield or obstruction between the original field and the > detector (technically, the detector's antenna). It doesn't matter what > kind of antenna is physically connected to the detector for this > analysis. In real life, the detector would probably be a receiver, but > I'll call it a detector so hopefully its antenna won't be confused for > either of the two passive receiver's antennas. > > Let G1 = G2 = 10 -- both antennas comprising the passive repeater have > 10 dBi gain (although don't forget that G1 and G2 are numerical, not dB > gains -- the two numbers just happen to be the same in the case of 10). > Wavelength = 30 meters (10 MHz frequency), and r = 10 meters -- we've > put the detector's antenna 10 meters from the second (radiating) passive > repeater antenna(*). > > Working through the numbers, the power density at the detector's antenna > is 5.7 times, or 7.56 dB greater than, the power density striking the > first antenna. So the signal is stronger than it would have been if we'd > put the detector's antenna right where the first passive repeater > antenna is. Don't forget, though, that it took two 10 dBi antennas to > get that 7.56 dB gain. > > But now let's look at the same setup but at 150 MHz (2 meter > wavelength). The power density at the detector's antenna in this case is > just 2.5% of (or 15.96 dB less than) the power density of the field > striking the first antenna. > > In all cases, if we move the detector's antenna twice as close to the > second (radiating) passive repeater antenna, that is, to 5 meters away, > we'll gain 6 dB; if we double the distance to 20 meters we lose 6 dB. > Before you say, "Aha! let's put the detector antenna 0.000001 meter from > the passive repeater antenna and get incredible gain!" you have to > realize that the antenna gain is achieved only in the far field, so > you've got to keep a good part of a wavelength away for the rules to > hold. Actually, 5 meters is almost certainly too close for the gain to > be valid at 10 MHz. The actual gain at any distance and field strength > for a given input power could easily be determined for a particular > antenna by modeling. > > Why does the wavelength make such a big difference? Well, think of the > size of the field each antenna intercepts. Both the 10 MHz and 150 MHz > antennas have the same gain, so the former is dimensionally 15 times > larger than the latter, or 15^2 = 225 times the area. Consquently, the > 10 MHz antenna intercepts 225 times the power that the 150 MHz antenna > does(**). 225 is exactly the ratio between the 10 and 150 MHz results of > 5.7 and 0.025 (if carried out a few more places). > > If you know how much signal strength margin you have at the point where > you put the first passive receiver antenna, you can use the equation > above to calculate how much antenna gain you'll need for your passive > repeaters and how close you'll have to put your receiver's antenna to > the second (radiating) passive receiver antenna, or how to trade the > two. Note that I've assumed perfect match and no loss. If, for example, > there's loss in the transmission line between the two passive repeater > antennas, that loss in dB will directly subtract from the overall > passive repeater gain (or add to the overall passive repeater attenuation). > > (*) 10 meters is only 1/3 wavelengh so a bit close. The nominal antenna > gain might not actually be realized at that short distance. But I'll > assume it is. > > (**) Please don't infer from this that aperture has any obvious > relationship to physical antenna area except in so-called "aperture > antennas" such as horns or parabolic antennas which have large physical > dimensions. The antennas under discussion have apertures proportional to > their physical areas only because they're assumed to be physically > identical except for a scaling factor. In general, antennas with widely > different physical areas can have the same aperture, and antennas with > the same physical area can have widely different apertures. > > Roy Lewallen, W7EL Article: 221527 of rec.radio.amateur.antenna From: "Tom Donaly" Subject: Re: Verticals versus Horizontal Dipoles References: <1138866750.041474.65870@g49g2000cwa.googlegroups.com> <1138961472.184345.67410@g44g2000cwa.googlegroups.com> <11u93rpp6sqo61e@corp.supernews.com> <176au1dd5a0s6nbri5728ml0ql1j1e1l7j@4ax.com> <11uadmer968m2a2@corp.supernews.com> <11ugadllou7lsff@corp.supernews.com> Message-ID: Date: Tue, 07 Feb 2006 16:58:32 GMT Roy Lewallen wrote: > Mike Coslo wrote: > >> Roy Lewallen wrote: >> >>> >>> A step attenuator which is completely adequate for HF and can easily >>> resolve 1 dB can be made from a few cheap slide switches, some PC >>> board material, and a handful of ordinary 5% quarter watt resistors. >>> Detailed instructions can be found in numerous sources, including the >>> Web -- a Google search brought a large number of hits, the first of >>> which was http://www.arrl.org/tis/info/pdf/9506033.pdf. But I'm >>> afraid that this level of homebrewing is beyond the interest if not >>> the ability of the majority of today's amateurs. >> >> >> >> Got it - Thanks, Roy! >> >> - 73 de Mike KB3EIA - > > > You're very welcome. > > The reason for my rather grumpy comment at the end is that I've > recommended countless times for many years that people interested in > evaluating antennas build a simple step attenuator -- an evening > project. It allows you to make direct, quantitative comparisons between > two antennas -- yours or someone else's, as well as calibrate your "S" > meter. But to date, I've never gotten an iota of feedback that a single > person has actually taken the trouble to build one. Rather, they > continue to debate, ad nauseum and without any meaningful data, whether > one antenna is better than the other, or at best quote differences in > "S-units" read from their meters, without the foggiest idea how many dB > it might represent or how different it is from someone else's meter (or > from the same meter on a different band or a different part of the > scale). The conclusion I've reached is that A) Hams would much rather > argue than actually determine the facts, or B) The vast majority are > unable to build a homebrew project consisting of slide switches, circuit > board material, and resistors. I'm afraid both are probably true. > > Maybe you'll be the first to actually build one. If so, please drop me > an email and let me know -- it'll make my day! > > Roy Lewallen, W7EL I built one, on reading your advice, many moons ago. I'm glad I did. Thanks, Roy. 73, Tom Donaly, KA6RUH Article: 221528 of rec.radio.amateur.antenna From: Bob Bob Subject: Re: Passive Repeater References: <7_MFf.10650$915.3051@southeast.rr.com> <96okb3-td.ln1@p400bob.personal.cox.net> Message-ID: <0tumb3-993.ln1@p400bob.personal.cox.net> Date: Tue, 07 Feb 2006 10:36:15 -0600 Hi Bryan It appears as though we have woken some major discussion... Someone may even do the calculation for you! The parabolic dish/grid "focuses" whatever power you start with. This means more power or a higher gain antenna will mean more signal at the far end. The result is additive. The power limitation is a legal one. I dont remember whether it is 1W (30dBm) or 4W (36dBm) EIRP for 802.11/2.4GHz. The term EIRP refers to the power of the focused beam as if it was the same level that would be obtained from a theoretical point source antenna. In simple terms if you take the 4W EIRP and subtract the antenna gain you will get the output maximum allowed at the transmitter. In your case this would be; 36dBm(EIRP) - 24dB(antgain) = 12dBm or about 8mW Keep in mind that you also have to allow for cable loss between the transmitter and antenna. Numbers in the order of 6-12dB are not uncommon so you would have to subtract this as a system loss. A 6dB loss would bring your max transmitter power up to 18dBm or 32mW. Keep in mind that advertising can be confusing. A bigger number on an antenna brochure always seems better than a smaller one, but may be misleading. I dont quite understand you statement about the grid antenna being adjustable in power. (Also note cable loss affects the receiver too so you should try to minimise it) These are pretty low levels and are unlikely to upset any passing birds! I wouldnt however sit in front of the dish for any extended length of time. I'm just paranoid though! re joining the antennas, yes just join the pigtails exactly as you mentioned. Note others comments on the greater effectiveness of a billboard reflector though. I didnt mention this thinking you wanted to keep the visual effect small. I guess you could always disguise it as something else though! The higher the gain of the passive devices the larger the signal that will be relayed. Higher gain means narrower or sharper directivity. The problem is to work out how much you actually need without just trying it and maybe failing. You could equally as well go for a couple of your 24dB grid antennas joined. I should also mention that one of other major importances of a directive antenna is to reduce multipathing or the signal bouncing off objects to the side of the main path and getting to the antenna a little later than the main signal. This can cause problems and slow your link down, may even make it unusable. Oh and speaking of which did you try bouncing the signal off the house? I dont see the antenna mounting (separation) on both sides of the utility pole as being a problem. Also checking. There is a max distance parameter that will need tweaking in a 802.11 setup. Make sure that is set to 2km or so. Cheers Bob Bryan Martin wrote: > The building location is maybe 500 feet away from where the repeater would > be. The parabolic grid is maybe 3000-3500 feet away from the repeater > location. Article: 221529 of rec.radio.amateur.antenna From: "Steve Nosko" Subject: Re: Verticals versus Horizontal Dipoles..OT Date: Tue, 7 Feb 2006 10:39:28 -0600 Message-ID: References: <1138866750.041474.65870@g49g2000cwa.googlegroups.com> <1138961472.184345.67410@g44g2000cwa.googlegroups.com> <11u93rpp6sqo61e@corp.supernews.com> <176au1dd5a0s6nbri5728ml0ql1j1e1l7j@4ax.com> <11uadmer968m2a2@corp.supernews.com> <11ugadllou7lsff@corp.supernews.com> //sympathy flag set// Discussion of technical subjects between some hams can be frustrating to listen to when you are accustomed to a lifetime of technical discussions and experience with a sound understanding of the basics in the field. It is indeed baffling to them, with all the seemingly black magic rules, semi-truths and misconceptions they have heard over the years. Couple this with one or two personal experiences which provide anecdotal "evidence" and you can here some truly interesting interpretations. Some of it is amusing; some is sad and some degrades to childish. A genuine interest is a jewel and when someone expresses this, it is a joy to pass along the knowledge you have gained over the years. Roy, While somewhat experienced in the field, I always enjoy your knowledgeable and clear explanations. Some are informative, some are what I already understand and some serve to affirm what I believe to be true based on some related, but not direct experience. The latter is a joy as it affirms that your (my) basics haven't failed you (me). Thanks, Keep a stiff upper, and all that. //sympathy flag cleared// (:-) 73, Steve, K9DCI Hmmm. Interesting that MSoft Word wants to convert my smiley into some obscure block character...sigh and some of it is difficult to listen to without wanting to join-in and add some correction. "Roy Lewallen" wrote in message news:11ugadllou7lsff@corp.supernews.com... > Mike Coslo wrote: > > Roy Lewallen wrote: > > > >> > >> A step attenuator which is completely adequate for HF and can easily > >> resolve 1 dB can be made from a few cheap slide switches, some PC > >> board material, and a handful of ordinary 5% quarter watt resistors. > >> Detailed instructions can be found in numerous sources, including the > >> Web -- a Google search brought a large number of hits, the first of > >> which was http://www.arrl.org/tis/info/pdf/9506033.pdf. But I'm afraid > >> that this level of homebrewing is beyond the interest if not the > >> ability of the majority of today's amateurs. > > > > > > Got it - Thanks, Roy! > > > > - 73 de Mike KB3EIA - > > You're very welcome. > > The reason for my rather grumpy comment at the end is that I've > recommended countless times for many years that people interested in > evaluating antennas build a simple step attenuator -- an evening > project. It allows you to make direct, quantitative comparisons between > two antennas -- yours or someone else's, as well as calibrate your "S" > meter. But to date, I've never gotten an iota of feedback that a single > person has actually taken the trouble to build one. Rather, they > continue to debate, ad nauseum and without any meaningful data, whether > one antenna is better than the other, or at best quote differences in > "S-units" read from their meters, without the foggiest idea how many dB > it might represent or how different it is from someone else's meter (or > from the same meter on a different band or a different part of the > scale). The conclusion I've reached is that A) Hams would much rather > argue than actually determine the facts, or B) The vast majority are > unable to build a homebrew project consisting of slide switches, circuit > board material, and resistors. I'm afraid both are probably true. > > Maybe you'll be the first to actually build one. If so, please drop me > an email and let me know -- it'll make my day! > > Roy Lewallen, W7EL Article: 221530 of rec.radio.amateur.antenna From: "Steve Nosko" Subject: Re: Rocket Antennas... Date: Tue, 7 Feb 2006 10:58:15 -0600 Message-ID: References: <9asfu1lrtksihlbhvl2ns6kk948apfg02l@4ax.com> wrote in message news:9asfu1lrtksihlbhvl2ns6kk948apfg02l@4ax.com... > I'm helping the SDSU mechanical engineering students with their Rocket. > See: http://www-rohan.sdsu.edu/%7esharring/sdsurocket.html > > I've asked for help on this group before, but the response went over my head. > I a reasonably skilled EE, with ZERO antenna design experience. > I would like to design an antenna that was conformal with the rocket main tube. > The rocket is about 8" in diameter and all metal. > I need two antennas.... > I have two channels a 70cm ATV transmitter and a 900Mhz non-ham telemetry radio. > > For the last attempt: > > Telemetry: I put two 1/4 wave verticals on opposite sides of the rocket fed them with a minicircuits splitter. > This worked well as I got data from lift off to impact. > > ATV Last attempt I just had a single 1/4 wave dipole sticking out one side of the rocket. > As the rocket rolled the signal faded in and out. > > The last time I asked this question I got a response that I could not use because I did not understand it. > > So I'm looking for someone to help that can do the detail design. > > IE provide instructions build a tobe with this pattern on it, hook up coax here and trim this spot to adjust SWR. > I'm perfectly willing to get the fabrication done, but the design is beyond me. > > I realize that I'm asking a lot, but any one that wants to help with the antenna can have a > front row seat in the block house to watch it launch, and some cool video tape ;-) > (The launch will be at the MTA near Mojave, CA) > > Paul (Kl7JG) No takers, but it's only been a day... Antenna on a metal tube... sounds difficult. Body roll confounds the problem. Sounds like your experiments worked. What were the probs? Antenna drag and resulting instabilities? I can only suggest searching on "patch antenna". Then there is a slot antenna, but fabricating this as part of the body without weakening the tube sounds equally difficult...and the dimensions may be all wrong to fit the antenna correctly. If I shift into speculation mode, I'd think about an end-fed antenna which trails, but your "metal" rocket sounds as though the exhaust will be rather hostile compared to an Estes engine. Reminds me of an idea I have always wanted to try on the small model rockets. Namely: A on-board transponder for distance measurement. A 10 Meter one transistor FM receiver feeding a simple 2 meter 1-2 transistor FM, xtal controlled transmitter. High power (100w if needed) 10 M mobile transmits a tone to rocket. Therefore airborne RX and 10M antenna need not be anything great. Rocket transponds tone on 2M FM. 2M antenna do-able on small rocket. Mobile receives tone. Black box (easy hardware) in mobile simply counts a reference freq from time of transmitted tone rising edge to received edge. Suitable accounting of internal delays and choice of reference frequency gives simple, direct readout in feet or whatever units desired. Calibrating the display horizontally on the ground is possible. 73, And good luck, Steve, K9DCI Article: 221531 of rec.radio.amateur.antenna From: "hasan schiers" Subject: Re: Verticals versus Horizontal Dipoles Date: Tue, 7 Feb 2006 11:51:29 -0600 Message-ID: References: <1138866750.041474.65870@g49g2000cwa.googlegroups.com> <1138961472.184345.67410@g44g2000cwa.googlegroups.com> <11u93rpp6sqo61e@corp.supernews.com> <176au1dd5a0s6nbri5728ml0ql1j1e1l7j@4ax.com> <11uadmer968m2a2@corp.supernews.com> <11ugadllou7lsff@corp.supernews.com> Hi Roy, MFJ makes a nice 81 dB step attenuator for a very reasonable price (about $70.00 as I recall) for those who don't want to build. In either case (build or buy), one still has to know how to make good use of it, which to my experience is more demanding than either pocket book or soldering solutions. There are a LOT of neat things one can do with a 2 position switch and a step attenuator. For one thing, a lot of myths can be summarily dismissed (after getting enough data points...another problem that gets lost in the shuffle). One simple measurement on anything sky-wave based is completely meaningless. Things like path-length, time of day, etc. need to be "washed out" or "isolated" in order to come to anything even resembling a meaningful conclusion, and one is likely to arrive and multipe conclusions based on the array of variables one investigates. A step attenuator is an absolute essential for anyone who plays with gain antennas or wants to compare antennas. If expense is an issue, you have provided a great solution, otherwise, the MFJ works rather well for not a lot of money. 73, ...hasan, N0AN "Roy Lewallen" wrote in message news:11ugadllou7lsff@corp.supernews.com... > Mike Coslo wrote: >> Roy Lewallen wrote: >> >>> >>> A step attenuator which is completely adequate for HF and can easily >>> resolve 1 dB can be made from a few cheap slide switches, some PC board >>> material, and a handful of ordinary 5% quarter watt resistors. Detailed >>> instructions can be found in numerous sources, including the Web -- a >>> Google search brought a large number of hits, the first of which was >>> http://www.arrl.org/tis/info/pdf/9506033.pdf. But I'm afraid that this >>> level of homebrewing is beyond the interest if not the ability of the >>> majority of today's amateurs. >> >> >> Got it - Thanks, Roy! >> >> - 73 de Mike KB3EIA - > > You're very welcome. > > The reason for my rather grumpy comment at the end is that I've > recommended countless times for many years that people interested in > evaluating antennas build a simple step attenuator -- an evening project. > It allows you to make direct, quantitative comparisons between two > antennas -- yours or someone else's, as well as calibrate your "S" meter. > But to date, I've never gotten an iota of feedback that a single person > has actually taken the trouble to build one. Rather, they continue to > debate, ad nauseum and without any meaningful data, whether one antenna is > better than the other, or at best quote differences in "S-units" read from > their meters, without the foggiest idea how many dB it might represent or > how different it is from someone else's meter (or from the same meter on a > different band or a different part of the scale). The conclusion I've > reached is that A) Hams would much rather argue than actually determine > the facts, or B) The vast majority are unable to build a homebrew project > consisting of slide switches, circuit board material, and resistors. I'm > afraid both are probably true. > > Maybe you'll be the first to actually build one. If so, please drop me an > email and let me know -- it'll make my day! > > Roy Lewallen, W7EL Article: 221532 of rec.radio.amateur.antenna From: Roy Lewallen Subject: Re: unbalance indicator Date: Tue, 07 Feb 2006 12:05:59 -0800 Message-ID: <11uhvdb83l5434f@corp.supernews.com> References: <1139317887.027250.80890@f14g2000cwb.googlegroups.com> <1139325489.747751.319310@g43g2000cwa.googlegroups.com> jgboyles@aol.com wrote: > r31dmaeu@unibw.de wrote: > >>Please give me some suggestions about a device, which can/should >>preferably remain online like a SWR meter, which shows the unbalance of >>an antenna connected to the station via a balanced feeder. > > > To get a relative indication of unbalance on the feeder, run it thru > a toroidal core with a few turns of wire wound around for a secondary > winding. Recitify the secondary voltage, and read with a DC > voltmeter/microamp meter. If you don't have a toroid big enough to fit > around the feeder (likely if you are using >300 ohm line), it should be > ok to transition to smaller line for an inch or so to go through the > toroid. > You are wanting to read the balance of the antenna. The antenna by > itself can be completely balanced, but when you add the transmission > line, the antenna system can become quite unbalanced. The above > detector will give you a relative indication of feeder unbalance, which > I guess you really want to read. > Gary N4AST > This is the best method. Be sure to run both conductors through the core. The core itself will act as something of a common mode choke (current balun) unless you terminate the winding in a fairly low resistance. Terminating it will reduce its effect on the line you're measuring. I typically use about 10 turns for the secondary with 51 ohms across it. That gives an insertion impedance of 51 / 100 = 0.51 ohm, which is negligible. I prefer to do this so my measuring device doesn't disturb what I'm measuring -- if I want a balun I do it separately. I suggest using a second core/winding on just one of the wires so you can compare the total wire current to the imbalance current. It's very important to terminate the one on the single wire, and if you want to use the two for comparison, you'll then also have to terminate the other. A high-permeability "low frequency" ferrite core is best for these, like Fair-Rite type 70 series (72, 73, 77, etc.). Type 43, a very common type used largely for EMI reduction, is also ok. If you terminate the winding in about 50 ohms, you can put your sensor at a remote location and run 50 ohm coax between the core and detector/termination without disturbing the reading except for the coax loss. I don't recommend two RF ammeters as some others have suggested. They only tell you amplitude and not phase. You can have some pretty seriously imbalanced currents and still see equal meter readings. Roy Lewallen, W7EL Article: 221533 of rec.radio.amateur.antenna From: tclay@qmc.ph.msstate.edu Subject: Re: Antenna analyzer- no MW? Date: 07 Feb 2006 14:42:18 -0600 Message-ID: <87zml2c34l.fsf@qmc.ph.msstate.edu> References: <1139341257.659885.24440@z14g2000cwz.googlegroups.com> >instrument? No demand? Too exotic? >Does anyone know if the analyzer could be modified (add some >inductance, etc. somewhere) to bring it down to about 500kc? Thanks! Another thing to think about: most of the analyzers around are pretty much useless on low freqs anyway due to interference from AM broadcast signals. I recently finished shunt feeding my tower for 160m, and found that my AEA CIA analyzer was completely useless trying to measure the feed impedance. In the end I just used a regular swr meter to adjust the shunt feed. I don't remember exactly how low the AEA goes, but it is below 1.8 MHz. Tor N4OGW/5 Article: 221534 of rec.radio.amateur.antenna From: "F4DRH" References: <1139317887.027250.80890@f14g2000cwb.googlegroups.com> <0eahu1h9ptrq0c95maqn8cj6une95le0vn@4ax.com> Subject: Re: unbalance indicator Date: Tue, 7 Feb 2006 22:43:19 +0100 Message-ID: <43e91475$0$29208$8fcfb975@news.wanadoo.fr> You can see an exemple here: "> A pair of match RF amp meters. > > 73, > Danny > You can see an example here: http://www.barbaxoops.com/modules/xcgal/displayimage.php?pid=47&album=7&pos=1 Regards Jean-Marc F4DRH www.barbaxoops.com Article: 221535 of rec.radio.amateur.antenna From: "me" Subject: Re: Hi Q TAD Question Date: Wed, 8 Feb 2006 07:50:24 +1000 Message-ID: References: Must be at least ONE Hi Q 4/160 TAD in service somewhere to get a comment.. "me" wrote in message news:ds3hd3$p8h$1@news-02.connect.com.au... > Hi I need to hear any comments in rgds the performance of the HI Q TAD > 4/160 (Tune a dipole ) > quality, performance, anything really, ease of tuning, etc etc > > rgds > > Article: 221536 of rec.radio.amateur.antenna From: Roy Lewallen Subject: Re: unbalance indicator Date: Tue, 07 Feb 2006 14:30:15 -0800 Message-ID: <11ui7rrkkcm093a@corp.supernews.com> References: <1139317887.027250.80890@f14g2000cwb.googlegroups.com> <1139325489.747751.319310@g43g2000cwa.googlegroups.com> <11uhvdb83l5434f@corp.supernews.com> Ian White GM3SEK wrote: > > Another option would be to make two identical transformers, one for each > wire, and connect both secondaries to the same terminating resistor. > Reversing one of the secondaries gives true vector addition or > subtraction of the two currents, and then you can detect and measure the > resultant in the normal way. > > Out-of-phase connection of the two secondaries indicates the > differential line current, or the in-phase connection gives the > common-mode current (hopefully much smaller). > > I think that should work... > Excellent idea. But be sure to use a fairly low value of terminating resistor for this and any time you run just one of the conductors through the core. Otherwise you'll be putting a significant impedance in series with your feedline conductor, causing mismatch and/or loss. The insertion impedance, that is, the effective series impedance of the core, will be Rt / N^2, where Rt is the terminating resistor connected across the secondary winding and N is the number of secondary turns. Lower values of terminating resistor will reduce the detector's sensitivity, but this won't be a problem at moderate or even quite low power levels. Roy Lewallen, W7EL Article: 221537 of rec.radio.amateur.antenna From: Roy Lewallen Subject: Re: Antenna analyzer- no MW? Date: Tue, 07 Feb 2006 14:35:28 -0800 Message-ID: <11ui85kbv5qt22a@corp.supernews.com> References: <1139341257.659885.24440@z14g2000cwz.googlegroups.com> <87zml2c34l.fsf@qmc.ph.msstate.edu> tclay@qmc.ph.msstate.edu wrote: > Another thing to think about: most of the analyzers around are pretty > much useless on low freqs anyway due to interference from AM broadcast > signals. > > I recently finished shunt feeding my tower for 160m, and found that > my AEA CIA analyzer was completely useless trying to measure the feed > impedance. In the end I just used a regular swr meter to adjust the > shunt feed. I don't remember exactly how low the AEA goes, but it is > below 1.8 MHz. > > Tor > N4OGW/5 Yes, it's ironic that the one thing "antenna analyzers" are pretty useless for, in an urban environment at least, is analyzing antennas. Some time back I mentioned how a "half wave filter" could be used to reduce out-of-band signals without disturbing the measurement too much. The postings should be possible to locate at groups.google.com. Please read all postings, because I recall incorrectly saying that the filter could be used at frequencies lower (for a lowpass) or higher (for a highpass) frequency than the design frequency. I later corrected that. A given filter is good over only about one HF band without significant disturbance of the measurement. Roy Lewallen, W7EL Article: 221538 of rec.radio.amateur.antenna From: Jack O'Neill Subject: Re: Why is my car radio acting strangly? References: <1139313678.316393.97290@z14g2000cwz.googlegroups.com> Message-ID: <6h9Gf.12173$tq.2745@fe10.lga> Date: Tue, 07 Feb 2006 17:36:01 -0500 This is a multi-part message in MIME format. --------------060303040608030605090007 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit j.wetstein@gmail.com wrote: >My 1999 Toyota radio has just started acting strangly: the FM seems >fine, but the AM radio is producing a wierd kind of static every time I >drive over a bump. Even a little bump. The "static" sound is similar to >the sound you hear when listening to AM during a storm and there is >lightening nearby. It's quite annoying. > >Is my radio going bad? >Is the antenna connection loose? >Could it have to do with static control (somehow) because of the winter >weather? > >Any advice? >Thanks! >j.wetstein@gmail.com > > > check the antenna connections. This happened to me a while ago. 73 --------------060303040608030605090007 Content-Type: text/html; charset=us-ascii Content-Transfer-Encoding: 7bit j.wetstein@gmail.com wrote:
My 1999 Toyota radio has just started acting strangly: the FM seems
fine, but the AM radio is producing a wierd kind of static every time I
drive over a bump. Even a little bump. The "static" sound is similar to
the sound you hear when listening to AM during a storm and there is
lightening nearby. It's quite annoying.

Is my radio going bad?
Is the antenna connection loose?
Could it have to do with static control (somehow) because of the winter
weather?

Any advice? 
Thanks!
j.wetstein@gmail.com

  
check the antenna connections.  This happened to me a while ago.
73
--------------060303040608030605090007-- Article: 221539 of rec.radio.amateur.antenna From: "Gary Smith" Subject: Re: Why is my car radio acting strangly? Date: Tue, 7 Feb 2006 23:31:30 +1100 Message-ID: References: <1139313678.316393.97290@z14g2000cwz.googlegroups.com> Sounds like a loose wire or something scraping metal on or near one section of the whole radio/antenna setup. if you grab a piece of wire and scratch it back and forth on the radio case (metal) you will get the same effect. Start looking for loose connections/case/wires under dash etc. gary wrote in message news:1139313678.316393.97290@z14g2000cwz.googlegroups.com... > My 1999 Toyota radio has just started acting strangly: the FM seems > fine, but the AM radio is producing a wierd kind of static every time I > drive over a bump. Even a little bump. The "static" sound is similar to > the sound you hear when listening to AM during a storm and there is > lightening nearby. It's quite annoying. > > Is my radio going bad? > Is the antenna connection loose? > Could it have to do with static control (somehow) because of the winter > weather? > > Any advice? > Thanks! > j.wetstein@gmail.com > Article: 221540 of rec.radio.amateur.antenna From: rgawtry@timewave.com (Randall Gawtry) Subject: Re: Antenna analyzer- no MW? Date: Wed, 08 Feb 2006 03:07:48 GMT Message-ID: <11uio45s728gga4@corp.supernews.com> References: <1139341257.659885.24440@z14g2000cwz.googlegroups.com> In article <1139341257.659885.24440@z14g2000cwz.googlegroups.com>, "chris" wrote: >I've been thinking about springing for an MFJ (or other) antenna >analyzer >to check on the myriad antenna's I've got around the place. >I noticed that most of the analyzers on the market (like the MFJ-269, >for ~$350.00) >only go down to 1.8 MHz. I do a lot of work with xtal radio's >(DX'ing), and have a lot of different AM (MW) antenna's strewn about >the property. I was wondering why they cut that portion out of their >instrument? No demand? Too exotic? >Does anyone know if the analyzer could be modified (add some >inductance, etc. somewhere) to bring it down to about 500kc? Thanks! >Chris, AI4MI > take a look at: http://www.timewave.com/TZ-900.html Randy, K0CBH Timewave Article: 221541 of rec.radio.amateur.antenna From: "hasan schiers" Subject: Re: Why did this work (160m antenna)? Date: Wed, 1 Feb 2006 15:04:57 -0600 Message-ID: References: Hi Chuck, The lawn staples are from DX Engineering (as was the beautiful radial plate with bulkhead coax connector). They are about 6 inches long, a rectangle, maybe 1 inch wide, and heavy enough that you can pound them in with a hammer, as long as your soil isn't concrete. Sold in packages of 10 or 20, I think. Quite reasonably priced. I only have one staple per wire now (doing it in the middle of winter made me move quickly between ice and mud patches). I'll put down a staple every 10' or so when things dry out. Google DX Engineering and you will find there web site. From there it's pretty easy to find stuff. 73, ...hasan, N0AN Article: 221542 of rec.radio.amateur.antenna From: "Bryan Martin" Subject: 802.11 link Message-ID: Date: Wed, 01 Feb 2006 21:25:48 GMT I am attempting to setup a 802.11b bridge between my location (siteA) down the powerlines but off to the right NLOS (siteB) roughly 1 mile away. Now their is nothing between the powerline and siteB except it is off the powerlines to the right by about 20-40 feet. No trees, hills or any other unforeseen obstacles other than I simply cant see it due to the location. I guess the easy way to explain the setup is picture a L. I have successfully been able to broadcast my signal in reverse from siteA down the powerline even further than siteB but it was a strait shot and also was NLOS due to a house being directly in front. This was using a 24db parabolic grid antenna. My question and what I am trying to get my head around is if I could get by with just a standard wireless router without any external addon or booster antenna at siteB. Common sense tells me that even though its shaped similar to a L as long as the signal coming off siteB is present at the end of the powerline then I should be able to pick it up from the grid antenna. I plan on trying it this weekend but I am hoping someone can elaborate on this before I get my hopes up to much. -- Poor planning on your part does not constitute an emergency on my part. Article: 221543 of rec.radio.amateur.antenna From: "gianluca" <9a6nfg@hamradio.hr> Subject: folded dipole Date: Wed, 8 Feb 2006 12:48:23 +0100 Message-ID: hy to all ! where can i find a link with the plan how to make a folded dipol for 80 meter band my problem is not to much place on my roof, thank you 73 9a6nfg JN65TC Luca Article: 221544 of rec.radio.amateur.antenna From: "Dale Parfitt" References: Subject: Re: folded dipole Message-ID: Date: Wed, 08 Feb 2006 13:46:00 GMT "gianluca" <9a6nfg@hamradio.hr> wrote in message news:dsclq6$ies$1@bagan.srce.hr... > hy to all ! where can i find a link with the plan how to make a folded > dipol for 80 meter band my problem is not to much place on my roof, thank > you 73 9a6nfg JN65TC Luca > >A folded dipole is the same length as a classic wire dipole. The folded >term relates to the two parallel conductors not the overall length.. Dale W4OP Article: 221545 of rec.radio.amateur.antenna From: chuck Subject: Re: Lightning Arrestor Questions References: <12633-43CE9762-1365@storefull-3254.bay.webtv.net> Message-ID: Date: Wed, 08 Feb 2006 19:44:26 GMT Peak current of 100,000 A for 1 microsecond in wire with resistance of (say) one ohm gives energy of 10,000 Joule. If the wire is No. 12, that would warm it up pretty well, but vaporize? Where have I gone astray? TIA Chuck Article: 221546 of rec.radio.amateur.antenna From: "Jeff Dieterle" Subject: Another Car Radio static question Date: Thu, 9 Feb 2006 09:17:26 -0500 Message-ID: <10cd5$43eb4ef3$424980b2$32629@COMTECK.COM> I drive the same route everyday. On the same 1.5 mile section I get a very loud buzz and on top of the buzz a higher pitched periodic hum lasting for 10 seconds and occurring every 30 seconds overpowering everything on the low end of the am band. There is a 3-phase distribution line along the road, would a failing insulator create this type of problem, I thought that would be more localized than covering a 1.5 mile stretch. Along this 1.5 miles I travel 3 different directions and the intensity doesn't change much and it doesn't make any difference what time of night or day. Near one end of this area, there is a transmission tower of some type. The tower has been there long before cell phone towers started sprouting like weeds, also it doesn't have the dish array near the top just a straight tower, probably 15' sq. at the base and 75' tall. Is the person or company responsible for creating this type of interference obligated to correct the cause? Article: 221547 of rec.radio.amateur.antenna From: richardharrison@webtv.net (Richard Harrison) Subject: Re: folded dipole Date: Thu, 9 Feb 2006 11:09:54 -0600 Message-ID: <22778-43EB7762-218@storefull-3258.bay.webtv.net> References: Dale, W4OP wrote: "A folded dipole is the same length as a classic wire dipole. The folded term relates to two parallel conductors not the overall length." true. A 1/2-wave folded dipole has the same radiation pattern as a straight dipole. Its feedpoint resistance is higher, depending on the number of conductors in the dipole and their relative sizes. Another difference is more significant. The folded dipole is also resonant when it has two wires and it is only 1/4-wave long. It is resonant because its circumference is then 1/2 wavelength. The feedpoint resistance of the resonant 1/4-wave long center-fed folded dipole made from the same diameter wire all the way around is 6000 ohms. Special matching may be needed, However, gain is only 1/2-dB less than a 1/2-wave dipole and its radiation pattern is almost the same. Its bandwidth is only 5% of its center frequency while the bandwidth of the 1/2-wave folded dipole is 45% of its center frequency. Bandwidth of the thin single-wire center-fed dipole is 34%. Arnold B. Bailey is the source of this information in "TV and Other Receiving Antennas". Best regards, Richard Harrison, KB5WZI Article: 221548 of rec.radio.amateur.antenna From: richardharrison@webtv.net (Richard Harrison) Subject: Re: Another Car Radio static question Date: Thu, 9 Feb 2006 11:59:15 -0600 Message-ID: <22778-43EB82F3-225@storefull-3258.bay.webtv.net> References: <10cd5$43eb4ef3$424980b2$32629@COMTECK.COM> Jeff Dieterle wrote: "Is the person or company responsible for creating this type of interference obliged to correct the cause?" Maybe. I doubt that leaky insulator noise generates the interference described. It would not likely last for only 10 seconds with a 30-second repetition rate. Such an interference with different duration and repetition from Jeff`s used to plague my company at Houma, Louisiana. Our offshore division for the Gulf of Mexico was stationed at the Houma Airport. It turned out to be caused by the U.S. Government`s radar. Every time it swept our way, it broke the noise-squelch we used on our FM receivers, giving them a click and a buzz. We all wanted to fly safely so we never complained. Best regards, Richard Harrison, KB5WZI Article: 221549 of rec.radio.amateur.antenna From: dplatt@radagast.org (Dave Platt) Subject: Re: Another Car Radio static question Date: Thu, 09 Feb 2006 19:30:36 -0000 Message-ID: <11un62s35hpkk9c@corp.supernews.com> References: <10cd5$43eb4ef3$424980b2$32629@COMTECK.COM> In article <10cd5$43eb4ef3$424980b2$32629@COMTECK.COM>, Jeff Dieterle wrote: >Is the person or company responsible for creating this type of interference >obligated to correct the cause? It depends. If they're radiating RF in excess of FCC part 15 limits, and do not have a license to transmit in whatever frequency band they are using, then they're very probably obligated to fix the problem or to shut down whatever equipment is radiating. If they're transmitting in a frequency band / allocation for which they have a proper license, and if their transmission isn't leaking spurious frequencies in excess of the FCC limits, then they're probably quite legal. In this situation, what you'd hearing would be considered to be "undesired reception" - that is, your car radio is being overwhelmed by a strong signal outside of its normal passband - and the FCC would consider this the fault of your radio. Without doing some spectrum analysis and direction finding it's hard to distinguish the two from the symptoms you report. -- 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: 221550 of rec.radio.amateur.antenna From: richardharrison@webtv.net (Richard Harrison) Subject: Re: Passive Repeater Date: Thu, 9 Feb 2006 14:29:23 -0600 Message-ID: <7814-43EBA623-210@storefull-3257.bay.webtv.net> References: Hal Rosser wrote: "(one acts like a receiver, and the other acts like a transmitter.)" Back-to-back antennas both act like transmitters. Neither cares if its energy came from radiation sweeping it or fed to it from its feedline. The most energy any antenna can extract from a passing wave is 50%. That is only when the receiving antenna is perfectly matched to its load. In this case the load is an identical antenna, so the chances for a match are good. But, at least 50% of the energy captured by the receiving antenna is going to be reradiated by that antenna right back in the direction it came from. Another problem is the rapid decline with distance in the first wavelength from the antenna. It losses 22 dB in field strength in the first wavelength from the transmitting antenna. After traveling through a second wavelength from the antenna (distance doubled from the antenna) the field strength declines by another 6 dB. It loses 6 dB every time the distance doubles. So, after 4 wavelengths, total loss will be 34 dB. At great distances form the transmitting antenna, double the distance is such a great distance that the field strength hardly varies at all even when traveling directly toward or away from the transmitter. It is obvious that path loss is a function of frequency and distance if only from continuous expansion of the sphere of the electromagnetic wavefront. There are less watts per square meter when the watts are the same but the number of square meters is growing. Our initial loss distance was determined by wavelength which is inversely related to the frequency. Best regards, Richard Harrison, KB5WZI Article: 221551 of rec.radio.amateur.antenna From: Steve Silverwood Subject: Re: Any experience with the G5RV multiband wire antenna? Message-ID: References: <184c4$43c1dc66$42a1bfc2$11376@FUSE.NET> Date: Thu, 09 Feb 2006 22:19:44 GMT In article <184c4$43c1dc66$42a1bfc2$11376@FUSE.NET>, jawod@fuse.net says... > The G5RV antenna can be found by googling. Anyone using this > arrangement. It uses a coax feed to balanced feed (which variously acts > as radiating elements, depending on the band). The author says a balun > is not needed but then describes an RF choke that sounds a lot like a > balun. I am also concerned about TVI with this system. I've been using a "shorty" version of the G5RV (not the full length version, due to space limitations -- mine is capable of operating on 40- 10 meters) with moderate success, even at QRP power levels. Rig is an FT-817 with no amplifier, so max power is five watts, often quite a bit lower. -- -- //Steve// Steve Silverwood, KB6OJS Fountain Valley, CA Email: kb6ojs@arrl.net Article: 221552 of rec.radio.amateur.antenna From: Roy Lewallen Subject: Re: Passive Repeater Date: Thu, 09 Feb 2006 15:07:32 -0800 Message-ID: <11uniplf3lgjd4f@corp.supernews.com> References: <7814-43EBA623-210@storefull-3257.bay.webtv.net> Richard Harrison wrote: > . . . > The most energy any antenna can extract from a passing wave is 50%. That > is only when the receiving antenna is perfectly matched to its load. In > this case the load is an identical antenna, so the chances for a match > are good. But, at least 50% of the energy captured by the receiving > antenna is going to be reradiated by that antenna right back in the > direction it came from. > . . . This is a bit misleading. Typically, an antenna extracts only a tiny fraction of the energy from a passing wave. The actual amount of energy it does extract is expressed as its "capture area" or "effective aperture". A recent posting I made includes a way to calculate this if you know the antenna's gain. Because the "capture area" is usually a tiny fraction of the wave's total area, only a tiny fraction of the wave's energy is extracted. Roy Lewallen, W7EL Article: 221553 of rec.radio.amateur.antenna From: "Frank" References: <1139397544.853779.192670@g43g2000cwa.googlegroups.com> Subject: Re: 4nec2 on Windows-XP ? Message-ID: Date: Thu, 09 Feb 2006 23:24:32 GMT Arie, I have done some preliminary tests with 4nec2 on Windows-XP. I have not noticed any particular problems so far, apart from the fragmentation of the GH card -- as also noted by Dan. I would like to run NEC 4 on your software, but cannot seem to find any reference to "4nec4" on the website. I tend to have a bias towards GNEC, but I particularly like your Smith Chart graphic. Whatever, I am sure the graphics are easily better than the basic NEC 4. Frank "Arie" <4nec2@gmx.net> wrote in message news:1139397544.853779.192670@g43g2000cwa.googlegroups.com... > Hello..., > > I would very much like to hear about users who did or did not succeed > running the latest 4nec2 version (5.6.0) on windows-XP. > > This because some now and then I get 'strange' problem-reports for > problems which I am not able to reproduce on the XP systems I have > overhere. I would very much like to tackle this problem, so any > information about this is very welcome. > > Thanks in advance, > Arie. > Article: 221554 of rec.radio.amateur.antenna From: "PA3HGT" Subject: ZM30 analyzer Date: Fri, 10 Feb 2006 00:29:22 +0100 Message-ID: <4521ifF4l1njU1@individual.net> Hello, I purchased a Palstar ZM30 antenna-analyzer recently and i want to measure a trap of W3DZZ dipool (Fritzel W3-2000). I want to measure resonance of the trap , i know the trap is 100% ok and i disassembled from the antenna. I did trying it by the book but no succes ! Has anyone some experience with this analyzer to measure such things ? -- Met vriendelijke groet, Hans Pluijgers Hamcall: PA3HGT www.pa3hgt.nl Article: 221555 of rec.radio.amateur.antenna From: "Reg Edwards" Subject: Re: Any experience with the G5RV multiband wire antenna? Date: Thu, 9 Feb 2006 23:46:31 +0000 (UTC) Message-ID: References: <184c4$43c1dc66$42a1bfc2$11376@FUSE.NET> There's more nonsense, old wives tales and gobbledegook generated by THAT antenna than all other antennas put together. Just erect the longest and highest dipole you have space for and feed it with 450-ohm open-wire line all the way to the shack. If you don't have a balanced tuner, use an unbalanced tuner with a choke balun. An unbalanced tuner will probably be better anyway. To lengthen a dipole make an inverted-U. Or make a Z with it. ---- Reg. Article: 221556 of rec.radio.amateur.antenna From: Owen Duffy Subject: Re: Another Car Radio static question Message-ID: References: <10cd5$43eb4ef3$424980b2$32629@COMTECK.COM> <11un62s35hpkk9c@corp.supernews.com> Date: Fri, 10 Feb 2006 00:32:54 GMT On Thu, 09 Feb 2006 19:30:36 -0000, dplatt@radagast.org (Dave Platt) wrote: >In article <10cd5$43eb4ef3$424980b2$32629@COMTECK.COM>, >Jeff Dieterle wrote: > >>Is the person or company responsible for creating this type of interference >>obligated to correct the cause? > >It depends. > >If they're radiating RF in excess of FCC part 15 limits, and do not >have a license to transmit in whatever frequency band they are using, >then they're very probably obligated to fix the problem or to shut >down whatever equipment is radiating. Though if they call it BPL, they will probably get a free ride! Owen -- Article: 221557 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: folded dipole References: <22778-43EB7762-218@storefull-3258.bay.webtv.net> Message-ID: Date: Fri, 10 Feb 2006 00:59:10 GMT Richard Harrison wrote: > The folded dipole is also resonant when > it has two wires and it is only 1/4-wave long. It is resonant because > its circumference is then 1/2 wavelength. > The feedpoint resistance of the resonant 1/4-wave long center-fed folded > dipole made from the same diameter wire all the way around is 6000 ohms. Richard, that doesn't make sense to me. Such an antenna could be fed with 1/4WL of 600 ohm open-wire line and achieve an impedance of 60 ohms looking into the matching section. That's just too good to be true. I just ran an 80m folded dipole on 160m using EZNEC. It says the feedpoint impedance is 32+j1900 ohms. That's a long way from resonance and 6000 ohms. -- 73, Cecil http://www.qsl.net/w5dxp Article: 221558 of rec.radio.amateur.antenna From: "David Thompson" References: Subject: Re: More info on old Tower Message-ID: Date: Fri, 10 Feb 2006 04:29:29 GMT Chris, I can't see the drawing but Wilson made several models of self supporting tubular masts. These are now sold by US Tower as the MA-40, 55, and 70. They have a rotating base option. Dave K4JRB "Chris W" <1qazse4@cox.net> wrote in message news:jBYDf.9$8D6.1@dukeread11... > I have acquired an old tower. I was told the brand is Wilson but I > can't seem to find any information on it. I have photos and I 3D model > I drew here.... > http://cdw.homelinux.com:8087/stuff/Tower/ > > If some one could tell me where I can find specs on it and what kind of > wind load it can handle, I would be grateful. > > Note you have to down load this free program to view the 3D model > > http://www.alibre.com/products/addons/modelpress.asp > > -- > Chris W > KE5GIX > > Gift Giving Made Easy > Get the gifts you want & > give the gifts they want > One stop wish list for any gift, > from anywhere, for any occasion! > http://thewishzone.com Article: 221559 of rec.radio.amateur.antenna From: "Hal Rosser" References: <1139313678.316393.97290@z14g2000cwz.googlegroups.com> Subject: Re: Why is my car radio acting strangly? Message-ID: <_aVGf.2059$UD1.320@bignews2.bellsouth.net> Date: Fri, 10 Feb 2006 00:08:57 -0500 > > Is my radio going bad? > Is the antenna connection loose? > Could it have to do with static control (somehow) because of the winter > weather? > > Any advice? > Thanks! > j.wetstein@gmail.com When my car radio had that problem, I FINALLY fixed it by running an extra wire from the negative side of the battery to the car's body. It was hard to trace an intermittent ground. I gave the ole multimeter a good workout that day. Article: 221560 of rec.radio.amateur.antenna From: "PA3HGT" Subject: Re: ZM30 analyzer Date: Fri, 10 Feb 2006 11:47:22 +0100 Message-ID: <45399mF46dqfU1@individual.net> References: <4521ifF4l1njU1@individual.net> <43EBF233.2080403@comcast.net> The trap is a coil and a capacitor in parrallel. The antenna is for 40 and 80 meters and the trap works in the 40 mtr band. >From the feedingpoint to the trap is 2 times 10 mtrs (for 40 mtr) and then some 7 mtrs for 80mtrs. When you work on 40 , the antenna works only from the feedingpoint to the trap because the circuit "cut" the antenna so you work then with 2 times 10 mtrs. The manual says that traps can be measured,i tried by manual but no luck. -- Met vriendelijke groet, Hans Pluijgers Hamcall: PA3HGT www.pa3hgt.nl >I am not familiar with this antenna. Is this a pass > filter? If so it will not have a resonant frequency. It > will have a cut off point. The tool for that would be a > spectrum analyzer and a tracking generator. > > > PA3HGT wrote: >> Hello, >> >> I purchased a Palstar ZM30 antenna-analyzer recently and >> i want to measure a trap of W3DZZ dipool (Fritzel >> W3-2000). I want to measure resonance of the trap , i know the >> trap is 100% ok and i disassembled from the antenna. >> I did trying it by the book but no succes ! >> Has anyone some experience with this analyzer to measure >> such things ? Article: 221561 of rec.radio.amateur.antenna From: "Christopher Thompson" References: <1139313678.316393.97290@z14g2000cwz.googlegroups.com> <_aVGf.2059$UD1.320@bignews2.bellsouth.net> Subject: Re: Why is my car radio acting strangly? Date: Fri, 10 Feb 2006 08:52:11 -0500 Message-ID: <91015$43ec991b$d8602e79$2545@ALLTEL.NET> that raises a good question. had there been any engine work where they may have inadvertantly left the ground strap from the body to the engine off or loose? keep in mind as posted below the body is grounded to the engine block, and the battery neg goes to the engine block. -- -Chris KF4DRR "Hal Rosser" wrote in message news:_aVGf.2059$UD1.320@bignews2.bellsouth.net... > > > > Is my radio going bad? > > Is the antenna connection loose? > > Could it have to do with static control (somehow) because of the winter > > weather? > > > > Any advice? > > Thanks! > > j.wetstein@gmail.com > > When my car radio had that problem, I FINALLY fixed it by running an extra > wire from the negative side of the battery to the car's body. It was hard to > trace an intermittent ground. I gave the ole multimeter a good workout that > day. > > > Article: 221562 of rec.radio.amateur.antenna From: "J. Mc Laughlin" Subject: Re: Passive Repeater Date: Fri, 10 Feb 2006 09:03:17 -0500 Message-ID: <11up75b1jd998de@corp.supernews.com> References: <9fSFf.10664$915.8953@southeast.rr.com> <7443-43E80747-546@storefull-3257.bay.webtv.net> An example of what Richard is saying is found when listening to a none-too-strong FM broadcast station: if a big airplane flies into the path near either end of the path, one will notice significant vector addition of signals (heard as flutter). Billboard (reflector) type passive reflectors have several applications. One is to place the reflector on a high edge of a ridge that is not accessible part of the year (or that does not have electric power) so as to facilitate propagation along a valley. "Passive Repeater" is used in about three ways: (1) large reflector; (2) back to back connected, gain antennas; and (3) back to back connected antennas with filter and gain blocks in the connection (sometimes, bi-directional). 73 Mac N8TT -- J. Mc Laughlin; Michigan U.S.A. Home: JCM@Power-Net.Net "Richard Harrison" wrote in message news:7443-43E80747-546@storefull-3257.bay.webtv.net... > Bryan Martin wrote: > "Was this supposed to help or was it just a slam?" > > No, my response was factual, neumeric, and specific. It was not meant as > a slam. Reflectors are less lossy than back-to-back antennas. If you are > using microwaves, the size of the reflector may be practical. > > The peflector in the path is most effective when placed near either end > of the path. The reflector can also produce gain over that produced by > the antennas at the path ends. It must be slightly concave to do so. > Commercial reflectors often come equipped with an adjustment to suck in > the center of the reflector for maximum gain once alignment of the > dishes is accomplished. This isn`t speculation. I`ve designed the paths > and performed the adjustments with my own hands. > > Best regatds, Richard Harrison, KB5WZI > Article: 221563 of rec.radio.amateur.antenna From: "J. Mc Laughlin" Subject: Re: Anti-oxidant grease question Date: Fri, 10 Feb 2006 09:10:12 -0500 Message-ID: <11up7id72jhuv5b@corp.supernews.com> References: I am a big fan of Penetrox-A. It is sold in a small squeeze-bottle that is just right for most tasks. It is also a good anti-galling material to use when screwing SS to anything. 73 Mac N8TT -- J. Mc Laughlin; Michigan U.S.A. Home: JCM@Power-Net.Net "John Popelish" wrote in message news:GaKdnbJSoIPeqHveRVn-hQ@adelphia.com... > Joe S. wrote: > (snip) > > I have found a source of anti-oxidant grease that's used on electrical > > connections and I will put this stuff on the connector-mount junction to > > prevent further oxidation. Here's the question: Do I loosen the nut and > > put grease between the nut and the antenna mount -- similar to putting > > thermal grease between a heat sink and the surface of a transistor -- or, do > > I tighten the nut and smear grease on the outside, not on the mating > > surfaces? I suspect I should put the grease on the mating surfaces between > > the nut and the mount -- loosen the nut, smear on grease, tighten the nut. > > The anytioxidant has to be in intimate contact with the metal surfaces > before they are clamped together. Here is a site that tells how to > use one version, Penetrox-A. The details are about 1/4 of the way down: > http://www.inspect-ny.com/aluminum/alreduce.htm#1A Article: 221564 of rec.radio.amateur.antenna From: John Ferrell Subject: Re: More info on old Tower Message-ID: References: Date: Fri, 10 Feb 2006 14:30:04 GMT This is not one of the Wilson MA series. I have the CT-70 that I bought about 1979. The top section failed in a twisting mode back in the mid 80's. I have kept up with maintenance and it is currently installed on a free standing fixture with an electric boat winch to raise & lower it. It spends most of the time at about 30 feet where it is very robust even with a Cushcraft A3S installed. On the list of things to do is the matter of a power tilt winch. I am not as robust as I once was! BTW, it was about $450 when I bought it. On Fri, 10 Feb 2006 04:29:29 GMT, "David Thompson" wrote: >Chris, > >I can't see the drawing but Wilson made several models of self supporting >tubular masts. These are now sold by US Tower as the MA-40, 55, and 70. >They have a rotating base option. >Dave K4JRB > >"Chris W" <1qazse4@cox.net> wrote in message >news:jBYDf.9$8D6.1@dukeread11... >> I have acquired an old tower. I was told the brand is Wilson but I >> can't seem to find any information on it. I have photos and I 3D model >> I drew here.... >> http://cdw.homelinux.com:8087/stuff/Tower/ >> >> If some one could tell me where I can find specs on it and what kind of >> wind load it can handle, I would be grateful. >> >> Note you have to down load this free program to view the 3D model >> >> http://www.alibre.com/products/addons/modelpress.asp >> >> -- >> Chris W >> KE5GIX >> >> Gift Giving Made Easy >> Get the gifts you want & >> give the gifts they want >> One stop wish list for any gift, >> from anywhere, for any occasion! >> http://thewishzone.com > John Ferrell W8CCW Article: 221565 of rec.radio.amateur.antenna From: "John, N9JG" References: <11up7id72jhuv5b@corp.supernews.com> Subject: Re: Anti-oxidant grease question Message-ID: Date: Fri, 10 Feb 2006 15:53:06 GMT Another product that works very well is Lawson 59933 Copper Anti-Seize Anti-Corrosion Compound http://webapp.lawsonproducts.com/website/showItem?itemNum=59933 This is the same product that comes with a Butternut vertical antenna. It consists of a synthetic grease base, copper, thickener, and rust inhibitor. It can withstand temperature ranges from -65°F to 1800°F, which should be adequate for most ham applications. John, N9JG "J. Mc Laughlin" wrote in message news:11up7id72jhuv5b@corp.supernews.com... >I am a big fan of Penetrox-A. It is sold in a small squeeze-bottle that is > just right for most tasks. It is also a good anti-galling material to use > when screwing SS to anything. Article: 221566 of rec.radio.amateur.antenna From: richardharrison@webtv.net (Richard Harrison) Subject: Re: folded dipole Date: Fri, 10 Feb 2006 09:52:17 -0600 Message-ID: <7289-43ECB6B1-96@storefull-3251.bay.webtv.net> References: Cecil, W5DXP wrote: "Such an antenna could be fed with 1/4 WL of 600 ohm open wire line and achieve an impedance of 60 ohms looking into the matching section." Exactly. The actual impedance of the 1/4-wave folded dipole is an inverse function of the wire diameter. It can be chosen to present 6000 ohms. Arnold B. Bailey has studied the behavior, developed the formulas, and published graphs for the user to choose wire sizes for folded dipoles of either 1/4-wave or 1/2-wave overall length. He does a sample calculation and showes his work for one particular 1/4-wave folded dipole. On page 414 of "TV and Other Receiving Antennas" Bailey writes: "At first resonance (where the total wire length is 1/2-wave and overall length is 1/4-wave), the current in the continuous rod (entire wire length) approaches a constant value, varying from a maximum in the center (farthest from the drivepoint) to about 0.7 of maximum at the ends. For this reason the radiation resistance RR approaches the value for a constant-current rod. The practical value is approximately RR=570(l squared), where l is the nominal over-all length and equals 0,25 wavelength, thus resulting in a value of 35.6 ohms." The 1/4-wave folded dipole shares some of the characteristics of a short-circuited stub. It is a resonant circuit element which converts the low impedance at its short-circuit into a high impedance at its feedpoint. If the 1/4-wave folded dipole is a little short of 1/2-wave around its perimeter, it presents an inductive reactance. If a little longer electrically than 1/2-wave around, it presents a capacitive reactance. Best regards, Richard Harrison, KB5WZI Article: 221567 of rec.radio.amateur.antenna From: "kd5sak" References: <1139596215.876386.165400@g44g2000cwa.googlegroups.com> Subject: Re: Some info needed!? Message-ID: Date: Fri, 10 Feb 2006 19:15:29 GMT "ceaser" wrote in message news:1139596215.876386.165400@g44g2000cwa.googlegroups.com... >I have gotten a GE 40 channel handheld CB is there anything I can do to > this that would go beyoind the normal operating range? thanks The only legal method would be a good directional (beam) antenna on a high tower. Harold Article: 221568 of rec.radio.amateur.antenna From: Bob Bob Subject: Re: Some info needed!? References: <1139596215.876386.165400@g44g2000cwa.googlegroups.com> Message-ID: Date: Fri, 10 Feb 2006 13:29:50 -0600 Legally? A bigger/higher antenna.. Many handlhelds have places to plug in an external antenna. Stand on a hill top to use it. Cheers Bob ceaser wrote: > > I have gotten a GE 40 channel handheld CB is there anything I can do to > this that would go beyoind the normal operating range? thanks > Article: 221569 of rec.radio.amateur.antenna From: "kevin" Subject: help appreciated with unusual j pole feed Date: Fri, 10 Feb 2006 20:33:48 -0000 Message-ID: hi there, i'm looking for some help with a j pole antenna, it's actually a vhf marine antenna so i hope it will be ok to ask here. my problem is that this antenna used be atop the mast of my yacht untill it blew off breaking the end fitting and pulling free of the coax, because these things are quite expensive and don't seem to last that long, I decided to try repair it as a spare. It fits inside a fibreglass tube, so I carefully cut through the tube and pulled out the antenna parts, which are all intact. my plan was to solder some coax to it and put it back in the tube, then glass the tube back together, but this is where i ran into trouble, i'm unsure where to afix the coax. the antenna i believe is a j antenna, with a 3/4 wave leg and a somewhat less than a 1/4 wave leg returning from the base, however there is no connections on this stub part where the coax has been connected, i had expected there would be. There is, however, 2 pins below the 2 upright legs, these are not electically connected to the upright stub elements, (the 2 upright elements are joined across the bottom). These 2 pins have a length of insulated wire attached to them which stretches over and parallel to the uprights of the stub. The 2 pins are staggered in height which means 1 side of this insulated wire run is approx 75 mm and the other side is approx 70 mm, it runs like an inverted v up the stub from these pins at the base. I'm assuming that the coax should also be soldered to these 2 pins and interacts with the antenna through induction or something. If this is correct does it matter which side of the coax goes to which pin, neither of them are conneced to anything other than each other through the insulated wire, which as i've said, runs above what i beleive to be the antenna stub section. or should the coax be connected at the top of the stub, ( a halfwave from the top), i can't see any sign that the coax was previously fixed there, but then there is no sign that it was previously connected anywhere for that matter hope this makes sense and someone is able advise, thanks for looking and if you can help thanks again. if this all sounds like nonesense, i may be able to put a picture as an attachment but i'm unsure whether it is acceptable in this group. kevin Article: 221570 of rec.radio.amateur.antenna From: Roy Lewallen Subject: Re: folded dipole Date: Fri, 10 Feb 2006 12:59:06 -0800 Message-ID: <11upvks27ah9c2@corp.supernews.com> References: <7289-43ECB6B1-96@storefull-3251.bay.webtv.net> You should realize that this antenna is much narrower banded than a half wave dipole. Using a transmission line matching section with such a high transformation would probably narrow it further. The folded dipole described by Bailey (his data sheet 10-10) can be easily modeled with EZNEC or a similar program. A transmission line matching section can be included in the model if desired. Roy Lewallen, W7EL Richard Harrison wrote: > Cecil, W5DXP wrote: > "Such an antenna could be fed with 1/4 WL of 600 ohm open wire line and > achieve an impedance of 60 ohms looking into the matching section." > > Exactly. > > The actual impedance of the 1/4-wave folded dipole is an inverse > function of the wire diameter. It can be chosen to present 6000 ohms. > Arnold B. Bailey has studied the behavior, developed the formulas, and > published graphs for the user to choose wire sizes for folded dipoles of > either 1/4-wave or 1/2-wave overall length. He does a sample calculation > and showes his work for one particular 1/4-wave folded dipole. > > On page 414 of "TV and Other Receiving Antennas" Bailey writes: > "At first resonance (where the total wire length is 1/2-wave and overall > length is 1/4-wave), the current in the continuous rod (entire wire > length) approaches a constant value, varying from a maximum in the > center (farthest from the drivepoint) to about 0.7 of maximum at the > ends. For this reason the radiation resistance RR approaches the value > for a constant-current rod. The practical value is approximately > RR=570(l squared), where l is the nominal over-all length and equals > 0,25 wavelength, thus resulting in a value of 35.6 ohms." > > The 1/4-wave folded dipole shares some of the characteristics of a > short-circuited stub. It is a resonant circuit element which converts > the low impedance at its short-circuit into a high impedance at its > feedpoint. > > If the 1/4-wave folded dipole is a little short of 1/2-wave around its > perimeter, it presents an inductive reactance. If a little longer > electrically than 1/2-wave around, it presents a capacitive reactance. > > Best regards, Richard Harrison, KB5WZI > Article: 221571 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Coax Connector Question References: Message-ID: Date: Fri, 10 Feb 2006 21:25:42 GMT Robert11 wrote: > But on the other end, for a Female of the same connector type/series, is it > called a: > > PL-258 ? > or just a PL259 Female ? > or... ? > > What's the correct designation for the Female ? Uhhh Robert, a female is a socket, not a plug. :-) If I remember right, the mating socket is an SO-239. -- 73, Cecil http://www.qsl.net/w5dxp Article: 221572 of rec.radio.amateur.antenna From: Owen Duffy Subject: Re: Coax Connector Question Message-ID: References: Date: Fri, 10 Feb 2006 22:29:50 GMT On Fri, 10 Feb 2006 16:09:28 -0500, "Robert11" wrote: >Hello: > >Dumb question, I know, but just can't find a good pix and callout on the >web. Some of the ones I did find don't even agree. > >For a length of coax with a connector on each end: > >The Male UHF is PL-259 let's say. > >But on the other end, for a Female of the same connector type/series, is it >called a: > >PL-258 ? >or just a PL259 Female ? >or... ? > >What's the correct designation for the Female ? > IIRC, PL-259 was a part number specific to a (so called) UHF male connector (plug) for RG8 size coax and with a particular braid anchor scheme. More recently, the term seems to be used to describe any UHF male connector for any sized cable. S0-239 was the part number for a specific panel mounting UHF female connector (socket) with a solder pin for centre conductor connection. Again, the term seems commonly adapted to any female UHF connector. Perhaps the better generic terms are UHF Male and UHF Female, but it seems people like the more technical sounding PL-259 etc. When we talk of BNC series connectors or N type connectors, we don't usually use a specific part number as the designator for the whole series... but that seems the common practice for UHF connectors. Owen -- Article: 221573 of rec.radio.amateur.antenna From: Allodoxaphobia Subject: Re: Coax Connector Question Date: 10 Feb 2006 22:49:03 GMT Message-ID: References: In rec.radio.amateur.antenna, you wrote: > > Dumb question, I know, but just can't find a good pix and callout on > the web. Some of the ones I did find don't even agree. > For a length of coax with a connector on each end: > The Male UHF is PL-259 let's say. > But on the other end, for a Female of the same connector type/series, > is it called a: > > PL-258 ? > or just a PL259 Female ? > or... ? > > What's the correct designation for the Female ? Your gonna love this. It's an SO-239. Of course, there's the chassis mount, the cable attach, the female-to-female feed-through, and more varieties. Standards ARE GREAT! And, there are sooooo many to choose from! Anyway, it's "SO" for SOcket, and "PL" for PLug. The PL-255 is the ol' venerable 1/4", mono audio plug. Jonesy W3DHJ -- Marvin L Jones | jonz | W3DHJ | linux 38.24N 104.55W | @ config.com | Jonesy | OS/2 *** Killfiling google posts: Article: 221574 of rec.radio.amateur.antenna From: Owen Duffy Subject: Re: db Question Message-ID: <2k9qu1pvdacf5houedrb1s6i6e1c5n6p6u@4ax.com> References: Date: Fri, 10 Feb 2006 23:57:21 GMT On Fri, 10 Feb 2006 18:46:13 -0500, "Robert11" wrote: >Hello: > >When a table gives the attenuation (at some freq.) for a length of a >particular coax in db, >are they referring to db in voltage or db in power ? > >Is is correct to ask a question as simply as the following: > >If the attenuation is given as, e.g., 2 db, what Percentage therefore of a >received signal is "lost" >going thru the coax length ? Decibels are a means of expressing a power ratio when used properly. Of course, the power ratio is implied by a voltage or current ratio when the impedance is the same in the two cases being compared. For that reason, you can say that the power ratio in db is 10*log(P1/P2) or 20*log(V1/V2) provided Z remains constant. Nevertheless, voltage or current ratios are often compared using dB where the Z is not the same, and stricly speaking, the power ratio rquires an adjustment for the changed impedance. If the loss is 2dB, the the ratio of power out to power in is 10^(-2/10) or 63%. If the impedance is the same, the ratio of the voltages will be the square root of 63% or 79%. Owen -- Article: 221575 of rec.radio.amateur.antenna From: Roy Lewallen Subject: Re: db Question Date: Fri, 10 Feb 2006 16:23:01 -0800 Message-ID: <11uqbj78re1ad11@corp.supernews.com> References: Robert11 wrote: > Hello: > > When a table gives the attenuation (at some freq.) for a length of a > particular coax in db, > are they referring to db in voltage or db in power ? Both. When voltage and power ratios are measured across the same single impedance, the ratio of voltages in dB is the same as the ratio of power in dB. That is, dB in voltage equals dB in power if only one impedance is involved. That's why there are different formulas for dB voltage and power ratios, to make this happen. And it's the case if a coax cable is terminated in its characteristic impedance so the input and output impedances are the same. It's under this condition that cable loss is specified, so the dB loss represents the loss of both voltage and current. But when you compare the power at the output of a coax cable with the power at the input and the cable isn't terminated in its characteristic impedance, output and input impedances can be very different. The power loss will be somewhat higher than the specification (probably not much, when the matched loss is only 2 dB), but you can have much less or more voltage at the output than the input. So the power and voltage loss in dB can be very different, and you can actually have voltage gain -- although it can be argued that defining dB for a ratio of voltages across two different impedances is a bit shaky and perhaps not too meaningful. > > Is is correct to ask a question as simply as the following: > > If the attenuation is given as, e.g., 2 db, what Percentage therefore of a > received signal is "lost" > going thru the coax length ? 100 * (1 - 10^(-dB/10)) ~ 37% is the fraction of power lost. 100 * (1 - 10^(-dB/20)) ~ 21% is the fraction of voltage lost. These assume that the coax is terminated with its characteristic impedance. And you don't need to put "lost" in quotation marks. It is truly lost as a signal, having been turned into heat. Roy Lewallen, W7EL Article: 221576 of rec.radio.amateur.antenna From: "stargatesg1" References: Subject: Re: db Question Message-ID: <_bbHf.277$CZ4.273@trnddc05> Date: Sat, 11 Feb 2006 01:35:54 GMT Although the other answers given are correct as best as I can remember from school (long time ago), for most practical cb or ham radio purposes just remember that every 3db at a given impedance will 1/2 the power, from radio to antenna, or antenna to radio. RoD "Robert11" wrote in message news:CO2dnTNEFaEiuHDeRVn-oQ@comcast.com... > Hello: > > When a table gives the attenuation (at some freq.) for a length of a > particular coax in db, > are they referring to db in voltage or db in power ? > > Is is correct to ask a question as simply as the following: > > If the attenuation is given as, e.g., 2 db, what Percentage therefore of a > received signal is "lost" > going thru the coax length ? > > Thanks, > Bob > > Article: 221577 of rec.radio.amateur.antenna From: Roy Lewallen Subject: Re: db Question Date: Fri, 10 Feb 2006 17:52:43 -0800 Message-ID: <11uqgrf1qtldd9@corp.supernews.com> References: <11uqbj78re1ad11@corp.supernews.com> dansawyeror wrote: > There are three terms, idb, pdb, and vdb. They are not the same. idb and > pdb have the same value: 10*log10 (i/i0), while vdb is 20*log10(v/v0). > Not quite sure what all these are. But to express a voltage or current ratio in dB, you use: dB = 20 * log(V2/V1) dB = 20 * log(I2/I1) and to express a power ratio in dB, you use: dB = 10 * log(P2/P1) If the voltages or currents are measured at the same impedance as the power, the numerical dB values will be the same. For example, let's suppose we have a 100 ohm resistor with one amp flowing through it. Then there's 100 volts across it, and it's dissipating 100 watts. Double the current to 2 amps. The dB increase in current is 20 * log(2/1) = 6.02 dB The voltage has also doubled to 200 volts, so the dB increase in voltage is 20 * log(200/100) = 6.02 dB The power dissipation is now 400 watts, so the dB increase in power is 10 * log(400/100) = 6.02 dB Cool, huh? Roy Lewallen, W7EL Article: 221578 of rec.radio.amateur.antenna From: dplatt@radagast.org (Dave Platt) Subject: Re: db Question Date: Sat, 11 Feb 2006 02:11:13 -0000 Message-ID: <11uqhu17co8p942@corp.supernews.com> References: <11uqbj78re1ad11@corp.supernews.com> <11uqgrf1qtldd9@corp.supernews.com> In article <11uqgrf1qtldd9@corp.supernews.com>, Roy Lewallen wrote: >The power dissipation is now 400 watts, so the dB increase in power is > > 10 * log(400/100) = 6.02 dB >Cool, huh? Not unless it's a pretty big resistor mounted on a very large heatsink! -- 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: 221579 of rec.radio.amateur.antenna From: "Mr Fed UP" References: <11up7id72jhuv5b@corp.supernews.com> Subject: Re: Anti-oxidant grease question Message-ID: Date: Fri, 10 Feb 2006 21:53:41 -0600 Well that figures.... just like so many on line places to buy things they have everything there but the PRICE!!! They expect me to return or fart around trying to get some one to put a price on everything I want to buy? "John, N9JG" wrote in message news:CF2Hf.548024$084.539297@attbi_s22... > Another product that works very well is Lawson 59933 Copper Anti-Seize > Anti-Corrosion Compound > http://webapp.lawsonproducts.com/website/showItem?itemNum=59933 > This is the same product that comes with a Butternut vertical antenna. It > consists of a synthetic grease base, copper, thickener, and rust > inhibitor. It can withstand temperature ranges from -65°F to 1800°F, which > should be adequate for most ham applications. > > John, N9JG > > "J. Mc Laughlin" wrote in message > news:11up7id72jhuv5b@corp.supernews.com... >>I am a big fan of Penetrox-A. It is sold in a small squeeze-bottle that >>is >> just right for most tasks. It is also a good anti-galling material to >> use >> when screwing SS to anything. > > Article: 221580 of rec.radio.amateur.antenna Date: Sat, 11 Feb 2006 02:14:52 -0700 From: BKR Subject: Re: Some info needed!? References: <1139596215.876386.165400@g44g2000cwa.googlegroups.com> Message-ID: <43edaaf6@nntp.zianet.com> Sounds like the one stolen from my house in a home burglary 2 years ago. Did you get the plastic case with it? KD5RPO ceaser wrote: > I have gotten a GE 40 channel handheld CB is there anything I can do to > this that would go beyoind the normal operating range? thanks > Article: 221581 of rec.radio.amateur.antenna From: Owen Duffy Subject: Re: Coax Connector Question Message-ID: References: Date: Sat, 11 Feb 2006 10:35:16 GMT On Sat, 11 Feb 2006 08:35:59 +0000, Ian White GM3SEK wrote: >Owen Duffy wrote: >> >>Perhaps the better generic terms are UHF Male and UHF Female, but it >>seems people like the more technical sounding PL-259 etc. > >Or is it that they actively DISlike using the name "UHF"? Ian, Possibly. I assume that you are hinting at its performance from an impedance discontinuity point of view... however IMHO the greatest disadvantage of UHF connectors is also apparent at HF. UHF connectors depend on proper alignment of the vee points and notches and the coupling ring being very tight to provide ongoing reliable connection that doesn't degrade with vibration. "UHF" is a bit of a misnomer I agree, but it has market acceptance in one of the largest market places, and that is the generic term for the things. On another note, I was a little surprised to see the mobile phone manufacturers use the mini-UHF connector which inherited all the faults of the UHF connectors earth / coupling ring arrangement. Probably cheaper and a bit smaller than the TNC connector that they appeared to have standardised upon at the time. Then Nokia needed to invent a proprietary connector, all when SMA would have worked fine. Owen -- Article: 221582 of rec.radio.amateur.antenna From: "John, N9JG" References: <11up7id72jhuv5b@corp.supernews.com> Subject: Re: Anti-oxidant grease question Message-ID: Date: Sat, 11 Feb 2006 12:35:03 GMT I did buy a can of the stuff from them, but note that a can will last a lifetime for you and ten of your friends. Just fill out the order on the web page, and one of their sales persons will phone you and give you the price. If you don't like the price, you don't have to complete the order. As I recall, it may have been about $25 for quantity one. The call back and the shipment were both done promptly. "Mr Fed UP" wrote in message news:fadHf.20278$697.1543@bignews3.bellsouth.net... > Well that figures.... just like so many on line places to buy things they > have everything there but the PRICE!!! > They expect me to return or fart around trying to get some one to put a > price on everything I want to buy? > > > "John, N9JG" wrote in message > news:CF2Hf.548024$084.539297@attbi_s22... >> Another product that works very well is Lawson 59933 Copper Anti-Seize >> Anti-Corrosion Compound >> http://webapp.lawsonproducts.com/website/showItem?itemNum=59933 >> This is the same product that comes with a Butternut vertical antenna. It >> consists of a synthetic grease base, copper, thickener, and rust >> inhibitor. It can withstand temperature ranges from -65°F to 1800°F, >> which should be adequate for most ham applications. >> >> John, N9JG >> >> "J. Mc Laughlin" wrote in message >> news:11up7id72jhuv5b@corp.supernews.com... >>>I am a big fan of Penetrox-A. It is sold in a small squeeze-bottle that >>>is >>> just right for most tasks. It is also a good anti-galling material to >>> use >>> when screwing SS to anything. Article: 221583 of rec.radio.amateur.antenna Subject: Re: Coax Losses ? From: "Doc" Date: Sat, 11 Feb 2006 14:38:42 GMT Message-ID: <1139668673_1760@sp6iad.superfeed.net> References: Bob, You're right, for recieving the losses just aren't going to be that much, and not really something to worry a lot about. The average receiver ought to handle and make up for those losses. Losses will only be noticable on frequencies that are not fairly 'close' to one of the harmonics of the design frequency, and then not all that bad. - 'Doc Article: 221584 of rec.radio.amateur.antenna From: Bob Bob Subject: Re: Coax Losses ? References: Message-ID: <4ga1c3-v3e.ln1@p400bob.personal.cox.net> Date: Sat, 11 Feb 2006 08:55:32 -0600 Hi Bob Yes that is correct! You may however get into larger losses from an "unmatched" antenna. This depends on how you feed it. If you (for example) ran a dipole type setup direct connected to the coax end, you will tend to have "notches" as the feedpoint hits a very high impedance value (eg the wire being multiples of a full wavelength but centre fed) Whether this will become an issue or not depends on how much loss occurs. If you (say) cut a dipole for 7MHz there will be this kind of problem at 14 and 28MHz. My gut feel is that both these freqs will be affected adversely. I havent gone to the trouble to guess how wide these "notches" will be but the problem will be worse the higher multiple you go. For transmitting purposes you get around this by using open wire feeder and a tuner. (And for the purists reading I have left out the topic of tuned feeders!) As a general rule the impedance of a dipole dips to a minimum at resonance. A half wave around 75 ohms and 3/2 wavelengths 150 ohms (I think) In between there is a reactive component that adds to the overall figure. Without consulting some books I dont know the average nunbers off hand but impedances higher than a few thousand ohms are not uncommon. Now for some quick maths.. If you try to feed an antenna with an input Z of maybe 2500 ohms with your coax - resulting in a 50:1 VSWR, you will lose about 3dB from the normal line length, plus another 10dB for the mismatch.. I's say that will be upsetting maybe from 21MHz up. This is why its a good reason to use a broadband transformer balun at the antenna feedpoint. Realising that you are probably going to use something like that anyhow.. Apologies for the waffle.. You did ask though! Cheers Bob Robert11 wrote: > Is it correct for me to say that the actual losses really aren't all that > significant or meaningful, > and that a good receiver, which I have, can easily make up for them ? > > That the only thing of real concern would be the S/N ? > > What are the caveats to my statement above ? Article: 221585 of rec.radio.amateur.antenna From: "Mr Fed UP" References: <11up7id72jhuv5b@corp.supernews.com> Subject: Re: Anti-oxidant grease question Message-ID: <5YnHf.1139$S03.729@bignews1.bellsouth.net> Date: Sat, 11 Feb 2006 10:09:26 -0600 Ok thanks. That looks affordable then. With out prices its hard to tell these days. I have an ol AR-10 Ringo that I used back in the 90's for 10 m DXCC and has been in storage for several years. I think putting some compound on the joints may make it work as new again. I been delaying this task so I could get it up and have it work right the first time. Thanks 73 K4TWO Gary "John, N9JG" wrote in message news:XRkHf.760597$x96.380669@attbi_s72... >I did buy a can of the stuff from them, but note that a can will last a >lifetime for you and ten of your friends. Just fill out the order on the >web page, and one of their sales persons will phone you and give you the >price. If you don't like the price, you don't have to complete the order. >As I recall, it may have been about $25 for quantity one. The call back and >the shipment were both done promptly. > > "Mr Fed UP" wrote in message > news:fadHf.20278$697.1543@bignews3.bellsouth.net... >> Well that figures.... just like so many on line places to buy things they >> have everything there but the PRICE!!! >> They expect me to return or fart around trying to get some one to put a >> price on everything I want to buy? >> >> >> "John, N9JG" wrote in message >> news:CF2Hf.548024$084.539297@attbi_s22... >>> Another product that works very well is Lawson 59933 Copper Anti-Seize >>> Anti-Corrosion Compound >>> http://webapp.lawsonproducts.com/website/showItem?itemNum=59933 >>> This is the same product that comes with a Butternut vertical antenna. >>> It consists of a synthetic grease base, copper, thickener, and rust >>> inhibitor. It can withstand temperature ranges from -65°F to 1800°F, >>> which should be adequate for most ham applications. >>> >>> John, N9JG >>> >>> "J. Mc Laughlin" wrote in message >>> news:11up7id72jhuv5b@corp.supernews.com... >>>>I am a big fan of Penetrox-A. It is sold in a small squeeze-bottle that >>>>is >>>> just right for most tasks. It is also a good anti-galling material to >>>> use >>>> when screwing SS to anything. > > Article: 221586 of rec.radio.amateur.antenna From: "John, N9JG" References: <11up7id72jhuv5b@corp.supernews.com> <5YnHf.1139$S03.729@bignews1.bellsouth.net> Subject: Re: Anti-oxidant grease question Message-ID: Date: Sat, 11 Feb 2006 16:26:11 GMT Be careful about trusting my memory. I bought the can several months ago, and I didn't save the invoice because I knew I had more than a lifetime's supply. When you do find the price, go ahead and post it here. "Mr Fed UP" wrote in message news:5YnHf.1139$S03.729@bignews1.bellsouth.net... > Ok thanks. That looks affordable then. With out prices its hard to tell > these days. > I have an ol AR-10 Ringo that I used back in the 90's for 10 m DXCC and > has > been in storage for several years. I think putting some compound on the > joints > may make it work as new again. I been delaying this task so I could get > it > up and have it work right the first time. > > Thanks 73 K4TWO Gary > > > > > "John, N9JG" wrote in message > news:XRkHf.760597$x96.380669@attbi_s72... >>I did buy a can of the stuff from them, but note that a can will last a >>lifetime for you and ten of your friends. Just fill out the order on the >>web page, and one of their sales persons will phone you and give you the >>price. If you don't like the price, you don't have to complete the order. >>As I recall, it may have been about $25 for quantity one. The call back >>and the shipment were both done promptly. >> > Article: 221587 of rec.radio.amateur.antenna From: "David G. Nagel" Subject: Re: db Question Date: Sat, 11 Feb 2006 10:30:24 -0600 Message-ID: <11us495apthgse0@corp.supernews.com> References: <11uqbj78re1ad11@corp.supernews.com> Ian White GM3SEK wrote: > dansawyeror wrote: > >> There are three terms, idb, pdb, and vdb. They are not the same. idb >> and pdb have the same value: 10*log10 (i/i0), while vdb is >> 20*log10(v/v0). >> > > "A decibel is a decibel is a decibel". There is only one kind of > decibel, and by definition it is based on a power ratio. > > Decibels are always used for comparing power levels. If you're comparing > current or voltage levels, you first have to convert them into a power > ratio, and that is the reason why you have to use a different formula. > Your starting-point was different, but the definition of the decibel > remains the same. > > > There is a similar-looking term, sometimes written as either "dBV", > "dBmV" or "dBuV", but that has a different meaning. Anything tagged on > after the "dB" indicates a standard reference level. For example, "dBV" > means "a power ratio in decibels, relative to the power level of a 1V > rms signal measured at the same point in the circuit." > > Actually what I was taught was the standard unit is the BEL, named in honor of Alexander Graham Bell. This is a large value hence the DECIBEL or 1/10 of a BEL is generally used. Dave WD9BDZ Article: 221588 of rec.radio.amateur.antenna From: John Ferrell Subject: Re: Anti-oxidant grease question Message-ID: References: <11up7id72jhuv5b@corp.supernews.com> Date: Sat, 11 Feb 2006 16:36:28 GMT Here is a penetrox link from a ham supplier. http://www.dxengineering.com/Parts.asp?ID=17&PLID=119&SecID=90&DeptID=21&PartNo=DXE%2DP8A On Fri, 10 Feb 2006 21:53:41 -0600, "Mr Fed UP" wrote: >Well that figures.... just like so many on line places to buy things they >have everything there but the PRICE!!! >They expect me to return or fart around trying to get some one to put a >price on everything I want to buy? > > >"John, N9JG" wrote in message >news:CF2Hf.548024$084.539297@attbi_s22... >> Another product that works very well is Lawson 59933 Copper Anti-Seize >> Anti-Corrosion Compound >> http://webapp.lawsonproducts.com/website/showItem?itemNum=59933 >> This is the same product that comes with a Butternut vertical antenna. It >> consists of a synthetic grease base, copper, thickener, and rust >> inhibitor. It can withstand temperature ranges from -65°F to 1800°F, which >> should be adequate for most ham applications. >> >> John, N9JG >> >> "J. Mc Laughlin" wrote in message >> news:11up7id72jhuv5b@corp.supernews.com... >>>I am a big fan of Penetrox-A. It is sold in a small squeeze-bottle that >>>is >>> just right for most tasks. It is also a good anti-galling material to >>> use >>> when screwing SS to anything. >> >> > John Ferrell W8CCW Article: 221589 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: how to build a high Q low loss counterpoise coil References: Message-ID: Date: Sat, 11 Feb 2006 17:14:02 GMT dansawyeror wrote: > Reg's counterpoise program predicts the effective ground of a > centerloaded vertical on 75 meters can be improved by a tuned relatively > short counterpoise system. This is dependent on a large, high Q, low > loss tuning coil. Are these elevated radials? How elevated? High-Q coils in ground-level radials would probably be a waste of time and effort. -- 73, Cecil http://www.qsl.net/w5dxp Article: 221590 of rec.radio.amateur.antenna From: richardharrison@webtv.net (Richard Harrison) Subject: Re: db Question Date: Sat, 11 Feb 2006 11:03:51 -0600 Message-ID: <22778-43EE18F7-598@storefull-3258.bay.webtv.net> References: Ian, GM3SEK wrote: "Decibels are always used for comparing power levels." True. The decibel or dB is a power ratio. The dB alone says nothing about the quantity of power, only the ratio between powers. Thus, the dB is useful to express the gain of a linear amplifier or the loss of a resistance pad. The dB can be used to express a power level by reference to some known quantity of power. In this case, the ratio is said to be so many dB above or below the reference level. In the telephone industry, the most common reference level is one milliwatt. Signal loss is common. Cables fave loss per foot or mile. Attenuation is a division process. Amplification is a multiplication process. It is convenient to express the amount of power at a particular point in a system as being so many dB above or below a reference power of one milliwatt because adding and subtracting decibels gives the same answers as multiplying and dividing powers. Decibels above or below one milliwatt is usually abbreviated as + or - dBm. DBa and dBrn indicate the interfering effect of noise in a communications channel. DBx is used to indicate crosstalk coupling into telephone circuits. VU is a volume unit. Reference is to one milliwatt, same as the dBm, but the ballistics of the meter are specified so that a standard response is made to varying signal level. Other dB units are easily contrived. There are dBw (dB referenced to one watt), dBk (dB referenced to one kilowatt), dBRAP (dB above reference acoustical power which is defined at 10 ro the minus 16 watts), etc, etc, etc. Best regards, Richard Harrison, KB5WZI Article: 221591 of rec.radio.amateur.antenna From: richardharrison@webtv.net (Richard Harrison) Subject: Re: Why is my car radio acting strangly? Date: Sat, 11 Feb 2006 11:23:37 -0600 Message-ID: <22778-43EE1D99-599@storefull-3258.bay.webtv.net> References: <1139313678.316393.97290@z14g2000cwz.googlegroups.com> J. Wetstein wrote: "Could it have to do with static control (somehow) because of the winter weather?" Cold brought the FM and AM antennas together. They liked it and wanted to marry.The wedding wasn`t much, but the reception was great! Best regards, Richard Harrison, KB5WZI Article: 221592 of rec.radio.amateur.antenna From: "RST Engineering" References: <11uqbj78re1ad11@corp.supernews.com> <11us495apthgse0@corp.supernews.com> Subject: Re: db Question Date: Sat, 11 Feb 2006 09:42:11 -0800 Message-ID: <6c371$43ee21ee$42512a4c$17466@DIALUPUSA.NET> Hm. I was taught that the egotistical SOB named it after himself, no honor involved. Jim > Actually what I was taught was the standard unit is the BEL, named in > honor of Alexander Graham Bell. This is a large value hence the DECIBEL or > 1/10 of a BEL is generally used. > > Dave WD9BDZ Article: 221593 of rec.radio.amateur.antenna From: "Mr Fed UP" References: <11up7id72jhuv5b@corp.supernews.com> <5YnHf.1139$S03.729@bignews1.bellsouth.net> Subject: Re: Anti-oxidant grease question Message-ID: Date: Sat, 11 Feb 2006 12:06:25 -0600 Sorry ... whine wasn't about the price... it was about advert's with out any prices. They want our business but too lazy or dumb to post prices with the ad's Big radio stores included check most of the ad's in your handy QST and you can see that they make YOU work to find prices. Maybe Wal-Mart will get into radios , then the price competition can start LOL My apologies to those who know all and have deep pockets. If you don't like the postings.... well if your that smart I don't need to finish. Thanks 73 K4TWO Gary "Larry Benko" wrote in message news:PdGdnUBVs_mkgHPeRVn-vw@comcast.com... > Come on folks. This stuff is cheap compared to maintenance. A 1 minute > web search finds Noalox at Home Depot stores for $8.95 for an 8oz. bottle. > Penetrox is about the same price but not sold by Home Depot. > > Larry, W0QE Article: 221594 of rec.radio.amateur.antenna From: Butch Magee Subject: Re: SteppIR antennas Date: Sat, 11 Feb 2006 12:58:27 -0600 Message-ID: <11usculi4pp2qce@corp.supernews.com> References: <3F791831.3090306@optonline.net> <3F799AE4.FA8E0945@cwis.net> <3f7a5748$1_5@corp.newsgroups.com> Kenneth Grimm wrote: > On Tue, 30 Sep 2003 23:17:30 -0500, Cecil Moore > wrote: > > >> Uncle Peter wrote: >> >>>Nothing is forever. >> >>Not even time. :-) > > > This has yet to be conclusively demonstrated.... > > Ken K4XL > k4xl@arrl.net > >Time is also warped, not just us Article: 221595 of rec.radio.amateur.antenna From: Butch Magee Subject: Re: Some info needed!? Date: Sat, 11 Feb 2006 13:01:55 -0600 Message-ID: <11usd55v98upc0@corp.supernews.com> References: <1139596215.876386.165400@g44g2000cwa.googlegroups.com> ceaser wrote: > I have gotten a GE 40 channel handheld CB is there anything I can do to > this that would go beyoind the normal operating range? thanks > I think it's 5 watts AM. FIVE WATTS ONLY, AM ONLY. KF5DE Article: 221596 of rec.radio.amateur.antenna From: "David G. Nagel" Subject: Re: db Question Date: Sat, 11 Feb 2006 13:37:16 -0600 Message-ID: <11usf7kab6etd7b@corp.supernews.com> References: <11uqbj78re1ad11@corp.supernews.com> <11us495apthgse0@corp.supernews.com> <6c371$43ee21ee$42512a4c$17466@DIALUPUSA.NET> RST Engineering wrote: > Hm. I was taught that the egotistical SOB named it after himself, no honor > involved. > > Jim > > > > >>Actually what I was taught was the standard unit is the BEL, named in >>honor of Alexander Graham Bell. This is a large value hence the DECIBEL or >>1/10 of a BEL is generally used. >> >>Dave WD9BDZ > > > For a (fairly) comprehensive write up on the "decibel" go to https://ewhdbks.mugu.navy.mil/decibel.htm . Also: Alexander Graham Bell From Wikipedia, the free encyclopedia Bell and decibel The bell is a unit of measurement invented by Bell Labs and named after Bell. The bell was too large for everyday use, so the decibel (dB), equal to 0.1 B, became more commonly used. The dB is commonly used as a unit for measuring sound intensity. Dave WD9BDZ Article: 221597 of rec.radio.amateur.antenna From: dplatt@radagast.org (Dave Platt) Subject: Re: Coax Connector Question Date: Sat, 11 Feb 2006 19:46:20 -0000 Message-ID: <11usfocfb860ff8@corp.supernews.com> References: In article , Owen Duffy wrote: >"UHF" is a bit of a misnomer I agree, but it has market acceptance in >one of the largest market places, and that is the generic term for the >things. As I have heard it, this is a case of TLA (three-letter acronym) collision. The full term for these connectors started out "Universal High Frequency" (UHF) and did not imply that they were used, or good for, "Ultra-High Frequency" operation. -- 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: 221598 of rec.radio.amateur.antenna From: Roy Lewallen Subject: Re: Coax Losses ? Date: Sat, 11 Feb 2006 12:35:52 -0800 Message-ID: <11usilchl6j771e@corp.supernews.com> References: You have the right idea. Signal/noise ratio is all that counts. When receiving HF, feedline loss almost never matters. The reason is that atmospheric noise is strong, and unless a receiver is exceptionally noisy and/or an antenna is exceptionally lossy, the atmospheric noise will be much greater than the receiver noise. The input to the receiver consists of the signal and atmospheric noise, to which the receiver adds its own noise. As long as the atmospheric noise is much greater than the receiver noise, you won't hear the receiver noise. Any attenuation in the antenna system will attenuate both the signal and the atmospheric noise equally, so the signal/noise ratio, which determines what you can hear, doesn't change. Any gain ahead of or within the receiver has the same effect. Atmospheric noise declines as the frequency increases, so it might be possible to start hearing some receiver noise over it as you approach 30 MHz, particularly if your receiver is unusually noisy and/or the antenna system unusually lossy. As soon as receiver noise becomes audible over the atmospheric noise, the rules change. Then, attenuation ahead of the receiver will reduce the signal but not the receiver noise -- which is now the "noise" part of the signal/noise ratio --, so it *will* decrease the signal/noise ratio. There's a very simple test to determine whether reducing the loss will improve your ability to hear signals. Tune your receiver to a spot with no signals in the frequency band of interest. Turn up the volume so you can clearly hear the background noise. Then disconnect your antenna(*). If the noise decreases, it means that atmospheric noise is dominating, so reducing loss won't help the signal/noise ratio. If the noise doesn't decrease, you're hearing receiver noise with the antenna connected and you'd benefit by reducing losses ahead of the receiver. You'll probably find that the noise will decrease by quite a few dB when you disconnect the antenna, and this represents the amount of loss you can add before your ability to hear signals suffers. When receiving HF, about the only way you can improve your signal/noise ratio is by using a directional antenna. This will reduce the atmospheric noise coming from unneeded directions. Particular kinds of antennas can also improve the signal/noise ratio if the dominant noise is man made and coming from a nearby source. (*) In a really marginal case, you might need to replace the antenna with a dummy load for this test -- an ordinary small 47 or 51 ohm resistor will suffice -- but it usually isn't necessary. Roy Lewallen, W7EL Robert11 wrote: > Hi, > > Just getting started with all of this, and want to say a quick thanks to > everyone for all the help. > > Another question: > > Am I interpreting this more or less correctly: > > Looking at all the different types of coax available. > Will be for a receive-only HF antenna. > Antenna will have to be in the backyard about 150 feet or so from house. > > The db losses are beginning to add up; at the upper limit of my interest of > 30 MHz > we are getting close to around 3.5 db or so. > > Is it correct for me to say that the actual losses really aren't all that > significant or meaningful, > and that a good receiver, which I have, can easily make up for them ? > > That the only thing of real concern would be the S/N ? > > What are the caveats to my statement above ? > > Thanks, > Bob > > > Article: 221599 of rec.radio.amateur.antenna From: "J. Mc Laughlin" Subject: Re: New 4nec2 version Date: Sat, 11 Feb 2006 15:42:55 -0500 Message-ID: <11usiuk6fbnjr3b@corp.supernews.com> References: <1138119779.443881.171030@g49g2000cwa.googlegroups.com> <43D82AEB.1020009@comcast.net> <1138275019.217196.21700@g14g2000cwa.googlegroups.com> <277Cf.110589$AP5.60182@edtnps84> Dear Frank: I run licensed NEC4 with an appropriate version of EZNEC on a PC. The OS is W2000. 73 Mac N8TT -- J. Mc Laughlin; Michigan U.S.A. Home: JCM@Power-Net.Net "Frank" wrote in message news:277Cf.110589$AP5.60182@edtnps84... > > You mention "Nec 4 cards". Do you actually support NEC 4? I plan to obtain > a license for NEC 4 in the near future, and your interface looks > interesting; The cost of GNEC from Nittany Scientific is a bit high, but > thought it is probably the only way to run NEC 4 on a PC. > > Frank > > Article: 221600 of rec.radio.amateur.antenna From: Russ Subject: Re: SteppIR antennas Message-ID: References: <3F791831.3090306@optonline.net> <3F799AE4.FA8E0945@cwis.net> <3f7a5748$1_5@corp.newsgroups.com> <11usculi4pp2qce@corp.supernews.com> Date: Sat, 11 Feb 2006 22:24:20 GMT On Sat, 11 Feb 2006 12:58:27 -0600, Butch Magee wrote: >Kenneth Grimm wrote: >> On Tue, 30 Sep 2003 23:17:30 -0500, Cecil Moore >> wrote: >> >> >>> Uncle Peter wrote: >>> >>>>Nothing is forever. >>> >>>Not even time. :-) >> >> >> This has yet to be conclusively demonstrated.... >> >> Ken K4XL >> k4xl@arrl.net >> >>Time is also warped, not just us Time, as we humans know it does not exist. It is an artificial contraint we place on the universe so we can better understand it. R Article: 221601 of rec.radio.amateur.antenna From: "Frank" References: <1138119779.443881.171030@g49g2000cwa.googlegroups.com> <43D82AEB.1020009@comcast.net> <1138275019.217196.21700@g14g2000cwa.googlegroups.com> <277Cf.110589$AP5.60182@edtnps84> <11usiuk6fbnjr3b@corp.supernews.com> Subject: Re: New 4nec2 version Message-ID: Date: Sat, 11 Feb 2006 22:39:21 GMT Thanks for the info Mac. I see EZNEC/4 is $600.00, compared to $795.00 for GNEC. I have no trouble with the FORTRAN compiled program on my PC, although the graphics leave a little to be desired. Not sure what I will do to improve it yet. Not that interested in GUI inputs, as I find it far easier to edit NEC code directly. 73, Frank VE6CB "J. Mc Laughlin" wrote in message news:11usiuk6fbnjr3b@corp.supernews.com... > Dear Frank: > I run licensed NEC4 with an appropriate version of EZNEC on a PC. The > OS is W2000. > 73 Mac N8TT > > -- > J. Mc Laughlin; Michigan U.S.A. > Home: JCM@Power-Net.Net > "Frank" wrote in message > news:277Cf.110589$AP5.60182@edtnps84... > >> >> You mention "Nec 4 cards". Do you actually support NEC 4? I plan to > obtain >> a license for NEC 4 in the near future, and your interface looks >> interesting; The cost of GNEC from Nittany Scientific is a bit high, but >> thought it is probably the only way to run NEC 4 on a PC. >> >> Frank >> >> > > Article: 221602 of rec.radio.amateur.antenna From: "Hal Rosser" References: <1139313678.316393.97290@z14g2000cwz.googlegroups.com> <_aVGf.2059$UD1.320@bignews2.bellsouth.net> <91015$43ec991b$d8602e79$2545@ALLTEL.NET> Subject: Re: Why is my car radio acting strangly? Message-ID: Date: Sat, 11 Feb 2006 18:46:15 -0500 "Christopher Thompson" wrote in message news:91015$43ec991b$d8602e79$2545@ALLTEL.NET... > that raises a good question. had there been any engine work where they may > have inadvertantly left the ground strap from the body to the engine off or > loose? keep in mind as posted below the body is grounded to the engine > block, and the battery neg goes to the engine block. It was an old Buick - no telling how much work had been done. The ground strap was still there. The 12½ in of #12 from the negative terminal to a screw on the body fixed it, and only cost 60¢ or so. I had started tracing circuits from the + side, so it took longer to figure it out than it took to find the ¢ key and the ½ key on my keyboard. Article: 221603 of rec.radio.amateur.antenna From: "Charlie" Subject: Re: Coax Sources ? Date: Sat, 11 Feb 2006 17:49:13 -0600 Message-ID: <11usu07a90vj3a3@news.supernews.com> References: <4kpsu1t1afnu6vq2jcr1b0c9iufv7g9tjd@4ax.com> Radio Ware makes excellent cable assemblies. I have nearly 500ft of their ready made Davis Bury Flex 9914. 1. http://radiobooks.com/products/ca9914f.htm -- Charlie-AD5TH www.deepsouthnet.net "Dan Richardson" wrote in message news:4kpsu1t1afnu6vq2jcr1b0c9iufv7g9tjd@4ax.com... > On Sat, 11 Feb 2006 14:59:25 -0500, "Robert11" > wrote: > >>Hello: >> >>Other than the Wireman and Davis, anyone have any sources for bulk coax, >>and >>made up coax lengths with fittings >>they would care to recommend ? >> >>Thanks. >> > > http://www.cablexperts.com/ > > > > email: k6mhearrlnet > http://www.k6mhe.com/ Article: 221604 of rec.radio.amateur.antenna From: "kevin" Subject: Re: help appreciated with unusual j pole feed Date: Sun, 12 Feb 2006 17:08:22 -0000 Message-ID: References: <1139695852.501908.208960@g47g2000cwa.googlegroups.com> thanks for that tom, i have tried it experimentally coupled to the pins but it was dissapointing, infact i needed to disconnect the outer coax to get any signal at all. think i'll try build something, perhaps j pole or maybe skirted dipole type. thanks for your answers tom. cheers kevin "K7ITM" wrote in message news:1139695852.501908.208960@g47g2000cwa.googlegroups.com... > No, posting a picture here wouln't be acceptable. You could send it to > those who ask, though. From your description, it sounds like the loop > of insulated wire between the two pins couples to the stub--the > 1/4-wave bottom of the antenna. I guess that stub is over 400mm long, > so your wire only goes up a fraction of that distance. Someone may > have engineered it, or they may have determined it empiracally, but it > sounds to me like quite an acceptable way to couple to the antenna. > And that seems like the most likely reason it's there, so that's where > I'd connect the coax. I'd guess that there isn't much difference > between the two possible polarities of connecting the coax to those > pins. > > Cheers, > Tom >