Article: 217947 of rec.radio.amateur.antenna From: "Reg Edwards" Subject: Re: Magnetic Loop !!! Date: Sat, 1 Oct 2005 17:36:49 +0000 (UTC) Message-ID: References: <433D46F0.D0533E2B@shaw.ca> <433D7754.F019C9B2@shaw.ca> <11jrte940qbbf67@corp.supernews.com> <11jsujdpigc5dff@corp.supernews.com> Hello Lee, Thanks for letting me know that by giving your magloop half-a-chance it performs according to expectations. You have also demonstrated that the G5RV is not so hot as it is made out to be by salesmen and they who have never tried anything else. No disrespect intended to G5RV himself, now deceased, who claimed only that it had a nice radiation pattern on 14.15 MHz which enabled him to work both Europe and North America from South America without having to climb ladders and change anything. The magloop is by far the most efficient of all the antennas of roughly the same physical size. Both theoretically and in practice. It will do even better if you can get it well above ground in the vertical plane. In the horizontal plane it works best at the higher heights, above surrounding obstructions like buildings. But in such surroundings there is room to erect full-size dipoles anyway, which will obviously do better still. The main disadvantage on the 160 and 80 meter bands is the size, physical and capacitance-wise, of the variable tuning capacitor. You need a vaccuum capacitor of about 1000 pF max. By correct choice of loop dimensions and minimum capacitor setting the 40 meter band can also be covered. On 40 meters a small magloop can be highly efficient. Investigate using program MAGLOOP4. Are you using the small internal coupling loop, about 1/5 diameter of main loop, to match to a 50-ohm feedline? This is the best and most simple way to go, A different ratio small loop diameter is needed for other feedline impedances. The circuit behaves as if the turns ratio on a transformer is being changed. Let us know how your experiments proceed. ---- Reg, G4FGQ. Article: 217948 of rec.radio.amateur.antenna From: "Reg Edwards" Subject: Re: Small, non-resonant, horiz. loop. was Re: Magnetic Loop !!! Date: Sat, 1 Oct 2005 19:33:49 +0000 (UTC) Message-ID: References: <433D46F0.D0533E2B@shaw.ca> <433D7754.F019C9B2@shaw.ca> <11jrte940qbbf67@corp.supernews.com> <11jsujdpigc5dff@corp.supernews.com> <11jtdf05htl4j4a@corp.supernews.com> "J. Mc Laughlin" wrote > Dear Reg (G4FGQ): > > I note with interest that your note was written in the early afternoon. ========================================== My Dear J. Mc Laughlin, Thank you for your interest in my early afternoon state of health. It is now 19.15 hours and I have just started on a bottle of Sierra Valley, Californian, Ruby Cabernet. > > The subject of my communication is: small (much smaller than a > wavelength) - non-resonant (input impedance almost entirely inductive if one > looks into a single opening in the loop) - horizontal - loop antenna (no > substances with significant magnetic properties are in the vicinity of the > loop antenna) - used to receive incident EM waves (which have both E and H > components). SNRHL receiving antennas > > I do not know the definition of a "magloop." Apparently, such a beastie > comprises a resonant loop antenna. ======================================= "Magloop" describes a small, single-turn, thick conductor, usually made from copper water pipe, circular, hexagonal or square in shape, loop. The two ends of the loop are connected together via a variable capacitor. The capacitor tunes the inductance of the loop to a resonant frequency at which everything happens. The term "magnetic" arises because the near-field of a transmitting loop is mainly magnetic as distinct from the electric field. On receive it is more sensitive the magnetic field than the electric field. ======================================= > No knowledgeable person would disagree that a single tuned network with > a Q of 1000 is "narrow." > > My interest in SNRHL receiving antennas comes from an interest in > practical HF receiving antennas that are resistive to types of noise that > appear only to be present at isolated, open, rural, otherwise-low-noise > sites. The noise involved does not occur in urban areas or even rural sites > with many trees. ===================================== The noise in rural, open, oceanic areas is just the same sort as in built-up, residential, city and industrial areas. It is all random but there is just a lot less of it. An antenna of any sort is just as sensitive to noise as it is to signals provided both noise and signals are coming from the same direction and elevation. ====================================== > > Consider some of the excellent wine from Michigan this evening. This > state, with a coastline almost the same length as that of the island of > Great Britain, produces some excellent products for your enjoyment. > ======================================= Everybody has heard of the State of Michigan with its capital city of Detroit. I have always thought of it as an industrial state similar to my own area of the city of Birmingham and the surrounding Black Country of England. It is the manufacuring areas which produce the REAL wealth of this World of ours. Not forgetting the farmers. Never having had the opportunity to visit Michigan it has not occurred to me that the land could also grow grapes and produce wine. (Actually, we do produce respectable wine here in cool-climate industrial England. But not much of it.) It is now 20.00 hrs and too late to go shopping at my local super-market. Nevertherless, at my next visit I shall keep my eyes open for "Michigan" on the wine bottle labels. ---- Reg, G4FGQ. From Fri Oct 7 11:45:29 EDT 2005 Article: 217949 of rec.radio.amateur.antenna From: Matt Osborn <> Newsgroups: alt.ham-radio.vhf-uhf,rec.radio.amateur.antenna,rec.radio.amateur.dx,rec.radio.amateur.equipment,rec.radio.amateur.policy Subject: Re: "Hams to the Rescue After Katrina" MSNBC News Article Date: Sat, 01 Oct 2005 14:41:19 -0500 Organization: Posted via Supernews, http://www.supernews.com Message-ID: <3iptj1d8gviv3i1agb619ec1pshgovrmav@4ax.com> References: <0h0rj1ho78qtofjckgk0nrrqu4mgn8di5k@4ax.com> <0lqrj159qhmnctjgq3srd8br32uftls2u1@4ax.com> <433dedcd$0$32199$39cecf19@news.twtelecom.net> <7d1sj1ljfil7mk2a45g84havhdhtn0t32b@4ax.com> X-Newsreader: Forte Agent 2.0/32.652 X-No-Archive: yes MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-Complaints-To: abuse@supernews.com Lines: 15 Path: news1.isis.unc.edu!arclight.uoregon.edu!canoe.uoregon.edu!newsfeed.news.ucla.edu!newsfeed.berkeley.edu!ucberkeley!sn-xit-03!sn-xit-11!sn-xit-08!sn-post-01!supernews.com!corp.supernews.com!not-for-mail Xref: news1.isis.unc.edu alt.ham-radio.vhf-uhf:22947 rec.radio.amateur.antenna:217949 rec.radio.amateur.dx:29648 rec.radio.amateur.equipment:208836 rec.radio.amateur.policy:251318 On Sat, 01 Oct 2005 08:21:47 -0700, Richard Clark wrote: >On Sat, 01 Oct 2005 09:21:31 -0500, Matt Osborn <> wrote: > >>The tale is of two sheep > >Hi Matt, > >Such problems. It's good to see we can agree on at least that much. -- msosborn at msosborn dot com Article: 217950 of rec.radio.amateur.antenna From: LT Subject: Re: Magnetic Loop !!! Date: Sat, 01 Oct 2005 20:57:15 -0000 Message-ID: References: <433D46F0.D0533E2B@shaw.ca> <433D7754.F019C9B2@shaw.ca> <11jrte940qbbf67@corp.supernews.com> <11jsujdpigc5dff@corp.supernews.com> Hi Lee, I'm a little confused about the bandwidth that you're getting. Maybe it can be attributed to losses which widen the SWR bandwidth. That's not necessarily a bad thing. I have used an AEA IsoLoop antenna that is about the same size as your loop antenna but has a low loss butterfly capacitor for tuning 10-30 MHz. On 20 meters the bandwidth is only about 20 or 30KHz(can't remember exactly since I haven't used it for a couple of years). It works great if you park yourself on a frequency but it is a pain to use for hunt and pounce. Besides the null using vertical polarization, is it possible that for your local friend you may have been cross-polarized. Usually direct wave cross-polarization is on the order 20db which accounts for the 2 to 3 S units of change from vertical to horizontal. Have fun with your new toy! 73 LT > Hi Reg.... > > I took my little 1 meter dia ( 10 ft circ ) loop outside lunchtime and > mounted it verticaly 2ft off the lawn and tested it, not expecting > anything special and found that comparing it to the G5RV that there > was no noticable difference between the two!!...my friend and i > switched out our preamps and attenuator in. > > I even turned the loop face on and edge on with a change of 2-3 S > points.. So, needless to say, i am rather impressed with the > performance and bandwidth of 2:1 SWR about 180k.....so much so that i > am thinking seriously of going for a 20 ft circumference or larger for > 80 and 40 metres.... > > Regards. > > Lee....G6ZSG.....Well impressed!!! :-) > > > Article: 217951 of rec.radio.amateur.antenna From: Owen Duffy Subject: Re: Magnetic Loop !!! Message-ID: References: <433D46F0.D0533E2B@shaw.ca> <433D7754.F019C9B2@shaw.ca> <11jrte940qbbf67@corp.supernews.com> <11jsujdpigc5dff@corp.supernews.com> Date: Sat, 01 Oct 2005 21:01:01 GMT On Sat, 01 Oct 2005 13:42:40 GMT, "Lee" wrote: >I took my little 1 meter dia ( 10 ft circ ) loop outside lunchtime and >mounted it verticaly 2ft off the lawn and tested it, not expecting anything Did your "little loop" grow since your first post... it was 1m in circumfrence in the beginning? Owen -- Article: 217952 of rec.radio.amateur.antenna From: "Fred W4JLE" References: <1jepj1p4qngh1ivp6bo4c1rc3vulugi6d5@4ax.com> <8bgpj11ofckhvd5dcg0umujbqav3508g9m@4ax.com> <0h0rj1ho78qtofjckgk0nrrqu4mgn8di5k@4ax.com> <2ym%e.16419$Xl2.3609@twister.nyroc.rr.com> <021sj1hb84shphia0dq78pl55r0q65sntl@4ax.com> <7d3a5$433e926c$97d558d8$32550@ALLTEL.NET> Subject: Re: "Hams to the Rescue After Katrina" MSNBC News Article Date: Sat, 1 Oct 2005 18:53:26 -0400 Message-ID: <8b50$433f1398$97d558d8$27686@ALLTEL.NET> Nah, I used to beat the crap out of wooses like you and take their lunch money. Enjoyed watching them cry. If I were standing in front of you, you would be peeing your pants and hollering "Mommy". Your type is only brave when behind a teacher or a keyboard. Get a life or get educated enough to use your newsreader correctly so you may avoid apoplexy... "Pat Stevens" wrote in message news:Qby%e.16485$Xl2.3691@twister.nyroc.rr.com... > You probably call the police a nazi, too, when they pull you over for > speeding. How come everyone believes that they don't need to follow the > rules and that when they have it pointed out to them that they are outside > the rules, they are being "picked on." Is that what you were in school? > > "Fred W4JLE" wrote in message > news:7d3a5$433e926c$97d558d8$32550@ALLTEL.NET... > >I bet you were a hall monitor in school... > > > > It must be really boring to have a life that is only enriched by being a > > net > > Nazi. > > Article: 217953 of rec.radio.amateur.antenna From: "Fred W4JLE" References: <1jepj1p4qngh1ivp6bo4c1rc3vulugi6d5@4ax.com> <8bgpj11ofckhvd5dcg0umujbqav3508g9m@4ax.com> <0h0rj1ho78qtofjckgk0nrrqu4mgn8di5k@4ax.com> <433de88a$0$32196$39cecf19@news.twtelecom.net> Subject: Re: "Hams to the Rescue After Katrina" MSNBC News Article Date: Sat, 1 Oct 2005 19:00:01 -0400 Message-ID: Richard, if the same 3 were used to design the wheels as the tires, you would never know the difference. PI is really smart in that it knows about both Metric and Inches :>) "Richard Clark" wrote in message news:dhttj1d92o8qhv2m93njjuhvefdbg52tr1@4ax.com... > On Sat, 01 Oct 2005 16:06:08 -0400, Mike Coslo > wrote: > > But pi is exactly 3 in some circles....... > > > > While we are busy putting "intelligent design" into schools, I suggest > >we start putting "faith based mathematics" in next. > > Hi Mike, > > If I recall correctly, the forebears of the untelligent design crowd, > during the scopes monkey trial, attempted to mandate that pi was equal > to 22/7ths. However, I don't see where faith attaches to 22 and 7 was > always a cabalistic device of the middle ages. > > Close enough for as many as 3 would be. > > I would hate to drive on their 13/14/15 inch tires tho'. ;-) > > 73's > Richard Clark, KB7QHC Article: 217954 of rec.radio.amateur.antenna From: "Fred W4JLE" References: <433D46F0.D0533E2B@shaw.ca> <433D7754.F019C9B2@shaw.ca> <11jrte940qbbf67@corp.supernews.com> <11jsujdpigc5dff@corp.supernews.com> Subject: Re: Magnetic Loop !!! Date: Sat, 1 Oct 2005 19:04:39 -0400 Message-ID: What about a fractal magloop Reg? Should be even smaller. :>) "Reg Edwards" wrote in message news:dhmhfg$chb$1@nwrdmz01.dmz.ncs.ea.ibs-infra.bt.com... > The magloop is by far the most efficient of all the antennas of > roughly the same physical size. Both theoretically and in practice. It > will do even better if you can get it well above ground in the > vertical plane. > Article: 217955 of rec.radio.amateur.antenna From: Gene Fuller Subject: Re: Lightning Question References: <3IWdnVBwV9BTkqHeRVn-sw@crocker.com> <1128062984.923437.180830@g49g2000cwa.googlegroups.com> <1128148759.890588.276840@z14g2000cwz.googlegroups.com> Message-ID: Date: Sat, 01 Oct 2005 23:30:49 GMT I have a copy of an article that gives a good overview of the cosmic ray hypothesis. It appeared in the May 2005 issue of Physics Today. The authors are: Alexander V. Gurevich and Kirill P. Zybin. Their affiliation is described as: A.V. Gurevich is the leader and K. P. Zybin is a research scientist in the I. E. Tamm theoretical department at the P. N. Lebedev Physical Institute of the Russian Academy of Sciences in Moscow. I can e-mail a PDF copy (about 250 kB) of the article to anyone who wants one. Send me a message by correcting the rather obvious munge in my e-mail address. As I noted previously, I do not have any particular expertise or vested interest in this cosmic theory, but I do find it interesting. 73, Gene W4SZ nm5k@wt.net wrote: > > > Has nothing to do with cosmic radiation, black holes, etc.. > If that were the case, you would have near constant lightning, > in all kinds of weather. I have no doubt that lightning effects > the ultra high altitudes with the jet and sprites, etc. But I think > it starts from the strike itself, and effects upwards as some kind > of large recharge/discharge mechanism. But thats just my guess. > I really haven't looked into that much. How this guy thinks cosmic > radiation is the key, I dunno... Hummm... Is he a doktor with letters > > after his name? He's not working off a government grant is he? > Inquiring minds wanna know... > MK > Article: 217956 of rec.radio.amateur.antenna From: Walter Maxwell Subject: Re: Small, non-resonant, horiz. loop. was Re: Magnetic Loop !!! Message-ID: References: <433D46F0.D0533E2B@shaw.ca> <433D7754.F019C9B2@shaw.ca> <11jrte940qbbf67@corp.supernews.com> <11jsujdpigc5dff@corp.supernews.com> <11jtdf05htl4j4a@corp.supernews.com> Date: Sat, 01 Oct 2005 19:39:27 -0400 On Sat, 1 Oct 2005 19:33:49 +0000 (UTC), "Reg Edwards" wrote: >======================================= >Everybody has heard of the State of Michigan with its capital city of >Detroit. I have always thought of it as an industrial state similar to >my own area of the city of Birmingham and the surrounding Black >Country of England. It is the manufacuring areas which produce the >REAL wealth of this World of ours. Not forgetting the farmers. >Reg, G4FGQ. > Reg, I grew up in Michigan, and spend 6 mo a year here, the other 6 in Florida. In all the time I've spent in Michigan I wasn't aware that Detroit is the Capitol. When was it moved from Lansing? Perhaps Mac can help you out in this dilemma you're creating. Walt Article: 217957 of rec.radio.amateur.antenna From: "J. Mc Laughlin" Subject: Re: Small, non-resonant, horiz. loop. was Re: Magnetic Loop !!! Date: Sat, 1 Oct 2005 20:41:45 -0400 Message-ID: <11jub2qsovg9gae@corp.supernews.com> References: <433D46F0.D0533E2B@shaw.ca> <433D7754.F019C9B2@shaw.ca> <11jrte940qbbf67@corp.supernews.com> <11jsujdpigc5dff@corp.supernews.com> <11jtdf05htl4j4a@corp.supernews.com> Dear Reg (G4FGQ): It is now likely to be past your bed time so this message may be contemplated in the bright, clear morning. I have inserted some items below. -- J. Mc Laughlin; Michigan U.S.A. Home: JCM@Power-Net.Net "Reg Edwards" wrote in message news:dhmoat$hip$1@nwrdmz02.dmz.ncs.ea.ibs-infra.bt.com... > > "J. Mc Laughlin" wrote > > > Dear Reg (G4FGQ): > > > > I note with interest that your note was written in the early > afternoon. > > ========================================== > My Dear J. Mc Laughlin, > > Thank you for your interest in my early afternoon state of health. It > is now 19.15 hours and I have just started on a bottle of Sierra > Valley, Californian, Ruby Cabernet. --- You are commended for your assistance of our unfortunate brethren in California. A good Midwesterner gives thanks at frequent intervals not to be in crammed into California or out East. It is appropriate to observe that the French would have no good grapes were it not for the Californian growers. > > > > The subject of my communication is: small (much smaller than a > > wavelength) - non-resonant (input impedance almost entirely > inductive if one > > looks into a single opening in the loop) - horizontal - loop antenna > (no > > substances with significant magnetic properties are in the vicinity > of the > > loop antenna) - used to receive incident EM waves (which have both E > and H > > components). SNRHL receiving antennas > > > > I do not know the definition of a "magloop." Apparently, such a > beastie > > comprises a resonant loop antenna. > > ======================================= > "Magloop" describes a small, single-turn, thick conductor, usually > made from copper water pipe, circular, hexagonal or square in shape, > loop. The two ends of the loop are connected together via a variable > capacitor. The capacitor tunes the inductance of the loop to a > resonant frequency at which everything happens. > > The term "magnetic" arises because the near-field of a transmitting > loop is mainly magnetic as distinct from the electric field. On > receive it is more sensitive the magnetic field than the electric > field. --- I am obliged to you for providing a definition of "magloop." The critical element of the definition seems to be that a magloop is a loop that is resonated by a reactance. --- I am puzzled by your observation with respect to the term "magnetic" in conjunction with a loop antenna (presumably a loop antenna, whether or not a magloop). You appear to be saying that a loop antenna is more sensitive to the H field than to the E field of an incident EM field. --- Relative to you, I have only been dealing with antennas a short 50 years. However, in that time, I have only encountered antennas that extract a signal from an EM field where the ratio of E to H is well established. My graduate professor, who recently passed away and who wrote The Book on antennas, never mentioned antennas that inherently were sensitive to one component of the incident EM wave. --- Perhaps what you were saying is that one can predict the polarization of an EM wave launched from a loop antenna from knowing its geometry and the observer's orientation with respect to the geometry. This is also true for a doublet and a number of other antennas. > ======================================= > > > No knowledgeable person would disagree that a single tuned > network with > > a Q of 1000 is "narrow." > > > > My interest in SNRHL receiving antennas comes from an interest > in > > practical HF receiving antennas that are resistive to types of noise > that > > appear only to be present at isolated, open, rural, > otherwise-low-noise > > sites. The noise involved does not occur in urban areas or even > rural sites > > with many trees. > > ===================================== > The noise in rural, open, oceanic areas is just the same sort as in > built-up, residential, city and industrial areas. It is all random but > there is just a lot less of it. --- I do not have the verbal skill of Richard Clark, who could find an elegant way to say what needs to be said. Dear Reg, you are wrong. You are wrong because your long and extensive carrier has not placed you in the sites described. Had you spent time out in the sticks, bare of same, you would have encountered the discharging of charged particles into the antenna you were using (or discharging into nearby conductors) producing a prodigious amount of excess noise. The particles are sometimes dust particles, sometimes water droplets, and sometime snow. By far, the greatest limitation on the performance of an HF receiving site in rural, open country is the sudden appearance of this noise. Even at VHF, it is sometimes a limiting factor. State Police posts in Michigan have sometimes not been able to communicate with 100 watt mobiles that were less than 300 meters away because of this noise appearing in a snow storm. (Movement to much higher frequencies and other strategies have alleviated their problem.) --- My experience does not extend to extensive receiving sites out to sea. They might, it they exist at all, not encounter the excess noise. It is also clear that high air humidity may serve to reduce the excess noise. --- Please add to your vast reservoir of knowledge something new. --- > > An antenna of any sort is just as sensitive to noise as it is to > signals provided both noise and signals are coming from the same > direction and elevation. > ====================================== > > > > Consider some of the excellent wine from Michigan this evening. > This > > state, with a coastline almost the same length as that of the island > of > > Great Britain, produces some excellent products for your enjoyment. > > > ======================================= > Everybody has heard of the State of Michigan with its capital city of > Detroit. I have always thought of it as an industrial state similar to > my own area of the city of Birmingham and the surrounding Black > Country of England. It is the manufacuring areas which produce the > REAL wealth of this World of ours. Not forgetting the farmers. --- Well said! Michigan has had the most productive industry in the world. It also has some of the most productive agricultural land - especially for being in the north. However, Michigan (and others) are going through a major change. The advent of fast, inexpensive communication and transportation have seen the movement of vast numbers of manufacturing jobs to areas where wages are low. Many square miles of factories have been pulled-down to bare ground. (Taxes are thus reduced - often next to impossible to sell the land because of unknown pollutants from 90 or more of industrial use.) Ascendant in Michigan are jobs that produce intellectual property, that are involved with higher education, and that are involved with medicine including research. The new worker is different. --- While Detroit is still the largest city, the capital is in Lansing. > > Never having had the opportunity to visit Michigan it has not occurred > to me that the land could also grow grapes and produce wine. > (Actually, we do produce respectable wine here in cool-climate > industrial England. But not much of it.) ---Michigan is almost surrounded by very large lakes that mollify the weather. The west coast of Michigan, in particular, has very productive fruit farming. It is quite possible that few of Michigan's grape products are exported. Thank you for considering another of our products for your evening repast. > > It is now 20.00 hrs and too late to go shopping at my local > super-market. Nevertherless, at my next visit I shall keep my eyes > open for "Michigan" on the wine bottle labels. > ---- > Reg, G4FGQ. > > Article: 217958 of rec.radio.amateur.antenna From: Buther Boy Subject: Where to by random wire (longwire) antennas Date: Sat, 01 Oct 2005 19:59:22 -0500 Message-ID: <90cuj1pqh9pmiemvrl80tq6skp0vrpgg6d@4ax.com> I'm looking at the MFJ-16010, and want to buy some random wire and do some antenna experimenting. Could someone please point me to a link(s) for random wire antennas? Buther Boy -- Remove the word Spam from my e-mail to contact me... http://www.PrivacySig.com/SIGbutherboySpam-gmail-black.png ~ Article: 217959 of rec.radio.amateur.antenna From: Buther Boy Subject: Re: Where to by random wire (longwire) antennas Date: Sat, 01 Oct 2005 20:03:20 -0500 Message-ID: References: <90cuj1pqh9pmiemvrl80tq6skp0vrpgg6d@4ax.com> On Sat, 01 Oct 2005 19:59:22 -0500, Buther Boy wrote: >I'm looking at the MFJ-16010, and want to buy some random wire and do >some antenna experimenting. Could someone please point me to a >link(s) for random wire antennas? > >Buther Boy Also, as I am just getting back into the hobby, I need a refresher of sorts. What do I need to buy besides the random wire and antenna tuner. Are there any other supplies that are necessary (besides the radio LOL)? Thanks. Buther Boy -- Remove the word Spam from my e-mail to contact me... http://www.PrivacySig.com/SIGbutherboySpam-gmail-black.png ~ Article: 217960 of rec.radio.amateur.antenna From: mensch90249@yahoo.com Subject: Re: Where to by random wire (longwire) antennas Date: Sat, 01 Oct 2005 18:13:25 -0700 Message-ID: References: <90cuj1pqh9pmiemvrl80tq6skp0vrpgg6d@4ax.com> On Sat, 01 Oct 2005 20:03:20 -0500, Buther Boy wrote: >On Sat, 01 Oct 2005 19:59:22 -0500, Buther Boy wrote: > >>I'm looking at the MFJ-16010, and want to buy some random wire and do >>some antenna experimenting. Could someone please point me to a >>link(s) for random wire antennas? >> >>Buther Boy > >Also, as I am just getting back into the hobby, I need a refresher of >sorts. What do I need to buy besides the random wire and antenna >tuner. Are there any other supplies that are necessary (besides the >radio LOL)? > >Thanks. > >Buther Boy My recommendation is to hold off on the MFJ 'tuner' and first put up the antenna and see how it plays. As to where to buy; Lowe's, Home Depot or whatever similar type place will be your best bet for the wire - suggest #12 or #14 stranded just as you would use to wire your house. Insulators can be made from wood, use some 3/4 square cut 3 - 5 inches long with a hole drilled in each end then seal it with several coats of varnish. For more info this article is highly recommended: http://www.anarc.org/naswa/badx/antennas/low-noise_antenna.html Good Luck, Howard Article: 217961 of rec.radio.amateur.antenna From: Buther Boy Subject: Re: Where to by random wire (longwire) antennas Date: Sat, 01 Oct 2005 20:30:52 -0500 Message-ID: References: <90cuj1pqh9pmiemvrl80tq6skp0vrpgg6d@4ax.com> Howard: I read the article, and would really appreciate it if you would please simplify construction AND installation for me. Step by step, where applicable and if possible. Many thanks in advance. :-) Buther Boy On Sat, 01 Oct 2005 18:13:25 -0700, mensch90249@yahoo.com wrote: >On Sat, 01 Oct 2005 20:03:20 -0500, Buther Boy wrote: > >>On Sat, 01 Oct 2005 19:59:22 -0500, Buther Boy wrote: >> >>>I'm looking at the MFJ-16010, and want to buy some random wire and do >>>some antenna experimenting. Could someone please point me to a >>>link(s) for random wire antennas? >>> >>>Buther Boy >> >>Also, as I am just getting back into the hobby, I need a refresher of >>sorts. What do I need to buy besides the random wire and antenna >>tuner. Are there any other supplies that are necessary (besides the >>radio LOL)? >> >>Thanks. >> >>Buther Boy > >My recommendation is to hold off on the MFJ 'tuner' and first put up >the antenna and see how it plays. As to where to buy; Lowe's, Home >Depot or whatever similar type place will be your best bet for the >wire - suggest #12 or #14 stranded just as you would use to wire your >house. Insulators can be made from wood, use some 3/4 square cut 3 - >5 inches long with a hole drilled in each end then seal it with >several coats of varnish. For more info this article is highly >recommended: >http://www.anarc.org/naswa/badx/antennas/low-noise_antenna.html > >Good Luck, >Howard -- Remove the word Spam from my e-mail to contact me... http://www.PrivacySig.com/SIGbutherboySpam-gmail-black.png ~ Article: 217962 of rec.radio.amateur.antenna From: "Pat Stevens" References: <1jepj1p4qngh1ivp6bo4c1rc3vulugi6d5@4ax.com> <8bgpj11ofckhvd5dcg0umujbqav3508g9m@4ax.com> <0h0rj1ho78qtofjckgk0nrrqu4mgn8di5k@4ax.com> <2ym%e.16419$Xl2.3609@twister.nyroc.rr.com> <021sj1hb84shphia0dq78pl55r0q65sntl@4ax.com> <7d3a5$433e926c$97d558d8$32550@ALLTEL.NET> <8b50$433f1398$97d558d8$27686@ALLTEL.NET> Subject: Re: "Hams to the Rescue After Katrina" MSNBC News Article Message-ID: Date: Sun, 02 Oct 2005 01:57:05 GMT Ok. So, you were the bully who couldn't follow rules and believe that they never apply to you. So, now you are continuing that ideology in life as you "hide behind your keyboard." Just goes to show, that some people never grow up and never change. "Fred W4JLE" wrote in message news:8b50$433f1398$97d558d8$27686@ALLTEL.NET... > Nah, I used to beat the crap out of wooses like you and take their lunch > money. Enjoyed watching them cry. > > If I were standing in front of you, you would be peeing your pants and > hollering "Mommy". Your type is only brave when behind a teacher or a > keyboard. > > Get a life or get educated enough to use your newsreader correctly so you > may avoid apoplexy... > > > "Pat Stevens" wrote in message > news:Qby%e.16485$Xl2.3691@twister.nyroc.rr.com... >> You probably call the police a nazi, too, when they pull you over for >> speeding. How come everyone believes that they don't need to follow the >> rules and that when they have it pointed out to them that they are >> outside >> the rules, they are being "picked on." Is that what you were in school? >> >> "Fred W4JLE" wrote in message >> news:7d3a5$433e926c$97d558d8$32550@ALLTEL.NET... >> >I bet you were a hall monitor in school... >> > >> > It must be really boring to have a life that is only enriched by being >> > a >> > net >> > Nazi. >> >> > > Article: 217963 of rec.radio.amateur.antenna From: "Pat Stevens" References: <1jepj1p4qngh1ivp6bo4c1rc3vulugi6d5@4ax.com> <8bgpj11ofckhvd5dcg0umujbqav3508g9m@4ax.com> <0h0rj1ho78qtofjckgk0nrrqu4mgn8di5k@4ax.com> Subject: Re: "Hams to the Rescue After Katrina" MSNBC News Article Message-ID: Date: Sun, 02 Oct 2005 01:59:35 GMT The controls have already been put in place. The idea of posting on-topic is nothing new and most people find a way to keep themselves within those boundaries. I would imagine that the band plans for the amateur radio frequencies are only a "guide" for you, too, and that you feel that you can transmit in any mode and on any band that you feel fit. Right? "Mike Coslo" wrote in message news:MYSdnVOhLKEzcaPeRVn-gw@adelphia.com... > Matt Osborn wrote: >> On Sat, 01 Oct 2005 00:30:04 GMT, "Pat Stevens" >> wrote: >> >> >>> Your own stupidity is hindering you. Take it to e-mail, moron. >>> >>> wrote in message >>>news:d0krj158a9aifpk3s92eovrr0nupp0mo1u@4ax.com... >>> >>>>Simply avoiding the question? Your blindness hinders me not. >>>> >>>> >>>>-- msosborn at msosborn dot com >> >> >> Nice vocabulary. Need help using your newsreader? > > Pat doesn't like us talking about this, Matt. Seems like everyone is > having a good time, and the posts are pretty civil. I guess some people > like to control others, eh? > > - Mike KB3EIA - Article: 217964 of rec.radio.amateur.antenna From: Buther Boy Subject: Has anyone any experiences with B&W's AP-10A 300 watt portable antenna? Date: Sat, 01 Oct 2005 21:09:27 -0500 Message-ID: It is supposed to work on 2-40 meters, and is located on page 83 of HRO's (hamradio.com) online PDF catalog. Buther Boy -- Remove the word Spam from my e-mail to contact me... http://www.PrivacySig.com/SIGbutherboySpam-gmail-black.png ~ Article: 217965 of rec.radio.amateur.antenna From: "Fred W4JLE" References: <1jepj1p4qngh1ivp6bo4c1rc3vulugi6d5@4ax.com> <8bgpj11ofckhvd5dcg0umujbqav3508g9m@4ax.com> <0h0rj1ho78qtofjckgk0nrrqu4mgn8di5k@4ax.com> <2ym%e.16419$Xl2.3609@twister.nyroc.rr.com> <021sj1hb84shphia0dq78pl55r0q65sntl@4ax.com> <7d3a5$433e926c$97d558d8$32550@ALLTEL.NET> <8b50$433f1398$97d558d8$27686@ALLTEL.NET> Subject: Re: "Hams to the Rescue After Katrina" MSNBC News Article Date: Sat, 1 Oct 2005 22:23:04 -0400 Message-ID: <55b0c$433f44ba$97d558d8$25020@ALLTEL.NET> Do I look like I am "hiding" you twit! I can see not only are you too stupid to use a newsreader, in addition you have no clue as to what can be gleaned from my call. I love upsetting supercillious net Nazis. Makes my day. "Pat Stevens" wrote in message news:R7H%e.17307$Xl2.9545@twister.nyroc.rr.com... > Ok. So, you were the bully who couldn't follow rules and believe that they > never apply to you. So, now you are continuing that ideology in life as you > "hide behind your keyboard." Article: 217966 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Fractal Antennas References: <1127500565.002715.196800@o13g2000cwo.googlegroups.com> <6muij11sgp4h5hj9u39ndqfir0cocpvkf0@4ax.com> <8fblj1ho8ej0ihucalee6comabmo87h1b3@4ax.com> <11jmc9on86rvfcc@corp.supernews.com> <73063$433c14ac$97d56a13$3806@ALLTEL.NET> Message-ID: Date: Sun, 02 Oct 2005 02:50:16 GMT Mike Coslo wrote: > Indeed. But it is such a misleading term. It gets people to believe > that an antenna which is very inefficient, yet have a low "takeoff > angle" is somehow superior to an antenna that may have a higher TOA, but > may have more overall "oomph" at the same angle as the lower TOA antenna. I agree that it would have been nice if TOA had not been defined that way. What I always attempt to do is state a gain to go with the TOA. -- 73, Cecil http://www.qsl.net/w5dxp Article: 217967 of rec.radio.amateur.antenna Date: Sat, 01 Oct 2005 21:31:28 -0500 From: Tom Ring Subject: Re: "Hams to the Rescue After Katrina" MSNBC News Article References: <1jepj1p4qngh1ivp6bo4c1rc3vulugi6d5@4ax.com> <8bgpj11ofckhvd5dcg0umujbqav3508g9m@4ax.com> <0h0rj1ho78qtofjckgk0nrrqu4mgn8di5k@4ax.com> <433de88a$0$32196$39cecf19@news.twtelecom.net> Message-ID: <433f4680$0$32207$39cecf19@news.twtelecom.net> Mike Coslo wrote: > Tom Ring wrote: > >> Richard Clark wrote: >> >>> The question? "What is 6 times 7?" >>> >> >> The question, quoted from the book, is "What do you get when you >> multiply six by nine?". And the answer is still 42. Which is obvious. > > > But pi is exactly 3 in some circles....... > > While we are busy putting "intelligent design" into schools, I > suggest we start putting "faith based mathematics" in next. > > - Mike KB3EIA - That wasn't my point. I thought some of you might figure out why. I am quite disappointed to tell the truth. 6 x 9 = 42 It's not that tough, unless you can't think out of at least one box. And those that figured it out fron "The Book", please do not comment. tom K0TAR Article: 217968 of rec.radio.amateur.antenna From: "KØHB" References: <1jepj1p4qngh1ivp6bo4c1rc3vulugi6d5@4ax.com> <8bgpj11ofckhvd5dcg0umujbqav3508g9m@4ax.com> <0h0rj1ho78qtofjckgk0nrrqu4mgn8di5k@4ax.com> Subject: Re: "Hams to the Rescue After Katrina" MSNBC News Article Message-ID: Date: Sun, 02 Oct 2005 02:37:19 GMT "Pat Stevens" wrote > The controls have already been put in place. The idea of posting on-topic is > nothing new and most people find a way to keep themselves within those > boundaries. Pat, usenet has no controls "put in place" (except on moderated newsgroups). Each newsgroup is commissioned for a stated purpose and should generally be followed, but sometimes the exhuberance of the moment causes us to stray off into other areas. S#!t happens! > I would imagine that the band plans for the amateur radio frequencies are only > a "guide" for you, too, and that you feel that you can transmit in any mode > and on any band that you feel fit. Right? Bandplans are voluntary "guides", and generally make good sense. Times happen, however, when there are good reasons to deviate from a particualr bandplan. So long as the mode/band is FCC-legal and I have a personally-acceptable reason, you're right --- I >>do<< feel that I can take a one-time exception to the bandplan guidelines. 73, de Hans, K0HB Article: 217969 of rec.radio.amateur.antenna From: mensch90249@yahoo.com Subject: Re: Where to by random wire (longwire) antennas Date: Sat, 01 Oct 2005 20:55:22 -0700 Message-ID: <4rluj11u09d3f8fnjsrdgq8f191gjc4sl8@4ax.com> References: <90cuj1pqh9pmiemvrl80tq6skp0vrpgg6d@4ax.com> On Sat, 01 Oct 2005 20:30:52 -0500, Buther Boy wrote: >Howard: > >I read the article, and would really appreciate it if you would please >simplify construction AND installation for me. Step by step, where >applicable and if possible. > >Many thanks in advance. :-) > >Buther Boy Buther, I'm going to refer you to another website that has further explained it and offers some illustrations - a picture is worth....... Yes, it's a bit of laziness on my part and also an admission that I'm not so hot at writing instructions. A few tips though: 1) Insulators; wire antenna attached to one hole, rope to the other - the rope ties off to a support such as a mast, tree or house. 2) Lead in wire/transmission line; the wire can come directly to the house but can pick up lots of noise, using coaxial cable (and a suitable ground) can help reduce this - attach the center conductor to the antenna and the shield (braided wire just under the plastic jacket) to ground. if for listening only go ahead and use 75 ohm cable as you would buy for your cable or satellite TV system. 3) Ground; a metal rod, typically 8 feet long, driven into the ground; you can use the ground rod for your home electrical. 4) Keep your antenna as far from power lines as you can and perpendicular to the power lines (if nearby) can help to reduce noise vs parallel to them. Here's the site promised: http://www.kc7nod.20m.com/random_wire.htm Thanks to KC7NOD for taking the time to put this info on his site. Also, don't forget that Google is your friend, type in 'random wire antenna' and you will receive a wealth of other info. Howard Article: 217970 of rec.radio.amateur.antenna From: "Lee" References: <433D46F0.D0533E2B@shaw.ca> <433D7754.F019C9B2@shaw.ca> <11jrte940qbbf67@corp.supernews.com> <11jsujdpigc5dff@corp.supernews.com> Subject: Re: Magnetic Loop !!! Message-ID: <%GJ%e.37888$VI6.3384@fe1.news.blueyonder.co.uk> Date: Sun, 02 Oct 2005 04:51:07 GMT "Owen Duffy" wrote in message news:ntttj1to6mofbfp7q25gvu7ogbgcvmhrot@4ax.com... > On Sat, 01 Oct 2005 13:42:40 GMT, "Lee" > wrote: > > > >I took my little 1 meter dia ( 10 ft circ ) loop outside lunchtime and > >mounted it verticaly 2ft off the lawn and tested it, not expecting anything > > Did your "little loop" grow since your first post... it was 1m in > circumfrence in the beginning? > > Owen > -- You`re right Owen, i did state that didn`t i?...it was a typo of course,Heh heh, it should read "10Foot circumference approx 1 meter dia"....... Thanks for telling me ...... Lee......G6ZSG........ Article: 217971 of rec.radio.amateur.antenna From: "Lee" References: <433D46F0.D0533E2B@shaw.ca> <433D7754.F019C9B2@shaw.ca> <11jrte940qbbf67@corp.supernews.com> <11jsujdpigc5dff@corp.supernews.com> Subject: Re: Magnetic Loop !!! Message-ID: Date: Sun, 02 Oct 2005 05:27:08 GMT "Reg Edwards" wrote in message news:dhmhfg$chb$1@nwrdmz01.dmz.ncs.ea.ibs-infra.bt.com... > Hello Lee, > > Thanks for letting me know that by giving your magloop half-a-chance > it performs according to expectations. > > You have also demonstrated that the G5RV is not so hot as it is made > out to be by salesmen and they who have never tried anything else. Are you using the small internal coupling loop, about 1/5 diameter of > main loop, to match to a 50-ohm feedline? This is the best and most > simple way to go, No. i`m using a `gamma` match, if you can call it that....the matching loop comes next. Wonder if a coaxial gamma match would work as i`m a staunch believer....(could put that principle to use for the capacitor tuning instead of a butterfly variable......) Can`t get on with other types of loading, too fiddly!. Regards.... Lee...G6ZSG....... > > A different ratio small loop diameter is needed for other feedline > impedances. The circuit behaves as if the turns ratio on a > transformer is being changed. > > Let us know how your experiments proceed. > ---- > Reg, G4FGQ. > > Article: 217972 of rec.radio.amateur.antenna From: "Lee" References: <433D46F0.D0533E2B@shaw.ca> <433D7754.F019C9B2@shaw.ca> <11jrte940qbbf67@corp.supernews.com> <11jsujdpigc5dff@corp.supernews.com> Subject: Re: Magnetic Loop !!! Message-ID: <6wK%e.38996$VI6.27383@fe1.news.blueyonder.co.uk> Date: Sun, 02 Oct 2005 05:47:46 GMT "LT" wrote in message news:Xns96E28DF5645D2groupgroupcom@216.168.3.50... > Hi Lee, > > I'm a little confused about the bandwidth that you're getting. Maybe it > can be attributed to losses which widen the SWR bandwidth. That's not > necessarily a bad thing. I have used an AEA IsoLoop antenna that is > about the same size as your loop antenna but has a low loss butterfly > capacitor for tuning 10-30 MHz. On 20 meters the bandwidth is only about > 20 or 30KHz(can't remember exactly since I haven't used it for a couple > of years). It works great if you park yourself on a frequency but it is > a pain to use for hunt and pounce. Yes, of course that should have read 2.5 : 1 SWR which is better than my `loaded` half size G5RV on 80 at about 100kcs 2.5 : 1 SWR....... > > Besides the null using vertical polarization, is it possible that for > your local friend you may have been cross-polarized. Usually direct wave > cross-polarization is on the order 20db which accounts for the 2 to 3 S > units of change from vertical to horizontal. My `friend has a quarter wave vertical for 20 and the loop was physically vertical ....also, my G5RV is sloping...... > > Have fun with your new toy! Thanks, i am...... ;-) Lee....G6ZSG...... > > 73 LT <7iHZe.260$Aw.4524@typhoon.sonic.net> <73mlj158ae210i2vutdik3hg5t0987jlsn@4ax.com> From: Rockinghorse Winner Message-ID: Date: Sun, 02 Oct 2005 05:52:50 GMT Bob Miller writes: >On Wed, 28 Sep 2005 14:14:51 GMT, Cecil Moore wrote: >>Bob Miller wrote: >>> The instruction book I got with my mfj 989c tuner has a section on >>> ladder line lengths to gravitate to, or avoid, depending on band. It >>> can be downloaded free from the mfj web site. >> >>Hopefully, the lengths to avoid are associated with specific >>loads. Avoiding 1/4WL of ladder-line when feeding a 1/2WL >>dipole may be good advice but 1/4WL of ladder-line is ideal >>for feeding a one wavelength dipole. >They're fairly specific about loads -- their manual is at >http://www.mfjenterprises.com/products.php?prodid=MFJ-989C with pages >7 and 8 talking about feedline lengths. >bob >k5qwg Wow! I'll have a look a this ASAP. -- R*Horse rwinner.blogspot.com Article: 217974 of rec.radio.amateur.antenna From: "Reg Edwards" Subject: Re: Magnetic Loop !!! Date: Sun, 2 Oct 2005 06:38:26 +0000 (UTC) Message-ID: References: <433D46F0.D0533E2B@shaw.ca> <433D7754.F019C9B2@shaw.ca> <11jrte940qbbf67@corp.supernews.com> <11jsujdpigc5dff@corp.supernews.com> > What about a fractal magloop Reg? Should be even smaller. :>) > This is a case of a fractal GUARANTEED to perform worse than the basic antenna in all respects. That is unless a simple circle can be considered to be a zero-zero-order fractal. Article: 217975 of rec.radio.amateur.antenna From: David Subject: Tables of Er for various metal tubes ? Message-ID: <0xL%e.4865$U51.3234@news-server.bigpond.net.au> Date: Sun, 02 Oct 2005 06:57:00 GMT Does anyone know where I can find Er tables for various type and diameter of metal tubing so I can calculate Velocity coefficient Vp ? Thanks in advance Regards David Article: 217976 of rec.radio.amateur.antenna From: David Subject: Help with Sleeve Dipole Message-ID: Date: Sun, 02 Oct 2005 07:16:01 GMT I am a little confused with calculation of appropriate length of metal tubing used in a sleeve antenna design (the 1/4 wave section). I understand that as RF travels through various mediums, Velocity of the wave slows down relative to Er of the material. So for coax the wavelength would be say 0.66 Lambda. With the tubing over a coaxial cable though it seems there is Vp related to the dielectric formed between the sleeve and the outer sheath of the coax cable but also the Metal has an Er value. 1. Do you need to count for both these when calculate how the tube should be. 2. Is there relationship that needs to be considered between sleeve length and distance between sleeve and coax (ie. If the sleeve is made larger diameter does it effect the length required for the tube or is this still defined strictly by Er) also, Does the diameter of the tube effect the impedance ? The specific example is RG174 Coax cable vertical dipole. The top radiating element is 1/4 long. At the bottom of this element is a length of RG174 Coax. 1/4 wave length of this coax has a 5/32 Brass sleeve. The sleeve is soldered to the RG174 coax at the point where the coax meets the top 1/4 wave element. I need to understand what needs to be used to calculate the length of Brass tubing sleeve given the tubing diameter is 5/32 and besides air, the outer sheath of the RG174 is also between the sleeve and Earth braid. Is the diameter of the tubing critical (will it impact adversely on SWR looking into this antenna). The final point would be if I place some ferrite rings across the coax below the sleeve, will this improve SWR ? Thanks Regards David Article: 217977 of rec.radio.amateur.antenna From: "Reg Edwards" Subject: Re: Small, non-resonant, horiz. loop. was Re: Magnetic Loop !!! Date: Sun, 2 Oct 2005 07:54:05 +0000 (UTC) Message-ID: References: <433D46F0.D0533E2B@shaw.ca> <433D7754.F019C9B2@shaw.ca> <11jrte940qbbf67@corp.supernews.com> <11jsujdpigc5dff@corp.supernews.com> <11jtdf05htl4j4a@corp.supernews.com> Walt, We are all sentimentally attached to the area where we were born. I find it intriguing you were brought up in the same sort of industrial region as I was dragged up in. There are a few descriptive paragraphs in "A bit about Reg" in my website. Please forgive me for assuming the largest city of Detroit to be the political capital of Michigan when it is actually Lansing. Again there is a similarity. The political capital of Warwickshire is not the largest city of Birmingham but the small ancient town of Warwick with its castle, not far from Shakespeare's Stratford-upon-Avon. Is Michigan named after an Indian tribe? ---- Reg. Article: 217978 of rec.radio.amateur.antenna From: Owen Duffy Subject: Re: Magnetic Loop !!! Message-ID: <252vj1p09echnki252ss6839q778pf3rc6@4ax.com> References: <433D46F0.D0533E2B@shaw.ca> <433D7754.F019C9B2@shaw.ca> <11jrte940qbbf67@corp.supernews.com> <11jsujdpigc5dff@corp.supernews.com> <6wK%e.38996$VI6.27383@fe1.news.blueyonder.co.uk> Date: Sun, 02 Oct 2005 08:01:27 GMT On Sun, 02 Oct 2005 05:47:46 GMT, "Lee" wrote: >Yes, of course that should have read 2.5 : 1 SWR which is better than my >`loaded` half size G5RV on 80 at about 100kcs 2.5 : 1 SWR....... What is a "'loaded' half size G5RV"? Googling for info, I see a few suppliers with loading coils for a half size G5RV (complete with instructions), but could not find an article with physical dimensions and loading coil characteristics. Is this a "proprietary" antenna, not open to independent analysis. In its "normal" mode, a (full size) G5RV has feed system losses on 160m like cricket scores. Intuition suggests that a half-size G5RV (where everything is scaled to 50%) will have similarly appalling performance on 80m. Has anyone seen details of the loading coils for this "loaded half-sized G5RV', or models of its performance? Owen -- Article: 217979 of rec.radio.amateur.antenna From: David Subject: Re: Help with Sleeve Dipole References: <3d3vj1lvc8tsg4mj90euuk9shdfrecp4mc@4ax.com> Message-ID: Date: Sun, 02 Oct 2005 08:18:01 GMT Richard, Thanks for the feedback. No problem with the failing issue, plenty of that going on. The way I see it though is that if I can add some knowledge to my experimentation then at least I can "play" with some hope of moving to a solution in the right direction. Richard Clark wrote: > On Sun, 02 Oct 2005 07:16:01 GMT, David wrote: > > >>I need to understand what needs to be used to calculate the length of >>Brass tubing sleeve given the tubing diameter is 5/32 and besides air, >>the outer sheath of the RG174 is also between the sleeve and Earth >>braid. Is the diameter of the tubing critical (will it impact adversely >>on SWR looking into this antenna). > > > Hi David, > > The Er of the metal is not something that comes quickly to mind > (especially this late at night). Besides, it sounds like what you are > describing is the radial component which would be fantastically small > (many decimal places, not simply tens of percent). > > It also seems like your application is for UHF (you need to be more > specific). This makes such "calculations" little better than SWAGs. > It doesn't take much to be way off. What is even more confounding is > your problem contains a hidden trap. > > The sleeve of brass that drops below the feed point is embracing the > jacket of the RG174. THIS constitutes the dielectric constant of > interest and is a material that is different from the insulator of the > inner line. Even more, and as you note above, there is some air mixed > in to really gum up the back of the napkin calculations. This is the > G of the SWAG. > > Worst yet, some jacket material is actually quite lossy, or so it has > been reported - another G of the SWAG. > > All-in-all, what you need to do is build one and measure it. No doubt > that will lead to another trail of tears. On the other hand, there is > nothing so stimulating to learning than pain. Most of my best > subjects centered on projects I thoroughly screwed up. > > As the saying goes: > "If you haven't failed, you aren't trying hard enough." > > 73's > Richard Clark, KB7QHC Article: 217980 of rec.radio.amateur.antenna From: "Reg Edwards" Subject: Re: Small, non-resonant, horiz. loop. was Re: Magnetic Loop !!! Date: Sun, 2 Oct 2005 10:02:09 +0000 (UTC) Message-ID: References: <433D46F0.D0533E2B@shaw.ca> <433D7754.F019C9B2@shaw.ca> <11jrte940qbbf67@corp.supernews.com> <11jsujdpigc5dff@corp.supernews.com> <11jtdf05htl4j4a@corp.supernews.com> <11jub2qsovg9gae@corp.supernews.com> Michigan has had the most productive industry in the world. > It also has some of the most productive agricultural land - especially for > being in the north. However, Michigan (and others) are going through a > major change. The advent of fast, inexpensive communication and > transportation have seen the movement of vast numbers of manufacturing jobs > to areas where wages are low. Many square miles of factories have been > pulled-down to bare ground. (Taxes are thus reduced - often next to > impossible to sell the land because of unknown pollutants from 90 or more of > industrial use.) Ascendant in Michigan are jobs that produce intellectual > property, that are involved with higher education, and that are involved > with medicine including research. The new worker is different. > ========================================= Dear J. Birmingham and the Black Country has suffered a similar fate. Once upon a time EVERYTHING was made in Birmingham. I began work at the age of 14 in an electric motor factory. (I've never met a university professor.) Factories have now been converted to museums as an adjunct to the tourist trade. Only this very week, the last of the once-upon-a-time many Black Country iron foundries poured the last few tons of molten iron from its furnaces. Sadly, three months back the last of the 100-year old motor factories, which started with bicycles, closed its gates rendering 15,000 people redundent. Motor production is to continue in China. Not that I have anything against the enterprising, hard-working Chinese who bought the factory complete with the intellectual property. Good luck to 'em. The rot set in with Lady Maggie Thatcher who favoured the so-called 'service industries'. Now we have Blair who's selling off the Health Service and has loaned the British Army, free of charge, to the Americans. But we can't get rid of him until Bush has gone. Now back to, the always with us, SWR. ;o) ---- Yours, Reg. Article: 217981 of rec.radio.amateur.antenna From: "Reg Edwards" Subject: Re: Tables of Er for various metal tubes ? Date: Sun, 2 Oct 2005 10:54:25 +0000 (UTC) Message-ID: References: <0xL%e.4865$U51.3234@news-server.bigpond.net.au> "David" wrote > Does anyone know where I can find Er tables for various type and diameter > of metal tubing so I can calculate Velocity coefficient Vp ? > ===================================== The velocity factor of any conductor, including tubes, depends only on what surrounds it. If the surroundings are air, which is mainly oxygen and nitrogen, then the VF = 1.00, equivalent, in metric units, to a velocity of 300 metres per micro-second. Or in ancient, old-fashioned units, it is the far-less-convenient 669600000 miles per hour, give or take a few 100,000 miles. Who cares? --- Reg. Article: 217982 of rec.radio.amateur.antenna From: Buther Boy Subject: Re: Where to by random wire (longwire) antennas Date: Sun, 02 Oct 2005 06:59:32 -0500 Message-ID: <1pivj1dpef92l4b61vlbqe03ravkj3dfbm@4ax.com> References: <90cuj1pqh9pmiemvrl80tq6skp0vrpgg6d@4ax.com> <4rluj11u09d3f8fnjsrdgq8f191gjc4sl8@4ax.com> Howard: I somehow "dreamed" of being able to hide this random wire in my house and tune it up, but that is looking more improbable by the minute. I live in a town home and have no yard. Things don't look good, but I have an excellent idea of how this all works. I appreciate your help, Howard, and thanks for the detailed explanations. Buther Boy On Sat, 01 Oct 2005 20:55:22 -0700, mensch90249@yahoo.com wrote: >On Sat, 01 Oct 2005 20:30:52 -0500, Buther Boy wrote: > >>Howard: >> >>I read the article, and would really appreciate it if you would please >>simplify construction AND installation for me. Step by step, where >>applicable and if possible. >> >>Many thanks in advance. :-) >> >>Buther Boy > >Buther, >I'm going to refer you to another website that has further explained >it and offers some illustrations - a picture is worth....... > >Yes, it's a bit of laziness on my part and also an admission that I'm >not so hot at writing instructions. A few tips though: >1) Insulators; wire antenna attached to one hole, rope to the other - >the rope ties off to a support such as a mast, tree or house. >2) Lead in wire/transmission line; the wire can come directly to the >house but can pick up lots of noise, using coaxial cable (and a >suitable ground) can help reduce this - attach the center conductor to >the antenna and the shield (braided wire just under the plastic >jacket) to ground. if for listening only go ahead and use 75 ohm >cable as you would buy for your cable or satellite TV system. >3) Ground; a metal rod, typically 8 feet long, driven into the ground; >you can use the ground rod for your home electrical. >4) Keep your antenna as far from power lines as you can and >perpendicular to the power lines (if nearby) can help to reduce noise >vs parallel to them. > >Here's the site promised: http://www.kc7nod.20m.com/random_wire.htm >Thanks to KC7NOD for taking the time to put this info on his site. >Also, don't forget that Google is your friend, type in 'random wire >antenna' and you will receive a wealth of other info. > >Howard -- Remove the word Spam from my e-mail to contact me... http://www.PrivacySig.com/SIGbutherboySpam-gmail-black.png ~ Article: 217983 of rec.radio.amateur.antenna From: "Mike" References: <1jepj1p4qngh1ivp6bo4c1rc3vulugi6d5@4ax.com> <8bgpj11ofckhvd5dcg0umujbqav3508g9m@4ax.com> <0h0rj1ho78qtofjckgk0nrrqu4mgn8di5k@4ax.com> <2ym%e.16419$Xl2.3609@twister.nyroc.rr.com> <021sj1hb84shphia0dq78pl55r0q65sntl@4ax.com> <7d3a5$433e926c$97d558d8$32550@ALLTEL.NET> <8b50$433f1398$97d558d8$27686@ALLTEL.NET> <55b0c$433f44ba$97d558d8$25020@ALLTEL.NET> Subject: Re: "Hams to the Rescue After Katrina" MSNBC News Article Date: Sun, 2 Oct 2005 08:21:11 -0400 Message-ID: <433fd30a@news.usenetzone.com> I think he was pointing out that he is hiding about as well as you are hiding. "Fred W4JLE" wrote in message news:55b0c$433f44ba$97d558d8$25020@ALLTEL.NET... > Do I look like I am "hiding" you twit! > > I can see not only are you too stupid to use a newsreader, in addition you > have no clue as to what can be gleaned from my call. > > I love upsetting supercillious net Nazis. Makes my day. > > "Pat Stevens" wrote in message > news:R7H%e.17307$Xl2.9545@twister.nyroc.rr.com... >> Ok. So, you were the bully who couldn't follow rules and believe that > they >> never apply to you. So, now you are continuing that ideology in life as > you >> "hide behind your keyboard." > > _________________________________________ Usenet Zone Free Binaries Usenet Server More than 140,000 groups Unlimited download http://www.usenetzone.com to open account Article: 217984 of rec.radio.amateur.antenna From: David Subject: Re: Tables of Er for various metal tubes ? References: <0xL%e.4865$U51.3234@news-server.bigpond.net.au> Message-ID: Date: Sun, 02 Oct 2005 13:13:04 GMT OK, so the electrical wavelength of the tube will only be effected by the dielectric material and it does not make any difference how large the gap is between the Sleeve and the Coax ? The frequency of operation is 920 MHz. Do you happen to know what the covering is made of on the outer sheath of RG174 ? The cable I have has a stranded inner core and seems to have a PFTE dielectric. (Doesn't melt at all when soldering so I assume this is what it is). Reg Edwards wrote: > "David" wrote > >>Does anyone know where I can find Er tables for various type and > > diameter > >>of metal tubing so I can calculate Velocity coefficient Vp ? >> > > ===================================== > The velocity factor of any conductor, including tubes, depends only on > what surrounds it. > > If the surroundings are air, which is mainly oxygen and nitrogen, then > the VF = 1.00, equivalent, in metric units, to a velocity of 300 > metres per micro-second. Or in ancient, old-fashioned units, it is the > far-less-convenient 669600000 miles per hour, give or take a few > 100,000 miles. Who cares? > --- > Reg. > > Article: 217985 of rec.radio.amateur.antenna From: Bob Miller Subject: Re: Has anyone any experiences with B&W's AP-10A 300 watt portable antenna? Message-ID: References: Date: Sun, 02 Oct 2005 13:34:03 GMT On Sat, 01 Oct 2005 21:09:27 -0500, Buther Boy wrote: >It is supposed to work on 2-40 meters, and is located on page 83 of >HRO's (hamradio.com) online PDF catalog. > >Buther Boy 25 years ago, I had one in a 3rd story apartment. I mounted the whip in a window, about 20 feet up. It worked reasonably well. I was able to tune it up on all bands, including 40 meters. The key is to adjust the length of the counterpoise wire for each frequency you tune up -- I had the wire on a metal spool, and rolled or unrolled the wire till I had low SWR. That wire is hot with RF, so I had a hot wire running across the apartment rug, and you have to watch that. Since you're in a townhouse, you'll be able to ground your station, which I was not able to do in the apartment, so you'll be ahead on that count. For limited space, it's a pretty neat setup, and you can make contacts with it; not as well as with a dipole outdoors, but it works. bob k5qwg Article: 217986 of rec.radio.amateur.antenna From: Bob Miller Subject: Re: Where to by random wire (longwire) antennas Message-ID: References: <90cuj1pqh9pmiemvrl80tq6skp0vrpgg6d@4ax.com> Date: Sun, 02 Oct 2005 13:42:29 GMT On Sat, 01 Oct 2005 19:59:22 -0500, Buther Boy wrote: >I'm looking at the MFJ-16010, and want to buy some random wire and do >some antenna experimenting. Could someone please point me to a >link(s) for random wire antennas? > >Buther Boy Get your tuner, get a 500 foot roll of #14 insulated wire from Lowes or Home Depot (about $30), order a copy of the ARRL Antenna Book from their web site for the particulars on random or long wires, and you'll be all set. bob k5qwg Article: 217987 of rec.radio.amateur.antenna From: "Dave VanHorn" Subject: Vertical colinear Message-ID: <2YR%e.2887$nJ2.2349@fe73.usenetserver.com> Date: Sun, 2 Oct 2005 09:15:26 -0500 I'm a bit confused over the construction of a vertical colinear. The docs I've seen all are more or less the same, alternating half-wave sections of coax or hardline. The thing that's bending my head, is that there's a velocity factor inside the coax, that presumably isn't there on the outside. So, while a given section is a half wave on the outside, it's probably more like 3/4 wave inside. My understanding is that we are trying to get to a series of dipoles all fed in phase, and yet this seems like it's not accomplishing that. What am I missing? Article: 217988 of rec.radio.amateur.antenna From: "Caveat Lector" References: <1jepj1p4qngh1ivp6bo4c1rc3vulugi6d5@4ax.com> <8bgpj11ofckhvd5dcg0umujbqav3508g9m@4ax.com> <0h0rj1ho78qtofjckgk0nrrqu4mgn8di5k@4ax.com> <2ym%e.16419$Xl2.3609@twister.nyroc.rr.com> <021sj1hb84shphia0dq78pl55r0q65sntl@4ax.com> <7d3a5$433e926c$97d558d8$32550@ALLTEL.NET> <8b50$433f1398$97d558d8$27686@ALLTEL.NET> <55b0c$433f44ba$97d558d8$25020@ALLTEL.NET> <433fd30a@news.usenetzone.com> Subject: Re: Hams to the Rescue Message-ID: <%zS%e.17526$mH.6909@fed1read07> Date: Sun, 2 Oct 2005 07:58:08 -0700 To get back to the subject title -- take a look at this excellent website http://www.wx4nhc.org/ -- CL -- I doubt, therefore I might be ! Article: 217989 of rec.radio.amateur.antenna From: "Fred W4JLE" References: <1jepj1p4qngh1ivp6bo4c1rc3vulugi6d5@4ax.com> <8bgpj11ofckhvd5dcg0umujbqav3508g9m@4ax.com> <0h0rj1ho78qtofjckgk0nrrqu4mgn8di5k@4ax.com> <2ym%e.16419$Xl2.3609@twister.nyroc.rr.com> <021sj1hb84shphia0dq78pl55r0q65sntl@4ax.com> <7d3a5$433e926c$97d558d8$32550@ALLTEL.NET> <8b50$433f1398$97d558d8$27686@ALLTEL.NET> <55b0c$433f44ba$97d558d8$25020@ALLTEL.NET> <433fd30a@news.usenetzone.com> Subject: Re: "Hams to the Rescue After Katrina" MSNBC News Article Date: Sun, 2 Oct 2005 11:21:21 -0400 Message-ID: <26afc$433ffb24$97d558d8$6525@ALLTEL.NET> I don't really care, he bores me with his Damyankee, liberal attitude. If there are no rules to control your every move, they will make up some, and get then upset when you don't follow them. "Mike" wrote in message news:433fd30a@news.usenetzone.com... > I think he was pointing out that he is hiding about as well as you are > hiding. > "Fred W4JLE" wrote in message > news:55b0c$433f44ba$97d558d8$25020@ALLTEL.NET... > > Do I look like I am "hiding" you twit! > > > > I can see not only are you too stupid to use a newsreader, in addition you > > have no clue as to what can be gleaned from my call. > > > > I love upsetting supercillious net Nazis. Makes my day. > > > > "Pat Stevens" wrote in message > > news:R7H%e.17307$Xl2.9545@twister.nyroc.rr.com... > >> Ok. So, you were the bully who couldn't follow rules and believe that > > they > >> never apply to you. So, now you are continuing that ideology in life as > > you > >> "hide behind your keyboard." > > > > > > > _________________________________________ > Usenet Zone Free Binaries Usenet Server > More than 140,000 groups > Unlimited download > http://www.usenetzone.com to open account Article: 217990 of rec.radio.amateur.antenna From: "Pat Stevens" References: <1jepj1p4qngh1ivp6bo4c1rc3vulugi6d5@4ax.com> <8bgpj11ofckhvd5dcg0umujbqav3508g9m@4ax.com> <0h0rj1ho78qtofjckgk0nrrqu4mgn8di5k@4ax.com> <2ym%e.16419$Xl2.3609@twister.nyroc.rr.com> <021sj1hb84shphia0dq78pl55r0q65sntl@4ax.com> <7d3a5$433e926c$97d558d8$32550@ALLTEL.NET> <8b50$433f1398$97d558d8$27686@ALLTEL.NET> <55b0c$433f44ba$97d558d8$25020@ALLTEL.NET> Subject: Re: "Hams to the Rescue After Katrina" MSNBC News Article Message-ID: Date: Sun, 02 Oct 2005 16:27:17 GMT Hey, Fred, Does this ring a bell? Why do you feel this group would be any different than the one you posted the following message to? Re: Man, Mr. bush Jr. sure is wicked evil eh? by "w4jle" Apr 22, 2004 at 07:13 PM Take this crap to alt.wewearaluminimum.hats Any body forwarding this much crap either is being paid to do it, or seriously needs to get a life! -- W4jle.com - Home of the Professional Curmudgeon "Fred W4JLE" wrote in message news:55b0c$433f44ba$97d558d8$25020@ALLTEL.NET... > Do I look like I am "hiding" you twit! > > I can see not only are you too stupid to use a newsreader, in addition you > have no clue as to what can be gleaned from my call. > > I love upsetting supercillious net Nazis. Makes my day. > > "Pat Stevens" wrote in message > news:R7H%e.17307$Xl2.9545@twister.nyroc.rr.com... >> Ok. So, you were the bully who couldn't follow rules and believe that > they >> never apply to you. So, now you are continuing that ideology in life as > you >> "hide behind your keyboard." > > Article: 217991 of rec.radio.amateur.antenna From: "David G. Nagel" Subject: Re: Help with Sleeve Dipole Date: Sun, 02 Oct 2005 12:03:12 -0500 Message-ID: <11k04mh9vbli6d1@corp.supernews.com> References: David wrote: > I am a little confused with calculation of appropriate length of metal > tubing used in a sleeve antenna design (the 1/4 wave section). > > I understand that as RF travels through various mediums, Velocity of the > wave slows down relative to Er of the material. So for coax the > wavelength would be say 0.66 Lambda. > > With the tubing over a coaxial cable though it seems there is Vp related > to the dielectric formed between the sleeve and the outer sheath of the > coax cable but also the Metal has an Er value. > > 1. Do you need to count for both these when calculate how the tube > should be. > 2. Is there relationship that needs to be considered between sleeve > length and distance between sleeve and coax (ie. If the sleeve is made > larger diameter does it effect the length required for the tube or is > this still defined strictly by Er) also, Does the diameter of the tube > effect the impedance ? > > The specific example is RG174 Coax cable vertical dipole. The top > radiating element is 1/4 long. At the bottom of this element is a length > of RG174 Coax. 1/4 wave length of this coax has a 5/32 Brass sleeve. The > sleeve is soldered to the RG174 coax at the point where the coax meets > the top 1/4 wave element. > I need to understand what needs to be used to calculate the length of > Brass tubing sleeve given the tubing diameter is 5/32 and besides air, > the outer sheath of the RG174 is also between the sleeve and Earth > braid. Is the diameter of the tubing critical (will it impact adversely > on SWR looking into this antenna). > > The final point would be if I place some ferrite rings across the coax > below the sleeve, will this improve SWR ? > > Thanks > > Regards > > David David; That's why they call it the ART of antenna design. First you make the best mathematical calculations you can then you start cutting wire/tubing. Make your lengths slightly longer than the math says then prune the lengths until the antenna works the way you think it should. There are so many variables in antennas that this is the only practical way to make a new one. Once you find your optimal lengths you can make more to the same specs. However remember that just like in housing antenna's depend on three things: location, location, location and have to be custom adjusted for each site. Dave WD9BDZ Article: 217992 of rec.radio.amateur.antenna From: "J. Mc Laughlin" Subject: Re: Small, non-resonant, horiz. loop. was Re: Magnetic Loop !!! Date: Sun, 2 Oct 2005 13:14:15 -0400 Message-ID: <11k05blgo2vgq65@corp.supernews.com> References: <433D46F0.D0533E2B@shaw.ca> <433D7754.F019C9B2@shaw.ca> <11jrte940qbbf67@corp.supernews.com> <11jsujdpigc5dff@corp.supernews.com> <11jtdf05htl4j4a@corp.supernews.com> <11jub2qsovg9gae@corp.supernews.com> Dear Reg: In both of our countries, major changes are occurring. In the truly creative sphere, the English speaking countries are still ahead. Education in the "hard" subjects is critical. Well now, Reg, you have at last met (via the Internet) an actual university professor of electrical engineering. 73, Mac N8TT -- J. Mc Laughlin; Michigan U.S.A. Home: JCM@Power-Net.Net "Reg Edwards" wrote in message news:dhob71$stq$1@nwrdmz02.dmz.ncs.ea.ibs-infra.bt.com... > Michigan has had the most productive industry in the world. > > It also has some of the most productive agricultural land - > especially for > > being in the north. However, Michigan (and others) are going > through a > > major change. The advent of fast, inexpensive communication and > > transportation have seen the movement of vast numbers of > manufacturing jobs > > to areas where wages are low. Many square miles of factories have > been > > pulled-down to bare ground. (Taxes are thus reduced - often next to > > impossible to sell the land because of unknown pollutants from 90 years or > more of > > industrial use.) Ascendant in Michigan are jobs that produce > intellectual > > property, that are involved with higher education, and that are > involved > > with medicine including research. The new worker is different. > > > ========================================= > Dear J. > > Birmingham and the Black Country has suffered a similar fate. Once > upon a time EVERYTHING was made in Birmingham. I began work at the age > of 14 in an electric motor factory. (I've never met a university > professor.) Factories have now been converted to museums as an adjunct > to the tourist trade. > > Only this very week, the last of the once-upon-a-time many Black > Country iron foundries poured the last few tons of molten iron from > its furnaces. Sadly, three months back the last of the 100-year old > motor factories, which started with bicycles, closed its gates > rendering 15,000 people redundent. Motor production is to continue in > China. Not that I have anything against the enterprising, hard-working > Chinese who bought the factory complete with the intellectual > property. Good luck to 'em. > > The rot set in with Lady Maggie Thatcher who favoured the so-called > 'service industries'. Now we have Blair who's selling off the Health > Service and has loaned the British Army, free of charge, to the > Americans. But we can't get rid of him until Bush has gone. > > Now back to, the always with us, SWR. ;o) > ---- > Yours, Reg. > > Article: 217993 of rec.radio.amateur.antenna From: "Dave VanHorn" References: <11k04mh9vbli6d1@corp.supernews.com> Subject: Re: Help with Sleeve Dipole Message-ID: Date: Sun, 2 Oct 2005 12:26:00 -0500 >> With the tubing over a coaxial cable though it seems there is Vp related >> to the dielectric formed between the sleeve and the outer sheath of the >> coax cable but also the Metal has an Er value. >From what I understand, the RF will be traveling on the outside of the sleeve, and won't "see" the internals at all. So, the sleeve ends up as a 1/4 wavelength stub. Is the diameter of the tubing critical (will it impact adversely >> on SWR looking into this antenna). It shouldn't be >> The final point would be if I place some ferrite rings across the coax >> below the sleeve, will this improve SWR ? Not if the sleeve is doing it's job. The sleeve's open end should look like a short at the operating frequency, and keep RF off the feedline. >> Thanks >> >> Regards >> >> David > David; > > That's why they call it the ART of antenna design. First you make the > best mathematical calculations you can then you start cutting wire/tubing. > Make your lengths slightly longer than the math says then prune the > lengths until the antenna works the way you think it should. > > There are so many variables in antennas that this is the only practical > way to make a new one. Once you find your optimal lengths you can make > more to the same specs. However remember that just like in housing > antenna's depend on three things: location, location, location and have to > be custom adjusted for each site. > > Dave WD9BDZ Article: 217994 of rec.radio.amateur.antenna From: "Fred W4JLE" References: <1jepj1p4qngh1ivp6bo4c1rc3vulugi6d5@4ax.com> <8bgpj11ofckhvd5dcg0umujbqav3508g9m@4ax.com> <0h0rj1ho78qtofjckgk0nrrqu4mgn8di5k@4ax.com> <2ym%e.16419$Xl2.3609@twister.nyroc.rr.com> <021sj1hb84shphia0dq78pl55r0q65sntl@4ax.com> <7d3a5$433e926c$97d558d8$32550@ALLTEL.NET> <8b50$433f1398$97d558d8$27686@ALLTEL.NET> <55b0c$433f44ba$97d558d8$25020@ALLTEL.NET> Subject: Re: "Hams to the Rescue After Katrina" MSNBC News Article Date: Sun, 2 Oct 2005 14:30:58 -0400 Message-ID: <2e4ae$43402795$97d558d8$23323@ALLTEL.NET> Did we cause you to spend two days googling newsgroups? You could have found much better examples, I have been getting after net nazis since the ARPA days. Your still a damnyankee liberal twit. "Pat Stevens" wrote in message news:FTT%e.17504$Xl2.16932@twister.nyroc.rr.com... > Hey, Fred, > Does this ring a bell? Why do you feel this group would be any different > than the one you posted the following message to? > > Re: Man, Mr. bush Jr. sure is wicked evil eh? > by "w4jle" Apr 22, 2004 at 07:13 PM > > > Take this crap to alt.wewearaluminimum.hats > > Any body forwarding this much crap either is being paid to do it, or > seriously needs to get a life! > > > -- > W4jle.com - Home of the Professional Curmudgeon > > > > > "Fred W4JLE" wrote in message > news:55b0c$433f44ba$97d558d8$25020@ALLTEL.NET... > > Do I look like I am "hiding" you twit! > > > > I can see not only are you too stupid to use a newsreader, in addition you > > have no clue as to what can be gleaned from my call. > > > > I love upsetting supercillious net Nazis. Makes my day. > > > > "Pat Stevens" wrote in message > > news:R7H%e.17307$Xl2.9545@twister.nyroc.rr.com... > >> Ok. So, you were the bully who couldn't follow rules and believe that > > they > >> never apply to you. So, now you are continuing that ideology in life as > > you > >> "hide behind your keyboard." > > > > > > Article: 217995 of rec.radio.amateur.antenna From: "Pat Stevens" References: <1jepj1p4qngh1ivp6bo4c1rc3vulugi6d5@4ax.com> <8bgpj11ofckhvd5dcg0umujbqav3508g9m@4ax.com> <0h0rj1ho78qtofjckgk0nrrqu4mgn8di5k@4ax.com> <2ym%e.16419$Xl2.3609@twister.nyroc.rr.com> <021sj1hb84shphia0dq78pl55r0q65sntl@4ax.com> <7d3a5$433e926c$97d558d8$32550@ALLTEL.NET> <8b50$433f1398$97d558d8$27686@ALLTEL.NET> <55b0c$433f44ba$97d558d8$25020@ALLTEL.NET> <2e4ae$43402795$97d558d8$23323@ALLTEL.NET> Subject: Re: "Hams to the Rescue After Katrina" MSNBC News Article Message-ID: Date: Sun, 02 Oct 2005 19:21:15 GMT No, I only spent a couple of minutes looking. I thought it was interesting that the shoe is now on the other foot, for you. Found your page interesting, too. However, I find it ironic that you call me a yankee. I have been trying to shed the southerner image here with my friends and coworkers ever since I moved up here from Myrtle Beach, after retiring from the Air Force. I grew up in Beaufort, SC, near the Naval Hospital. Most people say that I still have the accent. "Fred W4JLE" wrote in message news:2e4ae$43402795$97d558d8$23323@ALLTEL.NET... > Did we cause you to spend two days googling newsgroups? You could have > found > much better examples, I have been getting after net nazis since the ARPA > days. Your still a damnyankee liberal twit. > > > "Pat Stevens" wrote in message > news:FTT%e.17504$Xl2.16932@twister.nyroc.rr.com... >> Hey, Fred, >> Does this ring a bell? Why do you feel this group would be any different >> than the one you posted the following message to? >> >> Re: Man, Mr. bush Jr. sure is wicked evil eh? >> by "w4jle" Apr 22, 2004 at 07:13 PM >> >> >> Take this crap to alt.wewearaluminimum.hats >> >> Any body forwarding this much crap either is being paid to do it, or >> seriously needs to get a life! >> >> >> -- >> W4jle.com - Home of the Professional Curmudgeon >> >> >> >> >> "Fred W4JLE" wrote in message >> news:55b0c$433f44ba$97d558d8$25020@ALLTEL.NET... >> > Do I look like I am "hiding" you twit! >> > >> > I can see not only are you too stupid to use a newsreader, in addition > you >> > have no clue as to what can be gleaned from my call. >> > >> > I love upsetting supercillious net Nazis. Makes my day. >> > >> > "Pat Stevens" wrote in message >> > news:R7H%e.17307$Xl2.9545@twister.nyroc.rr.com... >> >> Ok. So, you were the bully who couldn't follow rules and believe that >> > they >> >> never apply to you. So, now you are continuing that ideology in life > as >> > you >> >> "hide behind your keyboard." >> > >> > >> >> > > Article: 217996 of rec.radio.amateur.antenna From: "Jerry Martes" References: <1128269672.814425.42830@g14g2000cwa.googlegroups.com> Subject: Re: Need Suggestions for a Relay Source Message-ID: <4tW%e.3427$kl3.1494@trnddc08> Date: Sun, 02 Oct 2005 19:23:44 GMT "Brian Kelly" wrote in message news:1128269672.814425.42830@g14g2000cwa.googlegroups.com... > I'm looking for a source for small inexpensive 12VDC relays which are > usable for cold-switching ~200W of RF at frequencies up to 30 Mhz. The > relays would be used to remotely select several single-band antenna > tuners and several end-fed vertical wire antennas strung up into some > tall trees. The "tuners" would be link-coupled tapped parallel tank > ciruits, one tuner per band. > > There would be two relays needed per band, one to switch the 50 ohm > coax from the shack to the specific tuner and the other at the output > end of the tuner to select the particular wire. At the input ends of > the tuners the RF voltage would be around 200V @ 2 amps. At the output > ends of the tuners (depending on the feedpoint impedance) the RF > voltage could go into the 2kV range at very low currents. So basically > I need some sort of relays which can handle 2kV of HF RF at 2 amps. > Single pole NO non-latching reed switches would do the job. > > I know I can use surplus vacuum relays but at $35-40 a pop that ain't > gonna happen. > > Any and all suggestions will be appreciated. > > w3rv Brian Have you considered building your own coax relays? It is fairly easy to construct a SPST coax relay with glass enclosed tube shaped reed relays. Their performance may be acceptable to you, maybe not. But I have built my own coax relays from regular relays and have gotten adequate performance. Jerry Article: 217997 of rec.radio.amateur.antenna From: "Asimov" Subject: Vertical colinear Message-ID: References: <2YR%e.2887$nJ2.2349@fe73.usenetserver.com> Date: Sun, 02 Oct 2005 20:01:26 GMT "Dave VanHorn" bravely wrote to "All" (02 Oct 05 09:15:26) --- on the heady topic of "Vertical colinear" DV> From: "Dave VanHorn" DV> Xref: core-easynews rec.radio.amateur.antenna:217909 DV> I'm a bit confused over the construction of a vertical colinear. DV> The docs I've seen all are more or less the same, alternating DV> half-wave sections of coax or hardline. DV> The thing that's bending my head, is that there's a velocity factor DV> inside the coax, that presumably isn't there on the outside. DV> So, while a given section is a half wave on the outside, it's probably DV> more like 3/4 wave inside. DV> My understanding is that we are trying to get to a series of dipoles DV> all fed in phase, and yet this seems like it's not accomplishing that. DV> What am I missing? The wave energy travels alternately on the outside of the center conductor and then on the inside of the braid or shielding. So both see the same velocity factor. Does that make sense? A*s*i*m*o*v ... What if there were no hypothetical situations? Article: 217998 of rec.radio.amateur.antenna From: "Asimov" Subject: Re: Where to by random wire (longwire) antennas Message-ID: References: <1pivj1dpef92l4b61vlbqe03ravkj3dfbm@4ax.com> Date: Sun, 02 Oct 2005 20:01:28 GMT "Buther Boy" bravely wrote to "All" (02 Oct 05 06:59:32) --- on the heady topic of "Re: Where to by random wire (longwire) antennas" BB> From: Buther Boy BB> Xref: core-easynews rec.radio.amateur.antenna:217904 BB> Howard: BB> I somehow "dreamed" of being able to hide this random wire in my house BB> and tune it up, but that is looking more improbable by the minute. I BB> live in a town home and have no yard. Things don't look good, but I BB> have an excellent idea of how this all works. I appreciate your help, BB> Howard, and thanks for the detailed explanations. BB> Buther Boy You can hide wire in the oddest places. For example there is a 40 foot long clothesline outside in back of the house and it is made of steel. Someone a little bit crafty might replace that line with copperclad and nobody would be the wiser unless they looked a little closer. Hidden in plain sight! A*s*i*m*o*v ... "Please do not offer my god a peanut!" --Apu Article: 217999 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Need Suggestions for a Relay Source References: <1128269672.814425.42830@g14g2000cwa.googlegroups.com> Message-ID: Date: Sun, 02 Oct 2005 20:29:39 GMT Brian Kelly wrote: > I know I can use surplus vacuum relays but at $35-40 a pop that ain't > gonna happen. Hi Brian, the Omron LY series seem to handle 100w for me. Perhaps you can contact Omron about their limits. -- 73, Cecil http://www.qsl.net/w5dxp Article: 218000 of rec.radio.amateur.antenna From: "Dave VanHorn" References: <2YR%e.2887$nJ2.2349@fe73.usenetserver.com> Subject: Re: Vertical colinear Message-ID: Date: Sun, 2 Oct 2005 15:20:27 -0500 The wave energy travels alternately on the outside of the center conductor and then on the inside of the braid or shielding. So both see the same velocity factor. Does that make sense? Hmm.. So the first and second radiators are not in phase, but the first, third, fifth .... are in phase with each other, and the second, fourth, etc are in phase with each other? Article: 218001 of rec.radio.amateur.antenna From: "Fred W4JLE" References: <1jepj1p4qngh1ivp6bo4c1rc3vulugi6d5@4ax.com> <8bgpj11ofckhvd5dcg0umujbqav3508g9m@4ax.com> <0h0rj1ho78qtofjckgk0nrrqu4mgn8di5k@4ax.com> <2ym%e.16419$Xl2.3609@twister.nyroc.rr.com> <021sj1hb84shphia0dq78pl55r0q65sntl@4ax.com> <7d3a5$433e926c$97d558d8$32550@ALLTEL.NET> <8b50$433f1398$97d558d8$27686@ALLTEL.NET> <55b0c$433f44ba$97d558d8$25020@ALLTEL.NET> <2e4ae$43402795$97d558d8$23323@ALLTEL.NET> Subject: Re: "Hams to the Rescue After Katrina" MSNBC News Article Date: Sun, 2 Oct 2005 16:22:51 -0400 Message-ID: <3353f$434041cf$97d558d8$17905@ALLTEL.NET> OK, since your one of us we will give you a little slack. I will even point out that the example you found had nothing to do with rules, but sent an idiot to a non-existant forum who daily posted far out anti Bush stuff. "Pat Stevens" wrote in message news:LqW%e.18322$Xl2.4448@twister.nyroc.rr.com... > No, I only spent a couple of minutes looking. I thought it was interesting > that the shoe is now on the other foot, for you. Found your page > interesting, too. > However, I find it ironic that you call me a yankee. I have been trying to > shed the southerner image here with my friends and coworkers ever since I > moved up here from Myrtle Beach, after retiring from the Air Force. I grew > up in Beaufort, SC, near the Naval Hospital. Most people say that I still > have the accent. > > "Fred W4JLE" wrote in message > news:2e4ae$43402795$97d558d8$23323@ALLTEL.NET... > > Did we cause you to spend two days googling newsgroups? You could have > > found > > much better examples, I have been getting after net nazis since the ARPA > > days. Your still a damnyankee liberal twit. > > > > > > "Pat Stevens" wrote in message > > news:FTT%e.17504$Xl2.16932@twister.nyroc.rr.com... > >> Hey, Fred, > >> Does this ring a bell? Why do you feel this group would be any different > >> than the one you posted the following message to? > >> > >> Re: Man, Mr. bush Jr. sure is wicked evil eh? > >> by "w4jle" Apr 22, 2004 at 07:13 PM > >> > >> > >> Take this crap to alt.wewearaluminimum.hats > >> > >> Any body forwarding this much crap either is being paid to do it, or > >> seriously needs to get a life! > >> > >> > >> -- > >> W4jle.com - Home of the Professional Curmudgeon > >> > >> > >> > >> > >> "Fred W4JLE" wrote in message > >> news:55b0c$433f44ba$97d558d8$25020@ALLTEL.NET... > >> > Do I look like I am "hiding" you twit! > >> > > >> > I can see not only are you too stupid to use a newsreader, in addition > > you > >> > have no clue as to what can be gleaned from my call. > >> > > >> > I love upsetting supercillious net Nazis. Makes my day. > >> > > >> > "Pat Stevens" wrote in message > >> > news:R7H%e.17307$Xl2.9545@twister.nyroc.rr.com... > >> >> Ok. So, you were the bully who couldn't follow rules and believe that > >> > they > >> >> never apply to you. So, now you are continuing that ideology in life > > as > >> > you > >> >> "hide behind your keyboard." > >> > > >> > > >> > >> > > > > > > Article: 218002 of rec.radio.amateur.antenna From: "Dave VanHorn" References: <2YR%e.2887$nJ2.2349@fe73.usenetserver.com> Subject: Re: Vertical colinear Message-ID: Date: Sun, 2 Oct 2005 16:29:12 -0500 > I dont think you are missing anything. The feed points of each of the > radiating elements need to be in phase if 'broadside pattern max' is > desired. > > Do you intend to build an array, or just trying to understand them? Both. I have some FSJ1-50 that I got for the purpose. The docs that I've seen are all pretty consistent on how it should be put together, but I just don't understand the workings of it. IF the coax had a VF of 1.0, then it would make sense to me. Article: 218003 of rec.radio.amateur.antenna From: "Dave VanHorn" References: <2YR%e.2887$nJ2.2349@fe73.usenetserver.com> Subject: Re: Vertical colinear Message-ID: Date: Sun, 2 Oct 2005 16:30:03 -0500 Do all the elements radiate? Article: 218004 of rec.radio.amateur.antenna From: "Jerry Martes" References: <2YR%e.2887$nJ2.2349@fe73.usenetserver.com> Subject: Re: Vertical colinear Message-ID: <33Z%e.4169$097.2908@trnddc01> Date: Sun, 02 Oct 2005 22:20:47 GMT "Dave VanHorn" wrote in message news:JiY%e.2044$AR2.1519@fe81.usenetserver.com... > >> I dont think you are missing anything. The feed points of each of the >> radiating elements need to be in phase if 'broadside pattern max' is >> desired. >> >> Do you intend to build an array, or just trying to understand them? > > > Both. I have some FSJ1-50 that I got for the purpose. > > The docs that I've seen are all pretty consistent on how it should be put > together, but I just don't understand the workings of it. > > IF the coax had a VF of 1.0, then it would make sense to me. Dave Have you looked at the collinear antenna on the web written by "Brian Oblivious"? He cuts the coax into equal lengths 1/2 wave each. And that 1/2 wavelength accounts for the velocity of propagation inside the coax. So, each length is somewhat shorter than the free space halfwave It shows how he connected lengths of coax to make a collinear array. In my opinion, that would be a waste of that good coax you have. I once manufactured a vertical collinear antenna that had only one feed point and the other collinear elements were passively connected when stacked below the "fed dipole". Sometimes it is convenient to mount vertical half wave dipoles around a vertical supporting mast and have a "corporate feed harness" within the mast. That works well. Article: 218005 of rec.radio.amateur.antenna From: Ari Silversteinn Subject: Emergency Messaging And AM Date: Sun, 2 Oct 2005 18:29:13 -0400 Message-ID: Crossposted to: rec.radio.amateur.antenna,rec.radio.amateur.misc,rec,radio.amateur.equipment Novitiate here: I am learning AM broadcast basics in particular the issues regarding the geo-targeted broadcasting of alert messages from moving vehicles. Would most appreciate any assistance. Due to Katrina/Rita, the company I work for has been given the opportunity to demonstrate a messaging system that would reach out approximately 1 mile +/- in transmission deliverance. This would be an "overbroadcast" (my term) in that it would override local AM radio broadcasting to reach into cars, trucks etc. In particular, we are working with a stationary site (a chemical spill for instance) and an emergency vehicle that would move back and forth at and through the site, at up to 70 mph, broadcasting an alert, voice and tone message. Reading about LPAM, this looks technically possible but one concern I have is antennae size. A fire truck, for instance, could have an antenna mounted on its front, and up to 4 feet over the top of its roof, so we might look at as much as 20 feet of length. I realize this places us over the 3 meter max so one of the ???? is whether LFAM is realistic. Am I way off base here, can any antennae, fractal or other, or any AM antennae technology, be utilized to design an antenna and propagate this type of signal? All comments appreciated. -- Drop the alphabet for email Article: 218006 of rec.radio.amateur.antenna From: "Dave VanHorn" References: <2YR%e.2887$nJ2.2349@fe73.usenetserver.com> <33Z%e.4169$097.2908@trnddc01> Subject: Re: Vertical colinear Message-ID: Date: Sun, 2 Oct 2005 17:34:24 -0500 > Have you looked at the collinear antenna on the web written by "Brian > Oblivious"? No, I googled on it but didn't hit anything. > He cuts the coax into equal lengths 1/2 wave each. The articles I have seen are 1/2 wave * the velocity factor. Each one connecting center to shield. I can't picture how the elements all end up resonant, and in phase. Seems like one of those can't be true. > And that > 1/2 wavelength accounts for the velocity of propagation inside the coax. > So, each length is somewhat shorter than the free space halfwave It shows > how he connected lengths of coax to make a collinear array. In my opinion, > that would be a waste of that good coax you have. Why? It's nice rigid coax, and takes that sort of soldering well. Article: 218007 of rec.radio.amateur.antenna From: "Jerry Martes" References: <2YR%e.2887$nJ2.2349@fe73.usenetserver.com> <33Z%e.4169$097.2908@trnddc01> Subject: Re: Vertical colinear Message-ID: Date: Sun, 02 Oct 2005 22:51:01 GMT "Dave VanHorn" wrote in message news:QfZ%e.12769$qj2.6857@fe71.usenetserver.com... >> Have you looked at the collinear antenna on the web written by "Brian > >> Oblivious"? > > No, I googled on it but didn't hit anything. > >> He cuts the coax into equal lengths 1/2 wave each. > > The articles I have seen are 1/2 wave * the velocity factor. > > Each one connecting center to shield. > > I can't picture how the elements all end up resonant, and in phase. > > Seems like one of those can't be true. > >> And that > >> 1/2 wavelength accounts for the velocity of propagation inside the coax. > >> So, each length is somewhat shorter than the free space halfwave It shows > >> how he connected lengths of coax to make a collinear array. In my >> opinion, > >> that would be a waste of that good coax you have. > > Why? It's nice rigid coax, and takes that sort of soldering well. Dave I didnt mean to imply that your good coax wouldnt work well. I (perhaps wrongly) assumed that some garden variety coax might work OK for that staggering of lengths of coax, inner conductor to outer conductor. My web service thru Google, gets me that Brian Oblivious + Capt Kaboom site on their 802.11 2.4 GHz antenna. They indicate that the "elements" are 1/2 wave long minus the Vp inside the coax. That will put the feed points along that 'staggered' array, in phase. You have probably already considered that there will be some beam squint with this type of collinear. The "corporate fed" collinear will a maintain a main beam broadside, even though sidelobes do increase with bandwidth. Jerry Article: 218008 of rec.radio.amateur.antenna From: "Reg Edwards" Subject: Re: Small, non-resonant, horiz. loop. was Re: Magnetic Loop !!! Date: Sun, 2 Oct 2005 22:53:30 +0000 (UTC) Message-ID: References: <433D46F0.D0533E2B@shaw.ca> <433D7754.F019C9B2@shaw.ca> <11jrte940qbbf67@corp.supernews.com> <11jsujdpigc5dff@corp.supernews.com> <11jtdf05htl4j4a@corp.supernews.com> <11jub2qsovg9gae@corp.supernews.com> <11k05blgo2vgq65@corp.supernews.com> Dear Prof., I too am concerned about the abysmal and still falling standards of education in our schools and universities. Prof., I am very pleased to have met you. ---- Reg, G4FGQ Article: 218009 of rec.radio.amateur.antenna From: "Ken Taylor" References: Subject: Re: Emergency Messaging And AM Message-ID: Date: Mon, 3 Oct 2005 11:59:58 +1300 "Ari Silversteinn" wrote in message news:r7evtegkcjgt.kuwb55vmxpjg$.dlg@40tude.net... > Crossposted to: > > rec.radio.amateur.antenna,rec.radio.amateur.misc,rec,radio.amateur.equipment > > Novitiate here: > > I am learning AM broadcast basics in particular the issues regarding the > geo-targeted broadcasting of alert messages from moving vehicles. Would > most appreciate any assistance. > > Due to Katrina/Rita, the company I work for has been given the opportunity > to demonstrate a messaging system that would reach out approximately 1 > mile > +/- in transmission deliverance. This would be an "overbroadcast" (my > term) > in that it would override local AM radio broadcasting to reach into cars, > trucks etc. In particular, we are working with a stationary site (a > chemical spill for instance) and an emergency vehicle that would move back > and forth at and through the site, at up to 70 mph, broadcasting an alert, > voice and tone message. > > Reading about LPAM, this looks technically possible but one concern I have > is antennae size. A fire truck, for instance, could have an antenna > mounted > on its front, and up to 4 feet over the top of its roof, so we might look > at as much as 20 feet of length. I realize this places us over the 3 meter > max so one of the ???? is whether LFAM is realistic. > > Am I way off base here, can any antennae, fractal or other, or any AM > antennae technology, be utilized to design an antenna and propagate this > type of signal? > > All comments appreciated. > -- The things that pop into my mind are why AM rather than FM, which tends to be more local, and do you intend to 'over-broadcast' only the local channels (how many?) - I assume you intend to make the channel(s) selectable - or the entire band to ensure you get everyone? Assuming that there is a commercial AM broadcast station in the vicinity (what, 10 miles? 20 miles?) you are probably going to be flat out getting a mobile rig to ride over it. How do you intend to do this? Cheers. Ken Article: 218010 of rec.radio.amateur.antenna From: "Denton" Subject: using 450 ohm twin lead to feed 43 ft multiband groundmounted vertical Date: Sun, 2 Oct 2005 17:08:17 -0700 Message-ID: <11k0tjh6hr34l44@corp.supernews.com> I have been tinkering with a 43 ft ground mounted vertical with an extensive buried radial field. With a 4 to 1 voltage balun at the base, I have a good swr match particurlarly on 20 meters, and the antenna radiates and recieves comparabily with my 10 horizontal cage doublet fed with open wire ladderline. I recently replaced the coax that feeds the balun at the vertical's base with 450 ohm twin lead utilizing the same balun at the antennas feedpoint, and still get a decent signal report...again comparing to the big cage dipole. The twin lead is enclose within some left over grey plastic conduit if anything to keep it out of the weather and to keep it about 2 feet off of the ground, parallel to the ground.There is no evidence ot the plastic conduit detuning the twin lead. Tuning via either a link coupled transmatch or a dentron super tuner plus, utilizing its internal balun is broad smooth and no evidence of rfi in the shack with the exception of 30 meters. Wonder if anyone has tried this before and how did they like this feed arrangement. Thanks in advance, de Denton WB7TDG Article: 218011 of rec.radio.amateur.antenna From: Bob Bob Subject: Re: Emergency Messaging And AM References: Message-ID: <3lb613-l4c.ln1@p400bob.personal.cox.net> Date: Sun, 02 Oct 2005 19:46:56 -0500 Hi Ari I always wonder whether broadcast at the most common IF frequencies would be a viable alternative? (eg 455khz for AM) Legality issues aside of course... This would make frequency selection a little easier to engineer. You wouldnt have to divide your power budget into many operating frequencies as well. Problem is that you'd need a lot higher ERP especially since car mounted radios tend to be better shielded than portables. (You'll need to experiment some) Since part of your engineering exercise will be to determine what ERP you want from the system you are proposing, the size of the antenna only needs to be considered in line with the transmitter output power. Obviously there will be a useful compromise somewhere that is cost effective. You might for example want a 100 watt TX for each frequency with a fairly lossy/terminated and loaded antenna. Your first port of call will be to determine what the likely highest strength of an AM/FM broadcast signal you will need to override, add maybe 20dB to that and work out your needed ERP. You will find lots of texts about the inefficiencies of MF antennas mounted on motor vehicles so that will give you some numbers to work with. Remember that making the antenna wideband will also introduce substantial loss. Note that you cant design the system to always work as you'll have situations where the radio stations transmitting antenna is right next to then freeqy where the event occurred! Decide on some statistical coverage percentage thing etc etc... I worked for a concern in Sydney Australia that put in tunnel rebroadcast systems in the major underground roadworks in Sydney, Melbourne and Perth. Being in a tunnel of course there werent really any licensing issues. The system consisted of not only broadcast band (AM & FM) receivers but spot VHF/UHF FM receivers and transmitters for police, fire etc vehicles. Each broadcast frequency had its own transmitter. It was thought to be a better idea than using a wide band TX covering all frequencies. AM broadcast was coupled to a very long wire and the rest used a terminated leaky coax run. Cheers Bob W5/VK2YQA Ari Silversteinn wrote: > I am learning AM broadcast basics in particular the issues regarding the > geo-targeted broadcasting of alert messages from moving vehicles. Would > most appreciate any assistance. > Article: 218012 of rec.radio.amateur.antenna From: David Subject: Re: Help with Sleeve Dipole References: <11k04mh9vbli6d1@corp.supernews.com> Message-ID: Date: Mon, 03 Oct 2005 02:02:13 GMT I am still confused on this one. I see a 1/4 wave radiating element joined to another 1/4 wave radiating element that just happens to also act as a choke to reduce RF on the return braid of the RG174 coax. The point where they meet is supposed to look like the centre of a 1/2 wave dipole so the impedance must be around the 72 Ohms If the Sleeve is acting as a choke(Stub) then does it not need a second element as the return (ie is it not acting like a 1/4 length of coax where the tube is the outer braid and the RG174 cable running up the centre outer sheath is the dielectric and the outer braid of the RG174 becomes the inner conductor of the stub )? If this is correct then the electrical length of the sleeve must be modified by the presence of the RG174 coax outer sheath. The sleeve is sort of performing a dual function. As it is difficult to cut the tube once soldered in place, I will need to make heaps of these to get the length right. At least if I had a reasonable starting point it would minimize the number of iterations. The other issue is that I read about cutting lengths for elements and not that even an element in free space is trimmed down by about 3% to account for some "end effect" ? Would this also apply to my sleeve ? If so, then the length may be difficult to get right because if I make allowance for the end effect then the choking effect of the sleeve will not work as well. I do not want to reinvent the wheel here as these antennae are sold already being sold commercially and I am sure there are numerous people who have successfully made these. Therefore if I can learn from other people's mistakes and success, the starting point is much closer to the solution. I have a practical application but want to understand also. The requirement is that I have a small antenna that can be built into the end of a RF connector and plug directly onto a radio modem operating in the 915MHz band. The power is 1 Watt max. The design needs to be repeatable and not require trimming at every location (being portable I have no control over where the unit is located), as there is no decent ground plane, I need a unit that does not require radials or large ground plane. The low radiation angle and no requirement for large ground plane made the J-Pole look like a good contender but it was physically difficult to mount in this application. After looking around and opening up some commercial units, I noted many used the Choke Sleeve, 1/2 wave dipole antenna. This is why I am now wanting to understand how these work and have a good starting point for making them. The commercial units used molded construction that was difficult for me to emulate. I have started with RG174 Cable, 5/32 Brass tube all attached to SMA plug and used 1/4" nylon tubing as a radome. It goes together well and looks good but does not perform very well. Thanks for any further info. Dave VanHorn wrote: >>>With the tubing over a coaxial cable though it seems there is Vp related >>>to the dielectric formed between the sleeve and the outer sheath of the >>>coax cable but also the Metal has an Er value. > > > From what I understand, the RF will be traveling on the outside of the > sleeve, and won't "see" the internals at all. > So, the sleeve ends up as a 1/4 wavelength stub. > > Is the diameter of the tubing critical (will it impact adversely > >>>on SWR looking into this antenna). > > > It shouldn't be > > >>>The final point would be if I place some ferrite rings across the coax >>>below the sleeve, will this improve SWR ? > > > Not if the sleeve is doing it's job. > The sleeve's open end should look like a short at the operating frequency, > and keep RF off the feedline. > > > >>>Thanks >>> >>>Regards >>> >>>David >> >>David; >> >>That's why they call it the ART of antenna design. First you make the >>best mathematical calculations you can then you start cutting wire/tubing. >>Make your lengths slightly longer than the math says then prune the >>lengths until the antenna works the way you think it should. >> >>There are so many variables in antennas that this is the only practical >>way to make a new one. Once you find your optimal lengths you can make >>more to the same specs. However remember that just like in housing >>antenna's depend on three things: location, location, location and have to >>be custom adjusted for each site. >> >>Dave WD9BDZ > > > > Article: 218013 of rec.radio.amateur.antenna Date: Sun, 02 Oct 2005 21:28:05 -0500 From: Tom Ring Subject: Re: "Hams to the Rescue After Katrina" MSNBC News Article References: <1jepj1p4qngh1ivp6bo4c1rc3vulugi6d5@4ax.com> <8bgpj11ofckhvd5dcg0umujbqav3508g9m@4ax.com> <0h0rj1ho78qtofjckgk0nrrqu4mgn8di5k@4ax.com> <2ym%e.16419$Xl2.3609@twister.nyroc.rr.com> <021sj1hb84shphia0dq78pl55r0q65sntl@4ax.com> <7d3a5$433e926c$97d558d8$32550@ALLTEL.NET> <8b50$433f1398$97d558d8$27686@ALLTEL.NET> <55b0c$433f44ba$97d558d8$25020@ALLTEL.NET> <2e4ae$43402795$97d558d8$23323@ALLTEL.NET> Message-ID: <43409736$0$3760$39cecf19@news.twtelecom.net> Fred W4JLE wrote: > Did we cause you to spend two days googling newsgroups? You could have found > much better examples, I have been getting after net nazis since the ARPA > days. Your still a damnyankee liberal twit. Not everyone north of the moron line is a "llberal yankee twit", so shove it up your southern idiot ass. tom a northern nondemocrat K0TAR Article: 218014 of rec.radio.amateur.antenna From: David Subject: Re: Help with Sleeve Dipole References: <11k04mh9vbli6d1@corp.supernews.com> <1r51k1t8dsujf2k54gdhtivlc1h8gr3qjb@4ax.com> Message-ID: Date: Mon, 03 Oct 2005 03:14:52 GMT Richard, With regard to performance. Doing an A/B comparison between the commercial antenna and my version. The range achieved by the commercial antenna was approximately 4 times the range of my version. The range was determined by loss of using one end as a beacon and moving the test unit further away until it could no longer receive valid packets, then move in and out of range several times to confirm consistency. The same was done with my version. Before the test, I monitored the return port on the directional coupler on a Spectrum analyzer while seeping frequency from the sig. gen and noted the SWR on the commercial unit was lower than my version. (Though the measurement was not calibrated I could see the SWR was better but did not determine how much). Previously I designed a Microwave movement detector that operated at 1.2 GHz using Doppler principle. It used a microstrip tank circuit connected to a negative resistance oscillator. The design was published (RF Design magazine Dec 1986). Though there were many technical issues regarding the oscillator (how to adjust impedance in the base for optimal negative resistance looking into emitter, effect of moving the antenna, ground plane under the antenna etc etc), others were able to make the design just as per my prototype and it worked. They could then proceed to"play" with the design to change its performance. I really would have expected that a similar scenario would exist with antenna design (Someone has made one just like what I am wanting to make and is able to share with me the details on what they did that worked, then I would play with the design). I am grateful for the many responses I have received from my postings to this group and am confident there is much good information in what I have received but mixed with people's actual experience is a bunch of theoretical information that makes it hard to pick out what is useful. (ie. some of the information has conflicted and left me not understanding what is actually happening here). If someone has actually made these types of antennas and has some practical experience with them, that would be a fantastic starting point for me. (ie. Low power, UHF, portable). Richard Clark wrote: > On Mon, 03 Oct 2005 02:02:13 GMT, David wrote: > > >>If this is correct then the electrical length of the sleeve must be >>modified by the presence of the RG174 coax outer sheath. The sleeve is >>sort of performing a dual function. > > > Hi David, > > I think I pointed that out already. The effects of this jacket are > variable across many suggestions offered here over the years. > > >>As it is difficult to cut the tube once soldered in place, I will need >>to make heaps of these to get the length right. At least if I had a >>reasonable starting point it would minimize the number of iterations. > > > Ah yes, the pain of it all. I mentioned that too. You may as well > grit your teeth and set to it, there is no shortcut to this all. > > >>The other issue is that I read about cutting lengths for elements and >>not that even an element in free space is trimmed down by about 3% to >>account for some "end effect" ? Would this also apply to my sleeve ? If >>so, then the length may be difficult to get right because if I make >>allowance for the end effect then the choking effect of the sleeve will >>not work as well. > > > You might want to work this backwards. That is start off with a > successful choke section of the sleeve. Let that dictate what follows > because its isolation will mediate what I describe. If you have any > experience with what is called an Offset Center Fed Dipole, you would > find that it offers a closer match to 50 Ohms. You are using the > dipole as a variable match by finding the 50 Ohm portion along its > full length. This means that the portion above the sleeve's > attachment to the drive point may not be the classic length (and > certainly not accounted by the 3% of the "end effect" - not even > close). > > That is neither here nor there because at that point you will have > simultaneously achieved resonance, a match, and isolation; and yet by > no fixed formula pulled out of a hat, nor accredited by an institution > of higher learning. > > And, by the way, it isn't going to pull together in the first pass. I > hope you have a stack of tubing, so put on a happy face and get down > to it. > > >>This is why I am now wanting to understand how these work and have a >>good starting point for making them. The commercia