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#421
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#422
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Mark Keith wrote:
"I`ve seen nothing so far to indicate we are designing in gross error or even noticible error." Neither have I. But, I`ve read several stimulating perceptions which were new to me and motivated me to investigate and improve my understanding. I am sorry My statement, "Close the patent office!" offended Mark. I have no doubt that Mark has optimized his mobil antennas. Forty years after Faraday suggested the existence of electric fields in about 1842, Heinrich Hertz built a spark transmitter and receiver. The receiver was just a loop with a gap which sparked when Hertz keyed his transmitter. It was resonant at 53 MHz or near the frequencies now assigned as TV Channel 2 in the USA. Hertz optimized his antennas for maximum transmission distance and achieved about 30 feet. In the last 160 years there have been many interesting antenna developments and more are yet to come. Most are not likely predictable. Best regards, Richard Harrison, KB5WZI |
#424
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On 15 Nov 2003 11:00:19 -0800, (Art Unwin KB9MZ)
wrote: |Can you tell me where I can find what the orientation of coil cross |section does for efficiency ? Michaels ("Loading Coils for 160-Meter Antennas", QST, April 1990, pp 28-31) might help. |There are circular cross sections, edge wound cross sections and also |the ribbon type that Collins uses where the ribbon is coiled on a |adjacent coil former, why did they choose this method? I believe the Collins ribbon inductors were designed for variability, i.e., tunable without any sliding contacts as in roller inductors. |I am pursuing efficiency, reduction of losses and Collins have a great |reputation so which form is the state of the art especially with |corner flux density. |Another question is that if we split up an inductance into two parts |does the form factor include the summation of inductances or does the |distance inbetween |where coil linkage is not fully formed affect efficiency for the |worse. |Discussion like this thread hopefully will enlarge our education to |see if such things matter . Another question I struggle with is to put |another element inside the coil where there is max flux density but |again it can't be resolved by modeling. With the multi antenna experts |onboard it is always a possibility that a modicom of information will |be provided that will benefit all. |As far as inductances, all is not known to my mind and I always would |like to be privy to more information, and not because I want to build |a whip Another interesting reference is Rhea ("Filters and an Oscillator Using a New Solenoid Model", Applied Microwave & Wireless, November 2000, pp 30-42) In a nutshell, his premise is that the classic inductor model is in error, particularly with respect interwinding capacitance. Some other articles that should be read by all participating in this thread are by Cebik. http://www.cebik.com/amod/amod13.html http://www.cebik.com/amod/amod14.html |
#425
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Wes Stewart wrote in message . ..
On 15 Nov 2003 11:00:19 -0800, (Art Unwin KB9MZ) wrote: |Can you tell me where I can find what the orientation of coil cross |section does for efficiency ? Michaels ("Loading Coils for 160-Meter Antennas", QST, April 1990, pp 28-31) might help. |There are circular cross sections, edge wound cross sections and also |the ribbon type that Collins uses where the ribbon is coiled on a |adjacent coil former, why did they choose this method? I believe the Collins ribbon inductors were designed for variability, i.e., tunable without any sliding contacts as in roller inductors. |I am pursuing efficiency, reduction of losses and Collins have a great |reputation so which form is the state of the art especially with |corner flux density. |Another question is that if we split up an inductance into two parts |does the form factor include the summation of inductances or does the |distance inbetween |where coil linkage is not fully formed affect efficiency for the |worse. |Discussion like this thread hopefully will enlarge our education to |see if such things matter . Another question I struggle with is to put |another element inside the coil where there is max flux density but |again it can't be resolved by modeling. With the multi antenna experts |onboard it is always a possibility that a modicom of information will |be provided that will benefit all. |As far as inductances, all is not known to my mind and I always would |like to be privy to more information, and not because I want to build |a whip Another interesting reference is Rhea ("Filters and an Oscillator Using a New Solenoid Model", Applied Microwave & Wireless, November 2000, pp 30-42) In a nutshell, his premise is that the classic inductor model is in error, particularly with respect interwinding capacitance. Some other articles that should be read by all participating in this thread are by Cebik. http://www.cebik.com/amod/amod13.html http://www.cebik.com/amod/amod14.html Thank you for those references Wes. I really didn't expect to hear from you again. I now have the computor program to simulate my actual antenna so efficiency is now of major importance ,I can up my efficiency to 50 per cent by hanging a wire down from the dipole ends which I am not comfortable about and would rather aproach the coil for loss reduction and go for a beam setup by using the radiation efficiently by making it fully directional stead of figure 8 form and hopefully I can get those extracts Reg I tried to enter your page once but I am so computor incompetant. Looked at a tank circuit today and it was wound flat ribbon form! Looking forward to looking at this fresh info Many thanks to both of you Art |
#426
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Art, KB9MZ wrote:
"I can up my efficiency to 50 per cent by hanging a wire down from the dipole ends which I am not comfortable about---." Why would Art be uncomfortable about improving efficiency by hanging a wire down? Maybe he does not believe his model is correct. Maybe he doesn`t want some directivity change that comes with hanging a wire down. Maybe there is some physical problem with hanging a wire down. The problem with a loading coil is increased loss. Capacitance is usually low loss. As Yuri, K3BU has noted, there is much to be learned from reading ON4UN`s Chapter 9 about antenna loading even though everything regarding vertical antennas doesn`t translate readily to horizontal antennas. ON4UN includes horizontally polarized antennas in "Low-Band DXing". It`s easy to read, well illustrated, and full of good references. It helps if you want to design your own antenna because it tells why as well as how. Best regards, Richard Harrison, KB5WZI |
#427
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Reg I tried to enter your page once but I am so computor incompetant.
---------------------------------------- Art, I'm afraid there's not much hope for you then. Why not try keeping tropical fish ? It's very relaxing although it can be livened up by introducing just one pirana to the tank. ;o) ---- Yours, Reg |
#428
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David J. Windisch wrote:
Speaking of pirhanas in the tank, this humble lurker and scribe takes this opportunity to thank and congratulate you pirhanas posting here for driving the likes of ... et al., right off this reflector with your feeding frenzies over triviae, minutiae, and inconsequential stuff. A larger question might be: Why do some (not all) of those guys stake their reputations and egos on that very "triviae, minutiae, and inconsequential stuff"? Some of those guys on your list disagree loud and long with each other, both sides determined never to admit a mistake of any kind. Many list their degrees and accomplishments as if those things are a vaccination against mistakes. Driving a person off a public unmoderated newsgroup is impossible. What causes people to leave this newsgroup under pressure is pride plus the heat in the kitchen. Do you think we really need a newsgroup guru upper class whose assertions are immune from other questioning minds? -- 73, Cecil http://www.qsl.net/w5dxp -----= Posted via Newsfeeds.Com, Uncensored Usenet News =----- http://www.newsfeeds.com - The #1 Newsgroup Service in the World! -----== Over 100,000 Newsgroups - 19 Different Servers! =----- |
#429
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On Mon, 17 Nov 2003 05:56:29 -0500, "David J. Windisch"
wrote: |Speaking of pirhanas in the tank, this humble lurker and scribe takes this |opportunity to thank and congratulate you pirhanas posting here for driving |the likes of Gary Coffman, Tom Rauch, Tom Bruhns, Bart Rowlett, Steve Best, |Bob Haviland, Roy Lewallen, Wes Stewart, Ian White, Walt Maxwell, Joe |Reisert .... et al., right off this reflector with your feeding frenzies |over triviae, minutiae, and inconsequential stuff. While I'm honored to be counted among the others you speak of Dave, I think you're not lurking often enough g. I must say that some of us on the list are still here. I don't know the reasons why some of the others are not regulars anymore; it could be what you cite or it could just be the press of other things in life. I too miss their contributions. Nevertheless, it's just usenet and not something to be taken very seriously or to get upset about. The thin skinned should not apply g. Actually, I think some of the participants in the latest thread might be off dreaming up some experiments or new models to bring back to the discussion. Notwithstanding the bullheadedness and wacky thinking of some of the usual suspects, there has been some thought provoking discussion. Regards, Wes N7WS |
#430
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