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#1
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Underground antenna
Hello,
googling about "underground antenna", i found this article: http://www.caves.org/section/commelect/nec-4/nec-4.html that talk about a version of NEC capable to modeling under-the-ground wires. IIRC also Roy W7EL write down months ago something about this, and about the why the NEC capable of this kind of modeling (buried wires and so on) is not released to the general public. Roy, if you gently can re-explain to me this i'll be grateful. Just for my personal information, wondering if someone played with buried or submersed antennas and (especially from 40 meters going lower in frequency) get some interesting result. Thanks for reading and for replies, and as usual sry for my poor english. -.-. --.- , Italy. |
#2
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Underground antenna
-.-. --.- wrote:
Hello, googling about "underground antenna", i found this article: http://www.caves.org/section/commelect/nec-4/nec-4.html that talk about a version of NEC capable to modeling under-the-ground wires. IIRC also Roy W7EL write down months ago something about this, and about the why the NEC capable of this kind of modeling (buried wires and so on) is not released to the general public. Roy, if you gently can re-explain to me this i'll be grateful. Just for my personal information, wondering if someone played with buried or submersed antennas and (especially from 40 meters going lower in frequency) get some interesting result. Thanks for reading and for replies, and as usual sry for my poor english. -.-. --.- , Italy. NEC-4 is capable of modeling buried wires, and NEC-4 is available to the public. For information about purchasing NEC-4 see https://ipo.llnl.gov/?q=technologies...ware-app&s=NEC. Roy Lewallen, W7EL |
#3
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Underground antenna
On Aug 13, 3:09*am, "-.-. --.-" wrote:
Hello, googling about "underground antenna", i found this article:http://www.caves.org/section/commelect/nec-4/nec-4.html that talk about a version of NEC capable to modeling under-the-ground wires. IIRC also Roy W7EL write down months ago something about this, and about the why the NEC capable of this kind of modeling (buried wires and so on) is not released to the general public. Roy, if you gently can re-explain to me this i'll be grateful. Just for my personal information, wondering if someone played with buried or submersed antennas and (especially from 40 meters going lower in frequency) get some interesting result. Thanks for reading and for replies, and as usual sry for my poor english. -.-. --.- , Italy. Hi there, I noticed at one point a reference to displacement current where ..... " in this case it cannot be ignored!" Where and why in modeling would one ignore displacement current when it is part and parcel of Maxwell's laws? Many thanks |
#4
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Underground antenna
Roy Lewallen wrote:
-.-. --.- wrote: Hello, -.-. --.- , Italy. NEC-4 is capable of modeling buried wires, and NEC-4 is available to the public. For information about purchasing NEC-4 see https://ipo.llnl.gov/?q=technologies...ware-app&s=NEC. Roy Lewallen, W7EL I like the whole part of the form where I had to certify that I wasn't doing nuclear weapons design, nor was I planning on using NEC4 for the design, development, production, stockpiling, or use of chemical or biological weapons. They apparently don't care if I do those things, I just might not be able to use NEC4 in the process. |
#5
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Underground antenna
Jim Lux wrote:
I like the whole part of the form where I had to certify that I wasn't doing nuclear weapons design, nor was I planning on using NEC4 for the design, development, production, stockpiling, or use of chemical or biological weapons. They apparently don't care if I do those things, I just might not be able to use NEC4 in the process. The only important thing is that you *say* you're not doing those things. We all know that nuclear, chemical and biological weapons developers would never lie about what they're doing. But this is a big step beyond how things used to be. Until a few years ago, NEC-4 could be sold only to people who said they were U.S. citizens for use in the U.S. So it was trivial for any potential enemy to get the program which could be carried anywhere in the world on a floppy disk in a shirt pocket, or even sent by email. In the meantime, users in friendly countries had to apply for an exemption via diplomatic channels. I know of at least one case where this was done, and approval took several years. Roy Lewallen, W7EL |
#6
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Underground antenna
Just for my personal information, wondering if someone played with buried
or submersed antennas and (especially from 40 meters going lower in frequency) get some interesting result. I once read an article in which it was stated that in a simple vertical, the element current it restricted by the ground current, and any attempt to increase the ground curent resulted in an increase in efficiency. The article went on to state that an antenna having maximum contact with the ground would be the most efficient, and in test a 1/2-wave dipole burried underground could have an efficiency approaching 98% that of a dummy load. The advantages are numerouse, such as the lack of an antenna support structure, but for VHF arrays there could be a huge problem with direction since the torque required to turn only a 2m 8-ele Yagi would be over a ton. |
#7
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Underground antenna
"Dennis Whatley" schreef in
bericht ... The advantages are numerouse, such as the lack of an antenna support structure, but for VHF arrays there could be a huge problem with direction since the torque required to turn only a 2m 8-ele Yagi would be over a ton. That's why farmers used horses and nowadays tractors to pull the array through the ground. But you know farmers: they always forget to connect the feedline! That's why you never hear them on the air. 73 - Gerard - PE1OUD E-mail: |
#8
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Underground antenna
The advantages are numerouse, such as the lack of an antenna support
structure, but for VHF arrays there could be a huge problem with direction since the torque required to turn only a 2m 8-ele Yagi would be over a ton. That's why farmers used horses and nowadays tractors to pull the array through the ground. But you know farmers: they always forget to connect the feedline! That's why you never hear them on the air. Hi Gerard, and there I was, thinking it was because an underground transmitting station needed an underground receiver station. Thanks a million, now I know why there are so few farmers on CB. |
#9
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Underground antenna
On Mon, 17 Aug 2009 18:48:43 GMT, Dennis Whatley wrote:
Just for my personal information, wondering if someone played with buried or submersed antennas and (especially from 40 meters going lower in frequency) get some interesting result. I once read an article in which it was stated that in a simple vertical, the element current it restricted by the ground current, and any attempt to increase the ground curent resulted in an increase in efficiency. The article went on to state that an antenna having maximum contact with the ground would be the most efficient, and in test a 1/2-wave dipole burried underground could have an efficiency approaching 98% that of a dummy load. The advantages are numerouse, such as the lack of an antenna support structure, but for VHF arrays there could be a huge problem with direction since the torque required to turn only a 2m 8-ele Yagi would be over a ton. I read that article, too. 'Twas in an April QST back some years ago. Jonesy -- Marvin L Jones | jonz | W3DHJ | linux 38.24N 104.55W | @ config.com | Jonesy | OS/2 * Killfiling google & XXXXbanter.com: jonz.net/ng.htm |
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