Re: [Elecraft] Underground Antennas (WAS: Ham Ingenuity)
The only ground antenna I worked with was a 270 ft. horizontal loop made from #28 enemeled wire. It was in a pentagon shape and laying right on the ground. It loaded well with my antenna coupler thru a 1:1 homemade balun wound on a big 4 ferrite toroid form with about 12 turns trifilar wound #18 solid hookup wire. I worked quite well I thought, except the signals incoming and outgoing were down about 20 db. Even did a few QSO's on 40 and 20 meters with it QRP with the K1. NOT the most effective antenna by any means, but surely a good 'stealth' antenna for people in stuffy subdivisions with those stupid covenants! If I were going to make it a permanent installation I'd use some single conductor #14 solid insulated wire from Home Depot for protection against breakage. Any Nosy Neighborhood Association idiot snoop could be told it was a wire to keep dogs off your lawn, or to keep you dog in your yard with a special collar. Such an antenna would be a whole lot better than a short loaded whip or some other less desirable rigup. 73, Sandy W5TVW - Original Message - From: Stuart Rohre [EMAIL PROTECTED] To: Ron D'Eau Claire [EMAIL PROTECTED]; elecraft elecraft@mailman.qth.net Sent: Thursday, March 23, 2006 11:31 PM Subject: Re: [Elecraft] Underground Antennas (WAS: Ham Ingenuity) | Hee, hee. Bet you did not expect someone to report they had experience with | underwater antennas, but I have been on an experimental project to put the | Rogers FLEX Folded Conical Helical HF antenna on a submerged vessel. | (Written up in IEEE Transactions on Antennas and Propagation) | | Of course, it was not used while submerged. | | I also had some HF antennas on ocean buoys that wash over pretty regularly | in a high sea, so it is operated underwater part of the time. Signal drops | as you would expect. At 5 watts power, they were not going to work well | when in washover. SWR goes crazy, but they right themselves pretty quick | and that is what foldback SWR protection is for. Rig was FT 5 watter. | | -Stuart | K5KVH | | | | ___ | Elecraft mailing list | Post to: Elecraft@mailman.qth.net | You must be a subscriber to post to the list. | Subscriber Info (Addr. Change, sub, unsub etc.): | http://mailman.qth.net/mailman/listinfo/elecraft | | Help: http://mailman.qth.net/subscribers.htm | Elecraft web page: http://www.elecraft.com | | | | -- | No virus found in this incoming message. | Checked by AVG Free Edition. | Version: 7.1.385 / Virus Database: 268.3.0/290 - Release Date: 3/23/2006 | | ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
RE: [Elecraft] Underground Antennas (WAS: Ham Ingenuity)
Anybody have any idea how an 80m loop would work at 3m height? We just moved into a new place with NO ANTENNA RESTRICTIONS, but I fell down hard last summer (3 weeks unconscious in ICU) and am not tempted to get very high again. All this talk about on-ground and under-ground antennas made me think of hanging a W0MHS Loop-Skywire at a low height. That a LOT of copperweld for something that hasn’t a chance. I’d hire someone to hang a doublet if I thought it would be much better. But the whole neighborhood is in a hole, about 75 feet below the prevailing terrain, so even a 50’ doublet is really 25’ undergroundg. The hole is several wavelengths wide, so from my roof, the tops of the trees on the “rim” are up about 25 degrees, so very low DX takeoff just ain’t gonna happen. Maybe it’s time I learned if I can run one of those Antenna Modelers. Should I look for Windoze or Linux flavors? Dan / WG4S / K2 #2456 snip The only ground antenna I worked with was a 270 ft. horizontal loop made from #28 enemeled wire. It was in a pentagon shape and laying right on the ground. /snip ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
Re: [Elecraft] Underground Antennas (WAS: Ham Ingenuity)
Dan Barker wrote: Anybody have any idea how an 80m loop would work at 3m height? It would probably work adequately as an NVIS (near vertical incidence something-or-other) antenna. In other words, you would have *very* strong signals out to a couple of hundred miles on 40 meters, a little less on 80. It will not work well for longer paths, although I'm sure there will be surprises. However, I would prefer a doublet if the loop has to go around houses, etc. The reason is that a loop will magnetically couple to house wiring, etc., making it much more prone to RFI and to noise pickup. A simple doublet at this height, fed with ladder line and tuned by a good balanced tuner will probably work as well or better than the loop with fewer problems. You won't work a lot of DX with it, but you will have good local coverage. -- 73, Vic, K2VCO Fresno CA http://www.qsl.net/k2vco ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
RE: [Elecraft] Underground Antennas (WAS: Ham Ingenuity)
--- Dan Barker [EMAIL PROTECTED] wrote: not tempted to get very high again. There's a dope smokin' joke in there just screamin' to get out! Sorry to hear about your fall...sounds like it was a nasty one. If it had to happen, I hope it was at least in pursuit of a better antenna system! 73, Ken Alexander VE3HLS ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
[Elecraft] Underground Antennas (WAS: Ham Ingenuity)
Phil, K2ASP asked: I guess that with enough power one can put any antenna underground (GWEN) or even underwater (SUBCOMM) but let's not give my wife any more ammunition!! Has anyone here tried it? -- Oh, yes. Work with subterranean antennas dates back to 1923, at least, in the Amateur literature. They have also been the subject of various April's fools spoofs that some Hams get the idea that they don't work at all, but apparently they do with the limitations I described. It seems that losses go up in direct proportion to the coupling of the antenna with the earth, so the losses increase as the antenna approaches the earth and increase with depth in the earth. In the 1960's (I think it was, I'm away from my Ham library at the moment) more experimentation was done on the current HF Ham bands by a US Amateur with measurements of about 16 dB loss compared to an elevated antenna that are reported in Hey's book, Practical Wire Antennas. Restricted use of Urban space is not limited to the USA, apparently. A Russian Ham, Igor Grigorov, RK3ZK, has written a book that also touches on near-earth and underground antennas. His book, Urban Antennas is reviewed by Cebik at: http://www.antennex.com/shack/Nov01/urbanrvw.html In that review Cebik writes: Underground antennas, long familiar to those people who had to operate clandestine radios within occupied regions during World War II, are attracting professional investigation in the US these days. Whether in a near-surface location or erected deep within a cave, underground antennas do work for both short and long distance communications. No, they will not compete with the long Yagis on towers reaching the 200' level during a CQ or ARRL DX contest, but that is not their purpose. They can permit communication of essential information over various types of propagation paths. Interestingly, it is difficult to get a bearing on these antennas from any significant distance, thus adding to their security. I may have to add that book to my library G. Ron AC7AC ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
Re: [Elecraft] Underground Antennas (WAS: Ham Ingenuity)
Hee, hee. Bet you did not expect someone to report they had experience with underwater antennas, but I have been on an experimental project to put the Rogers FLEX Folded Conical Helical HF antenna on a submerged vessel. (Written up in IEEE Transactions on Antennas and Propagation) Of course, it was not used while submerged. I also had some HF antennas on ocean buoys that wash over pretty regularly in a high sea, so it is operated underwater part of the time. Signal drops as you would expect. At 5 watts power, they were not going to work well when in washover. SWR goes crazy, but they right themselves pretty quick and that is what foldback SWR protection is for. Rig was FT 5 watter. -Stuart K5KVH ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
