Horizontal Loop Antenna
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I've been thinking about what kind of antenna to put up. With my height and
deed restrictions, I'm quite limited. I've thought about putting up a horizontal loop antenna. Basically I was planning to run some enameled magnet wire around the perimeter of the roof (I have no plans on running more than 10 watts). The wire would lay under the shingles so it can't be seen. The antenna will be 1 WL long on 80 meters. I'll run coax down to the K2 + ATU. This is similar to "The Loop Skywire" described in the November 1985 issue of QST. Anyone have experience (or see a problem) with this antenna? Thanks, Kevin N8IQ _______________________________________________ Elecraft mailing list Post to: [hidden email] 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 |
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Kevin Shaw wrote:
> I've thought about putting up a > horizontal loop antenna. Basically I was planning to run some enameled > magnet wire around the perimeter of the roof (I have no plans on running > more than 10 watts). The wire would lay under the shingles so it can't be > seen. The antenna will be 1 WL long on 80 meters. I'll run coax down to the > K2 + ATU. I ran a square loop with 65' sides, up 20 feet, fed at a corner, through EZNEC. The antenna would be a good NVIS antenna on 80 and 40 meters, with maximum radiation straight up on 80 and at 55 degrees on 40. It would be good for QSOs up to a couple of hundred miles, but poor for longer distances. Horizontal patterns would be round on 80 and sort of a slightly squashed circle on 40. On 20, you would get maximum radiation at 40 degrees, a little better, and the horizontal pattern would be a squashed cloverleaf. Feeding it in the center of a side gives you about the same on 80 and 40, and makes the 20 meter pattern look like 80! Also, an antenna in this location would couple very strongly to conductors inside the house. A lot of power would be wasted, RFI potential maximized, and it would pick up a LOT of noise. My conclusion is: don't do it. -- 73, Vic, K2VCO Fresno CA http://www.qsl.net/k2vco _______________________________________________ Elecraft mailing list Post to: [hidden email] 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 |
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> -----Original Message-----
> I ran a square loop with 65' sides, up 20 feet, fed at a > corner, through EZNEC. The antenna would be a good NVIS > antenna on 80 and 40 meters, with maximum radiation straight > up on 80 and at 55 degrees on 40. It would be good for QSOs > up to a couple of hundred miles, but poor for longer > distances. I have had such an antenna for almost 5 years. About 75 meters long and at a height varying between 5 and 10 meters. It is fixed in five positions, two on my house, and three in trees in my garden. Based on the www.cebik.com simulations, my expectation was also as a local antenna on 80 meters, but it has turned out different: Now I have had QSOs with 65 countries on 80 meters, most of them using QRP CW and with all continents including Australia (... 100 W CW, not QRP!). Probably I have been lucky with special propagation that has helped me, Pedersen rays or what have you. It could also be that I have a stream through my garden which makes the soil especially favorable or some other reason, but anyway I am very happy with the antenna. The concerns regarding mounting on the house, RFI and coupling etc are of course independent of this and will reduce performance. 73 Sverre LA3ZA http://www.qslnet.de/la3za/ _______________________________________________ Elecraft mailing list Post to: [hidden email] 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 |
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In reply to this post by Kevin Shaw
The W0MHS Loop Skywire is a great antenna, but feed it with some ladder
line. You don't say how high it will be, but I ran mine around the house at about 40 feet. Three corners tied to trees, one corner on a pulley/weight setup. Worked Japan (from Eastern Seaboard) on 750 mW. Mine was 14g Copperweld, and nearly invisible. Dan / WG4S -----Original Message----- From: [hidden email] [mailto:[hidden email]]On Behalf Of Kevin Shaw Sent: Wednesday, December 21, 2005 2:58 PM To: [hidden email] Subject: [Elecraft] Horizontal Loop Antenna I've been thinking about what kind of antenna to put up. With my height and deed restrictions, I'm quite limited. I've thought about putting up a horizontal loop antenna. Basically I was planning to run some enameled magnet wire around the perimeter of the roof (I have no plans on running more than 10 watts). The wire would lay under the shingles so it can't be seen. The antenna will be 1 WL long on 80 meters. I'll run coax down to the K2 + ATU. This is similar to "The Loop Skywire" described in the November 1985 issue of QST. Anyone have experience (or see a problem) with this antenna? Thanks, Kevin N8IQ _______________________________________________ Elecraft mailing list Post to: [hidden email] 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 mailing list Post to: [hidden email] 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 |
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> -----Original Message-----
> The W0MHS Loop Skywire is a great antenna, but feed it with > some ladder line. > I should add that this is exactly how I feed mine. About 8 meters of ladder line (450 ohms I believe), into an Elecraft 4:1 balun and then to the KAT2/KAT100. The ladder line is essential to reduce losses due to varying SWR. 73 Sverre LA3ZA http://www.qslnet.de/la3za/ _______________________________________________ Elecraft mailing list Post to: [hidden email] 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 |
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In reply to this post by Vic K2VCO
Whether you will get good results with your loop under the shingles depends
on the amount of metal flashing on the edges of your roof. Also, on the amount of metal enclosed by it in your attic. we tried one on a Red Cross building that had perimeter flashing and even on standoff insulators, the loop was a poor performer. The insulators were 5 inches away from the flashing. Perhaps the flashing was the shorted turn syndrome. A dipole NVIS antenna has worked much better above this particular commercial flat roof. Under the roof were red iron bar joists, which also are grounded. Stuart K5KVH _______________________________________________ Elecraft mailing list Post to: [hidden email] 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: Horizontal Loop Antenna
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In reply to this post by Kevin Shaw
Kevin,
You may do better with wire through the shrubs than around the house, if you can hide it. I know many folks have god luck with supported thin enamel wire when they have to, but you might try something like The Wireman #532, which is 18 gauge and black insulated. It will pull well through trees and shrubs and is hard to see. I used 400' of it for my loop. I recently put up a low 400' loop around the perimeter of two city lots (renting next door during a remodel) and I can hear signals on 160m where there were almost none before, and can easily work out to about 300 miles. My G5RV is also deaf on 15m but with the loop I worked Novia Scotia from Northern California on 2.5W. So the loop works great on 160, where it is about 2/3 lambda, and great on 15m where it is about 10 wavelengths. It is quieter than the doublet on all bands, though signals are a little lower on 20m, and it won't load up on 12m. With your shorter loop, I would expect you may find different results, but as long as you observe basic RF and AC line safety, experimenting with wire antennas is fun and cheap. And f you don't like the lobes, move the feedpoint. As for feeding the loop, I would suggest window line to an outdoor balun such as the BL1 or the new BL2 with its switchable transformer, then to a bulkhead through the wall. For non-resonant use coax is likely to have more losses, but it doesn't cost you much to try both. I posted a longer (!) message to HFPack Yahoo Group, detailing performance by band and giving info about the mechanical construction and raising techniques. 73, Leigh / WA5ZNU On Wed, 21 Dec 2005 11:59 am, Kevin Shaw wrote: > I've been thinking about what kind of antenna to put up. With my height > and > deed restrictions, I'm quite limited. I've thought about putting up a > horizontal loop antenna. Basically I was planning to run some enameled > magnet wire around the perimeter of the roof (I have no plans on > running > more than 10 watts). The wire would lay under the shingles so it can't > be > seen. The antenna will be 1 WL long on 80 meters. I'll run coax down to > the > K2 + ATU. > > > > This is similar to "The Loop Skywire" described in the November 1985 > issue > of QST. Anyone have experience (or see a problem) with this antenna? > > Thanks,> > Kevin > > N8IQ Elecraft mailing list Post to: [hidden email] 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 |
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In reply to this post by Kevin Shaw
At 11:58 AM 2005-12-21, Kevin, N8IQ wrote:
>I've been thinking about what kind of antenna to put up. With my height and >deed restrictions, I'm quite limited. I've thought about putting up a >horizontal loop antenna. Basically I was planning to run some enameled >magnet wire around the perimeter of the roof (I have no plans on running >more than 10 watts). The wire would lay under the shingles so it can't be >seen. The antenna will be 1 WL long on 80 meters. I'll run coax down to the >K2 + ATU. > >This is similar to "The Loop Skywire" described in the November 1985 issue >of QST. Anyone have experience (or see a problem) with this antenna? Kevin, Just be sure that the high voltage points on the antenna are well insulated from your shingles. The voltages are maximum at 1/4 wavelength away from point on the loop which is opposite the feedpoint (and every 1/2 wl from those points on 40m and higher bands). Even with 10 watts, you could see about 200 volts (rms) RF present. When the shingles are damp, you may see a bit of detuning from increased capacitive loading (and a little extra loss). I used a 30 foot high horizontal loop (1 wl on 80m) at my Seattle QTH and was quite pleased with its performance on 80m-10m. One side ran closely parallel to the aluminum gutter above the second story. The remainder of the loop was stretched to trees across a small creek. Feed was through a short length of 300 ohm line and a link-coupled balanced tuner. The loop was originally made from stealth #26 magnet wire, which was fine for RF (100 watts), but was often trashed by falling tree branches. It was later upgraded to bare #22 and the mechanical problems were nearly nonexistent (and it was still nearly invisible). When I started to get ice buildup, I connected the loop to a low voltage DC supply which warmed the wire enough to melt the ice off. ARL 61, Terry N6RY _______________________________________________ Elecraft mailing list Post to: [hidden email] 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 |
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In reply to this post by Stuart Rohre
Thanks to everyone who responded about my proposed horizontal loop antenna.
I was outside today and had an idea for an antenna installation. I primarily want to work (or try to work) some DX. This, of course, requires a low elevation angle. A vertical would probably be a better solution due to my height restrictions. I live on a conservation lot with 6-8 acres of woods behind the house. I own maybe 15 feet into the woods. Being Florida, this is wetlands. There is almost always standing water or VERY moist soil (mud) in the woods. I would think that this would present an excellent ground for a vertical antenna to work against. My idea is to get a vertical antenna, paint it dark brown, and place it in the woods. I'd place it deep in the brush next to a tree. Nobody (except a deer or bobcat, etc...) would be able to touch it. Kevin N8IQ/4 _______________________________________________ Elecraft mailing list Post to: [hidden email] 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 |
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