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Nice jd!
Many folks here are missing the point. It doesn't have to be 2X wavelength or even 1X wavelength. Just string up a horiz. loop anywhere you can and as long as you can make it. Don't worry about height above ground or if it is in a circular, square or trapezoid, or what have you, configuration. If it is anywhere near as high as your proposed longwire or dipole it will work just as well but over a much broader swath of frequencies. Think of its performance as much like a discone antenna at VHF & UHF - no gain over a half-wave vertical but very broadbanded. The H-loop "generally" has omni-directional characteristics where as a dipole or longwire has definite nulls and peaks around the compass. I would guess that my H-loop is about at least 70-75 meters in circumference at an average height of about 20 ft. It is strung around the edge of my roof in a large "L" configuration with the wire tucked under the roofing shingles at strategic locations - invisible! It has survived several seasons of severe weather and hasn't budged. I use it for SWLing as well as transmitting on 80-10 meters using a vintage Johnson Matchbox - sweet! Compared to a dipole or a longwire it doesn't experience those "dips" in reception on certain bands. Any "dips" that do occur are not as deep and an antenna matchbox will easily make up for it. Where anyone obtained the idea you must use dozens of 75+ ft telephone poles around 100 acres of real-estate has simply never built or used a horiz. loop. Granted, it would undoubtedly work better at greater height, my horizontal loop encircles a small section of my woods at varying heights of anywhere from 6 feet to (maybe) 15 feet. I ran about 475 to 500 feet of wire, hanging it off available tree branches as I went, in what is more or less a square with somewhat bulging sides. I couldn't tell you exactly how much wire I used, other than I used enough to form a loop through the woods. I couldn't tell you it's impedance. I feed it with coax through a home-made 1:1 transformer. I have no complaints with it's performance. I think there's this expectation by folks new to the hobby that everything has to be "labratory" perfect or it's a waste of time. In my experience, I have found that wire antenna's are *very* forgiving of imperfections. Granted, they will not perform as well as something carefully constructed in a labratory environment, but they will *still* work - and there's even odds (or better than even) they will work better than expected! My rule of thumb is: "As much wire as you reasonably can, as high as you reasonably can." In different situations, that could be 30 feet of wire at house-eave level -or- a 2wl horizontal loop at 1wl above dirt. Just do what you can, and are interested in trying, and don't sweat the details until *after* you establish a baseline. -=jd=- -- My Current Disposable Email: (Remove YOUR HAT to reply directly) |
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