>from Mark, N5OT [answers follow questions]
> Question 1 - I have seen plots on K9AY loops and their relative gain is
> way down on 160 compared to 80. Of course, they work great on 160,
> certainly with a preamp. Does this mean you could make one for 80 that
> was half the size and it would still work well? Is there something
> magical about the size that Gary designed them to be?
Nothing magical about the size -- as a loop, the signal capture is
proportional to the enclosed area, and the published dimensions are the
maximum that allow it to work on 80M with a simple resistive termination. So
yes, you can make a smaller loop for any frequency and use more preamp
gain -- until the point where its inefficiency keeps you from reaching the
band noise floor.
> Question 2 - is there any reason you could not build one 10 feet above the
> ground and use a ground plane of 3 or 4 elevated radials? Over very
> sandy/rocky soil, wouldn't that give me better control of my antenna
> ground than (more) difficult-to-manage (i.e. hard to bury and keep buried)
> in-ground radials?
There have been reports of successful -- and unsuccessful -- elevated
installations with radials on a garage, carport, even an aluminum pool
cabana. If you try radials, the first four should be directly under the loop
wires for maximum counterpoise effect.
For a height of 10 feet, you can simply use a wire straight down to a
ground rod. Make sure it's straight down -- symmetry is important to keep
the extra vertical wire length from having a big effect. Back a few years, I
tried a loop raised to 7 feet and it worked fine, with no changes detected.
73, Gary
K9AY
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