23709
« on: August 02, 2014, 1524 UTC »
Here's my experience, YMMV:
The perimeter (length) of the loop sets the lowest frequency where it will operate well. My loop is 670 ft (206 meters) and works down to the upper end of MW, just around one wavelength, which makes some sense. It doesn't do too bad into the middle of the MW band, but signal are quite weak in the lower end of MW. And nonexistent on LW.
As for height, mine varies a lot, from probably 20 ft on the low run s, to maybe 50/60 ft at the highest. My goal was to get as much wire in the air as possible. From theory I'd guess that higher height will favor low angle (DX) radiation. So I would not worry too much if parts of your sky loop are lower than others.
I feed mine with a 9:1 balun and 75 ohm RG6 coax. I've tried a 4:1 and 16:1 balun, they work about the same. The impedance of the sky loop various by insane amounts over all of HF, attempting to match impedance is an exercise in futility, and not critical for receiving anyway. But I strongly recommend a balun. I use RG6 because 1) it is cheap 2) you can buy long runs with weatherproof F connectors already installed and 3) life is too short to mess around with soldering PL-259 connectors. Throw an F to PL-259 on each end, with some coax seal, and you are done.
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