I installed a prototype 40m Horizontal loop for testing in a recent contest. This was a test to see if a low-elevation loop would be useful for NVIS propagation, as I was trying to maximize the number of close-in stations I could work. If it showed promise, it might be something I would use for next year’s VA QSO Party.
I mounted the loop at only about 12-15′ above the ground. I originally planned to feed it with coax at one of the corners. Models indicated that this would be useable on 40m, but the SWR would probably be too high for use on other Bands. I had some 450-ohm ladder line lying around, so I fed it with that instead. With a decent Tuner, that should make it usable on other Bands as well as 40m.
I took some initial SWR readings and had a surprise. The initial frequency for minimum SWR was too high – about 8.5 MHz. I figured that adding a few feet to the loop would bring the frequency down, closer to the 40m Band. I added about 4′ but did not see a significant change in the minimum-SWR frequency. Have not figured that out yet, maybe it is due to the shape (very long/narrow rectangle) and/or the proximity to the ground??
I brought the ladder line to a balun, then coax into the shack. I fed this to my new Elecraft KAT-500 Tuner and it was usable on 20 and 40 meters. So I planned to use the loop along with my other 2 antennas in the contest.
The loop was not a great performer overall, but it did succeed in netting a few close-in contacts that I could not make with the other antennas. So I will consider using this in the VA QSO Party if I decide to take on a fixed effort this year.
Next I want to get the shape closer to a square, and get it up to 40′ elevation, so I can see what it can really do for longer paths. I know several people that have had great success with loops, and I am hoping this will make a good addition to my modest antenna farm.
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