Topband: 4 sq k9ay loops for topband
n4zr at contesting.com
Mon Mar 13 09:48:42 EST 2006
At 07:27 AM 3/13/2006, Jim Jarvis wrote:
>>From the website Kaz provided it appears to be 4 active crossed-pair k9ay
>Kaz, am I correct in my understanding? How did you feed the 4 pairs
>of loops? What were the phase relationships? How did you select directions?
>That is, what control did you use? Some details would be helpful.
>My own experience with a single pair of crossed k9ay loops was that their
>principal benefit was a sharp null. If an offending station happened to
>land within that null, it was useful. Otherwise, it was not. That led
>me to conclude that a single rotatable k9ay loop was better.
>At w2gd, the k9ay loop was far inferior to our beverages. But having a
>phased array of them might be highly useful, particularly if they are
>n2ea at arrl.net
>op @ w2gd
For this topband season I set up a pair of K9AY loops, each pointed toward Europe, spaced 130 feet end-fire and phased 180 degrees. I chose the phasing because of ease of execution and to avoid misphasing as a result of impedance mismatches, which I knew I would have. The resulting array was quite effective by my lights, certainly better than a single K9AY loop, with a considerably narrower forward lobe and deepish nulls off the sides, at the cost of a somewhat reduced F/B ratio.
I am considering next year putting up a third support and arranging switching so that I can use end-fire pairs of K9AY loops in 4 directions - 45 degrees, 135 degrees, 225 degrees and 315 degrees. The models show an RDF roughly like a 1.5 wavelength beverage, but I think I'm skeptical enough to wait and see (and wonder about my modeling).
73, Pete N4ZR
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