Topband: QST Jun 06 RX Loop
jsm at gulfislands.com
Mon May 15 14:26:16 EDT 2006
>Loops receive propagated waves omni-directionally, so once the loop is set
for maximum local noise nulling, further rotation will not significantly
benefit propagated wave reception.
That is what I had been led to believe as well before building and using a
number of shielded and air-core tuned loops for LF and NDB work. Although I
haven't measured the null depths, I have noted significant nulls on many
skywave signals, especially the further ones.
> My coax loops were great disappointments, with an absence of a deep, sharp
null, and a lack of sensitivity. Rotating these loops with a rotor will
verify their poor performance.
Again...a number of shielded / amplified LF loops built using RG-8 for the
loop element have yielded deep nulls on both groundwave and skywave signals.
Perhaps there are other variables coming into play....arrival angle,
location of nearby metal or antenna structures, construction quality, loop
balance, feedline isolation....guess that's what makes loops so interesting!
Steve / VE7SL
Web: "THE VE7SL RADIO NOTEBOOK" at http://www.imagenisp.ca/jsm
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