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Old November 18th 07, 10:36 PM posted to rec.radio.amateur.antenna
Roy Lewallen Roy Lewallen is offline
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First recorded activity by RadioBanter: Jun 2006
Posts: 1,374
Default Low Noise receiving Loop antenna

Tony Giacometti wrote:

And to think I was just trying to build a simple low noise receiving loop

Lets try this question.....

if I were to start from scratch.......

and I wanted to build a low noise receiving loop......

what style of low noise loop would you suggest I build?

OR is there another solution to my situation on my 1/3 of an acre lot?


What you should do is realize that there is no such thing as a "low
noise receiving loop". No antenna has any way to tell the difference
between signals and noise, so a "low noise receiving loop" is also just
as much a "low signal receiving loop". All a loop can do that might help
with a noise problem is provide a sharp null in one direction (actually,
two, but it's very unlikely that both will be useful at the same time).
If the noise is coming from a single narrow direction, you can turn the
loop to reduce it. If the noise isn't coming from one narrow direction,
a loop won't be "low noise" and, as I pointed out earlier, might well be
worse than an outside antenna if the noise is being radiated by house
wiring.

From all the descriptions, it sounds like your main problem with the
loop is that the overall gain of your loop + receiver is simply too low
for comfortable listening. What you need in order to provide the
necessary additional gain is either a better impedance match between the
loop and receiver (for which there have been multiple suggestions), an
amplifier either ahead of the receiver (a preamp) or after the receiver
(an audio amplifier), or some combination of those. If you can null out
the noise by turning the loop, then the additional gain will get you
what you're trying to achieve. If not, then a loop isn't the solution,
and the only solution might be to find and eliminate the source of the
noise.

Roy Lewallen, W7EL