Topband: Near field of a flag?
Dan Zimmerman N3OX
n3ox at n3ox.net
Mon Sep 3 13:48:24 EDT 2007
This isn't really a 160m question... or even a lower HF question, but
this is the place I know people are working with flags and other short
RX vertical arrays, and I figure any ensuing discussion would be
pertinent to topband ops.
I have a lot of neighbor noise sources across HF and in my situation
I'd like to deal with it through technology, not hunting and fixing
sources. I'm renting, and not wanting to bother the neighbors about
their noisy consumer electronics since the landlord can shut me down
if I annoy the neighbors too much.
I have a particular source on 17m and 20m that's a really annoying
pulsing switcher, and I've had okay luck with my MFJ-1026 and a
miniature flag (approx 1x2 feet) as a noise sense antenna (I built a
2N5109 preamp into the MFJ-1026 for lower noise amplification) but I'd
like to make the setup a little better and make the noise antenna
have more directivity and a little more gain so that I can get more
noise and less desired signal.
So, I'm thinking I'll try a two flag array pointed at the neighbors' house.
What I'm wondering is if I'll see any increased ***gain*** from the
array for a source *half a wavelength* away?
I figure the directivity will still help me avoid nulling desired
signals coming in from other directions, so the question is a little
academic, but am I barking up the wrong tree here in thinking the flag
will ALSO pick up more noise because it's "pointed toward the source"
or is a source a half wavelength away from a couple of flags *too
close* to infer anything from far-field patterns?
73 and thanks,
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