Topband: RX antennas
jimjarvis at comcast.net
Sat May 8 12:20:56 EDT 2004
Your friend is right about the coax loop vs. simple inverted vee.
Except, of course, the ability to get a null.
I presently have a pair of crossed k9ay loops, which work almost
as well as my TX antenna, in terms of signal levels, and provide
moderate noise reduction, and good backside nulls.
The limitation with the crossed loops, however, is WHERE the null
is pointing. Sometimes it's optimal. Often it's not. If I
could do it, I would make a SINGLE loop, rotatable. I believe that
DL2SQ markets telescoping fiberglass poles, which he packages as a
transceive loop for 20m. It's about the right size to accomodate
a k9ay loop...and the weight is such that you could mount it in
a light duty rotor, which itself is mounted on a pole stuck in the
ground. If the size isn't quite right, I'm sure you can get individual
components from Walther, to make what you need.
The rotatable AY loop would permit you to reject selected interference
while still having reasonable signal strength. If I get some time
this summer, I may go that direction.
jimjarvis at ieee.org
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