On 2/24/2021 12:33 PM, Don Kirk wrote:
As I have mentioned in a few other responses I suspect having the short
10 foot feedline helps to negate common mode noise
YES!
and direct signal
ingress into the feedline that often haunts us. I do have one
recommendation about pattern distortion as follows. Check to make sure the
peak and the null of the antenna are in agreement on the signal you are
direction finding. If you notice a slight skew (where they don't agree
with each other), then move away from existing objects and this will
correct that problem. I sometimes notice a slight skew when in my backyard
near my house (looks like the null shifts slightly from where it should
be), and when I get out away from my house (I move to the sidewalk in front
of my house) the slight pattern skew goes away.
Yes again! Rudy, N6LF, has shown that even relatively short towers that
are nowhere near resonance can skew the pattern of a nearby vertical. My
120 ft tower with the small 3-el straight SteppIR and a long-boom 6M
Yagi acts as a passive reflector to my Tee vertical that's 200 ft from
it. Before I added chokes top and bottom to the feedlines of my high
dipoles, they degraded that Tee.
In general, the most sensitive parts of an antenna's pattern are its
null(s), because they are the result of the cancellation of two nearly
equal complex numbers that must be equal in both magnitude and phase.
73, Jim K9YC
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