Roy Lewallen wrote in
:

Owen Duffy wrote:
. . .
If you try something beside a shielded loop, make sure you use an
effective means of isolating the feed line from the loop so that
pickup on the feedline does not feed the receiver.
. . .

In my limited experience, it's extremely difficult or impossible to do
a good job of isolating the feedline from a small loop. The common
mode impedance is just too high.

Roy Lewallen, W7EL


Hello Roy,

I have a small loop with inexpesive voltage balun, and it gives a quite
deep null (though I can't put dB figures on it off hand), and very sharp
null.

I wonder if the reason that Tony perceives that the nulls are shallow is
that he is assessing it on band noise. If so Tony, you should assess the
depth of the nulls on a local (ie low elevation) point source that is
much stronger than band noise. The test signal should dominate the
receiver.

If an antenna with deep nulls doesn't reduce band noise much, it
suggests that the noise is not mainly from a single direction... as
discussed earlier in this thread.

Owen