starman wrote in message ...
Mark Keith wrote:

It's the improved decoupling of the feedline
from the antenna that reduces the noise level. "noise ingress" Not
the grounding itself, although the grounding helps in the decoupling
of the line.

I think we're talking semantics here, but how else could you decouple
the feedline of an inverted-L antenna other than using an effective
(short) earth ground connection?

As one mentioned, radials. Or you could use a choke,beads, etc. Lets
say you had a 1/4 wave ground plane that was elevated with a set of
radials. The radials will decouple the feedline pretty well. There is
no need to ground the radials, or the supporting mast, except as a
lightning concern. A choke will decouple the line fairly well. Noise
ingress has nothing to do with being grounded or not. It's an issue of
decoupling the feedline from the antenna. Using a ground connection
under an "L" will decouple it fairly well, but it's just one method
that can be used, and the "ground" is not a required element. It's not
just semantics, because an "rf ground" is not a requirement of good
decoupling. But saying that, I usually do ground the low end of inv
L's. MK