"Owen Duffy" wrote in message
...
"Sal M. Onella" wrote in
:

Back on topic, I am using the sleeve in a conventional dipole
configuration until I can take the time to apply the ideas presented
in this NG. I noticed this afternoon that coiling four turns of
decoupling loop a few feet from the feed actually raised the VSWR,
which I didn't understand. Also, where the coax hangs down next to
the antenna makes a difference in the VSWR, so obviously the line is
not "flat" and is instead part of the antenna. (Do we still use the
term "flat" to describe a transmission line which is properly matched
to the load? I recall it from Navy training more than 40 years ago.)
My first HF antenna works, but it's clearly no marvel.

I just read your first posting. It sounds like you are building what I
refer to as a coaxial dipole. The key to success with coaxial dipoles is
decoupling the feedline. A common configuration is to place a set of
radials, or a quarter wave choke to be effective a quarter wave below the
bottom of the dipole lower element... this actually attempts to reduce
current below the radials, and uses the quarter wave of feedline above
the radials as part of the radiator for a little more gain.

IIRC, the ARRL had some suggestions about decoupling a coaxial dipole.

Owen

I was thinking it might be interesting to make a ferrite choke that you can
slide on the coax to tune the antenna. You might not have to slide the whole
choke just a bead or two that you can move a few inches.

Jimmie.