On mine, I mounted a telescoping BC band replacement antenna at the top
of the metal body piece just behind the door and collapsed it down to
about a quarter wave on 2 meters. Although you could probably fiddle the
antenna length to get a fair match, I built a little highpass T network
out of an inductor on a small powdered iron core and a couple of trimmer
capacitors to do the matching. The pattern is probably pretty skewed,
but it's adequate to reach the local repeaters. You could mount a dual
band antenna at that same spot with some sort of right angle mount.

A half wave antenna at the top of the roof should work ok, but even with
a half wave antenna, there's a small amount of return current that has
to go somewhere. If I were willing to punch a hole in the top (which I'm
not -- have you seen what a replacement top costs?), I'd do something
like put a small ground plane inside the car against the top.

This might be a reasonable application for a through-glass antenna --
through one of the windows, that is, although it might be interesting to
see how one would work as a through-the-top antenna if you could rotate
it to be vertical. But having spent quite a few hours studying various
patents for their design, it looks like some might work much better than
others.

Roy Lewallen, W7EL

Harbin wrote:
Howdy Y'all:

I have a fiberglass roof on my Landcruiser, and I was wondering if I can use a halfwave roof mounted antenna?
For some reason, I think since the halfwave is end loaded, that it will not work on my fiberglass roof, and that
it uses a steel roof as part of the match. Am I wrong here? The only other thing I can think of is some kind of
stainless steel J pole on a mount coming off the back. And what about a dual band that will work on fiberglass?
Anybody work with this problem before?

SeeYaa Harbin