Paul Burridge wrote in message . ..
....
It's annoying, because the tx output Z I'm trying to match is (by a
strange coincidence) 140 ohms! So a folded dipole would be ideal, I
guess. However - and it's a big *however* - I can't use one. I'm stuck
with a telescopic whip and a ground plane the size of a box of Swan
Vestas. I imagine the radiation resistance of such a non-ideal antenna
is pretty low, but until someone can gimme a ballpark figure for it, I
can't even begin to think about how to go about matching it. :-(

Paul, it would be reeeeally helpful if you'd include enough info so we
could give you a ballpark figure. What wavelength (or frequency)?
How long is the antenna? How big is that box? (Will someone be
holding it during operation?) Yeah, someone did offer a ballpark
figure, but that depends a whole lot on what fraction of a wavelength
you have for your antenna and your ground plane. (Or perhaps the
posting in which you explained all that hasn't made it to this corner
of the universe.)

Cheers,
Tom