Antenna ground planes for composite aircraft

On Sun, 20 Dec 2009 17:50:02 -0600, brian whatcott
wrote:

rich wrote:
Here's the article: http://www.express-builder.com/docs/tip1/tip1.pdf
written by Bob Archer. /snip/ Also if you were planning to go with Jim
Weir of RST's designs don't bother with the ferrite beads.
/snip/
My antenna designs do not need a balun because I use
a modified version of a feed called a Gamma match that feeds the
antenna at the fifty ohm point...

Hmmmm. so this is a fellow with another antenna design, bad-mouthing the
opposition. It makes about as much sense as my giving you this advice:

Yeah, I know. Daddy taught me that if you can't say anything nice
about somebody, then don't say anything, which is why I've never
commented on the Archer designs.



"If you were planning to go with Bob Archer's design, don't bother with
the gamma match lengths he uses..."

What DOES make sense, is that if you really do follow Archer's advice to
rig a dipole hooked directly to the coax - you guarantee standing waves
on the outer (sheath ). A balun is what matches this dipole
arrangement to coax...

But since we aren't trying to squeeze the last fraction of a dB out of
the arrangement, and even though a balun still guarantees SOME
reflected power except at the precise center frequency of the antenna,
then simply connecting the dipole ears to the coax and stripping the
reflected power from the sheath with single-turn chokes in the form of
ferrite beads slipped over the coax right at the antenna does a
credible job of making a simple, lightweight, and nearly bulletproof
antenna.

Jim