What Orval says is true, theoretically. The ground plane should extend in all
directions from the base of the antenna a quarter-wave. For the com band this
is about 22", and the antenna should be in the dead center of this sheet of
metal.

Having said that, an airplane is a bunch of compromises flying in loose
formation. If you can't get this size, or the antenna needs to be off-center,
then it won't be perfect. But it will "work", whatever that means.

Jim





Orval Fairbairn
shared these priceless pearls of wisdom:

-
-The ground plane should, at a minimum, extend in all dierections from
-the base of the antenna, at least one antenna length. Yes, it does make
-a difference if the antenna is not at the center of tthe ground plane --
-it will alter your radiation pattern.

Jim Weir (A&P/IA, CFI, & other good alphabet soup)
VP Eng RST Pres. Cyberchapter EAA Tech. Counselor
http://www.rst-engr.com