JJ, please don't use RG-58 for a transponder cable - it has very high
attenuation per foot. Times Microwave LM240 is a much better choice,
with only 1/3 of the attenuation of RG-58 at 1 GHz. I usually use
Times Microwave LM300, with only 1/4 the attenuation of RG-58, but it
has double the diameter. Both of these cables have a greater than 20
year life outdoors.

-john

On Feb 6, 9:07 am, JJ Sinclair wrote:
I second the L-2, di-pole antenna suggestion, all inside with nothing
sticking out to get ripped off. Carve a1"X 1"X4" balsawood block so
that it matches the inside curve of your non-carbon fuselage, then
glue the antenna vertical to the flat side and the curved side to the
inside aft fuselage. Keep it about 6" away from metal objects like
your elevator push-rod, etc. Secure the RG-58 lead so that it can't
get tangled with controls and you're good to go.
Hope this helps,
JJ