On Jan 29, 6:30 pm, wrote:
I installed an L2 antenna in the forward side wall of my cockpit
(LS-8) with my Becker transponder. I attached it to the side of the
cockpit with velcro. It has worked perfectly. The Reno tower reads
my transponder in all orientations to the tower and has no problems
when I am circling. The antenna will work with any placement as long
as there is no carbon in the panel the antenna is mounted on.

Guy Acheson "DDS"

The main thing is peopel are using transponders, fantastic (esp.
around places like Reno).

But as for "any placement" SSR radar transponder signals are
vertically polarized. So for best performance you should have the
antenna aligned roughly vertically, as opposed to say lying along the
longitudinal axis of the glider. Even though average power levels are
low I personally would not position a transponder antenna close to my
body.

My advice, as mentioned before, is to look up and try to follow the
glider manufactured recommended installation procedure. Schempp-Hirth
publishes transponder antenna information for their aircraft including
the Discus CS. In this case they recommend an external stub antenna.

The key issue raised in the original post was "test results" - lots of
do it yourself transponder installs all report "it works fine". The
problem is without really complex (=impractical) measurements it is
really difficult to determine how well an antenna install is really
working.

Once concern with dipole antennas is interference from metallic
objects like landing gear structures close to the antenna.
Conventional quarter wave antennas have a benefit of being relatively
easy to shield from these by their ground plane. But as long as the
dipole antenna is a few antenna lengths away from metallic objects you
should be fine.

Darryl