On Monday, March 16, 2015 at 7:26:04 PM UTC-4, Jonathan St. Cloud wrote:
Was wondering if all transponder and ADS-B units require an external antenna to be mounted on the beautiful flowing lines of a glider? Is there a way to have an internal antenna?

Well, it depends. Metal gliders have to have external antennas for everything
since they're natural Faraday cages. Fiberglass gliders are transparent to
the microwave frequencies, so they can have internally mounted antennas.
More modern carbon fiber gliders are Faraday cages, but they often have
fiberglass tails to accommodate internal antennas. Still, I've seen
external transponder antennas on modern gliders.

Matt