On Friday, July 19, 2019 at 6:19:07 PM UTC-4, George Haeh wrote:
Assuming a carbon fiber fuselage, I'd put the transponder and
PowerFLARM A antennae in the fin. The COM antenna is in the rear of the fin.
There should be one foot separation among the antennae.

Except, it's impossible to achieve required spacing for all 3 in the fin,
(COM, transponder/ADS-b, FLARM) even very large gliders.
If you put the FLARM antenna in the fin, you'll need to put the
transponder antenna on the fuselage in the vicinity of the gear.
If you put the transponder antenna near the FLARM antenna (as in
both in the fin), you will fry the FLARM receiver.
Details of required spacing are in the FLARM manual.

Also, if you put the FLARM antenna in the fin, you will need to
specify the country it where will be used, as the different frequencies
required by different countries will require different antennas.

Some manufacturers have been happy to put all the antennas in the
fin when requested by the customer. The customer may not have been
too happy with the outcome.

Hope that helps,
Best Regards, Dave