Merry Christmas everyone.
I have a Garmin 327 transponder and a short antenna with a small ball on
the end. When I installed it, Bob Nuckolls advised that the ground plane
should to be an aluminum disc the radius of which is the same as the
length of the antenna. So my disc is probably 5-6 in diameter. It seems
to work OK, around this area at least which is about 10 nm from ATC.
Looking at upgrading to the Dynon Transponder in order to meet the 2020
NextGen requirement here in the States. Reading the install instructions
it says:
<<The ground plane should be as large as you can sensibly make it.
Because it is a function of the wavelength of the transmission, the
smallest practical ground plane for a transponder is a square around 120
mm per side; as the size increases the performance improves until the
ground plane is around 700 mm on each side. Anything much larger than
that size is unlikely to show significant further improvement.>>
So my disc is slightly larger than the 120 mm square referenced but
according to Dynon the bigger you make it the better the performance.
As I have plenty of room, is there any merit in increasing the size of
the ground plane? What have others done - particularly for a Dynon set up?
Regards,
Martin Tuck
Europa N152MT
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