I have a Velocity - and am planning on using a Comant CI-105
transponder antenna, and place it out on the wing strake area - as I
do not want it close to the engine and near my AHRS setup.

As this airplane is a glass airplane, and this antenna requires a
ground
plane - I have read about a "tuned" ground plane.

The suggestion was to make a 5.2" disc - @1090Mhz, 1/2 wave is
5.15229..."

Can someone give me a heads up as to what a tuned ground plane really
is?

Thanks,

John