I recently installed a SkyGuard UAT ADS-B transmitter in the back of my Cozy and have it working with the supplied foot long J-pole antenna suction cupped to the back cabin window.

I would like to have the antenna somewhere on the back floor. I could put a 1/4 wave whip and ground plane like I have up front but I don't like the big ground plane and that it sticks through.

Looks like this is a nice antenna that can easily be home brewed and will work well under the back seat. See: http://lea.hamradio.si/~s53mv/avionics/tranant.html

It was designed specifically for a transponder in a fiberglass airplane by a very talented RF designer that flies a motor glider. He has lots of other neat stuff he made for his glider: http://lea.hamradio.si/~s53mv/avionics/avionics.html

I might scale his design for 978 MHz, but as it is it will probably work. I thought this would be of interest to anyone that has not yet installed a transponder in their canard, or anyone installing ADS-B out. There are some even more compact, completely flat ones, but not with full instructions for fabrication.

Del Schier
Cozy IV N197DL
Acro Sport II N105JE
Ex LongEZ N103JB
Cannon Creek Airpark 15FL