Installed the transponder antenna to the doubler plate. This is located on passenger side just behind baggage bulkhead. I used a bead of clear DOW sealant between the skin and antenna and fastened the antenna in place with lock nuts. This antenna will operate on the 1090mhz Extended Squitter range and will be connected to the Garmin GTX 23ES remote transponder which will provide ADS-B Out. I have also installed another doubler plate behind the pilot side in anticipation of a similar antenna on 978 MHZ to feed a Garmin GDL 39 for ADS-B In source .