ELT Antenna Placement

[N190YX]

Regarding the placement of the com antenna, I contend the bottom of the fuselage is the ideal location because 1) aerodynamically, the air is moving faster on top versus on the bottom of the fuselage, so less drag; 2) aesthetically, fewer antennas on top of the fuselage looks better; 3) no ground plane issues either way; 4) ground communications work fine with a bottom mounted com antenna, the landing gear does not interfere with transmission or reception, I have had one on the bottom of my certified airplane for decades and have never, repeat, never had a communications problem during ground operations at my control towered home base or during ground operations at any airport anywhere. Also works fine in the air. I highly recommend placement of com antennas on the bottom of the fuselage. 45 degree or 90 degree bent antennas, attaching photos of a couple samples from Aircraft Spruce. Mine is a 90 degree bent antenna.

[Scott Todd]

FWIW, faster moving air is more drag....Its actually a function of the velocity squared.

[builderflyer]

Regarding the placement of the com antenna, I contend the bottom of the fuselage is the ideal location Mine is a 90 degree bent antenna.

I absolutely agree with the above conclusion despite what the naysayers may conclude. My Sonex has had a belly antenna since day one and it was based on a towered airport for its first ten years without a hint of ground communications issues, no matter where located on the airport. And, in the air it may even be more effective than a top mounted antenna since there is a lot less aluminum in the way between the belly antenna and a receiving ground station. All the antenna theory out there can't be used to argue against success.

Art,,,,,,,,,,,,,,,,,,,Sonex taildragger #95,,,,,,,,,,,,,,,,Jabiru 3300 #261