Antenna Considerations; Transponder Antenna - Garmin GTX 3X5 Series Installation Manual

3.15 Antenna Considerations

Mounting location considerations for the antenna(s) are provided in this section. The recommended antenna locations
are shown in figure 3-4.

3.15.1 Transponder Antenna

Ground planes must be considered for installations on composite aircraft. Conductive wire mesh, radials, or thin
aluminum sheets embedded in the composite material supply the ground plane to maximize the antenna pattern
(gain). This can improve transponder performance.
The antenna mounting must use the aircraft manufacturer's type certificated antenna location and style. The antenna
must be installed in accordance with manufacturer instructions and/or AC 43.12-2A Chapter 3.
Transponder antenna considerations help the installer to select the best location for the antenna. The antenna should:
1. Be attached away from major protrusions, such as engines, nacelles, propellers, and antenna masts.
2. Be as far as practical from landing gear doors, access doors, or other openings that could affect its radiation
pattern.
3. Be vertically attached on the bottom of the aircraft.
4. Not be attached within three feet of the
5. Not be attached within six feet of a DME antenna.
6. Be attached a minimum of three feet from the GTX 3X5 to prevent RF interference.
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Rev. 9
ADF
sense antenna or any other communication antenna.
GTX 3X5 Transponder TSO Installation Manual
Installation Overview
Page 3-24