Figure 3-6 Transponder Antenna Minimum Ground Plane Radius; Gps Antenna Bonding - Garmin GTX 335 w GPS Installation Guidance

Figure 3-6 Transponder Antenna Minimum Ground Plane Radius

3.15.4 GPS Antenna Bonding

CAUTION
If the antenna is struck by lightning, the foil by itself may not be sufficient to dissipate
lightning currents. Additional protection may be needed depending on the construction of
the structure to which the antenna is attached. Refer to aircraft SRM for more information.
NOTE
For non-metallic aircraft, the ground plane can be composed of heavy duty aluminum foil
tape, such as 3M P/N 438, 3M P/N 436, or other adhesive backed dead soft foil with
aluminum 7.2 mils or greater.
Follow these precautions when planning installation of the antenna:
1. The ground plane should be 7.5 inches minimum radius around the perimeter of the antenna. Refer
to figure 3-7. For metallic aircraft, the surrounding metal skin on which the antenna is attached
supplies the ground plane.
2. The antenna baseplate must be electrically bonded to the ground plane.
3. The electrical bond must achieve direct current (DC) resistance less than or equal to 2.5 milliohms.
4. The paint on the outer skin of the aircraft, under the footprint of the antenna baseplate, should not
be removed unless it is necessary to meet bonding requirements.
190-00734-17
Rev. 1
ANTENNA
GROUND PLANE
GTX 335 w/GPS Installation Guidance
Page 3-20