Installation Instructions

190-01007-A3 GTN 6XX/7XX AML STC Installation Manual
Rev. 4 Page 2-21
2.4.4.4 Ground Plane
Ensure that the GPS/NAV/COM antennas are electrically bonded to the aircraft. Follow the aircraft
manufacturers’ instructions for the NAV and COM antenna installations, or obtain other FAA approval.
The GPS/WAAS antenna requires a minimum ground plane radius of 7.5 inches around the perimeter of
the antenna. Refer to Figure 2-7. For metal aircraft, the surrounding metal skin on which the antenna is
mounted supplies the ground plane. For non-metal aircraft, the ground plane can be composed of heavy
duty aluminum foil tape, such as 3M P/N 438 or other adhesive backed dead soft aluminum foil minimum
0.012 inches thick. It should be noted that 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 mounted.
7.5 IN. MINIMUM
GPS ANTENNA
GROUND PLANE
Figure 2-7. GPS/WAAS Antenna Minimum Ground Plane Radius