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Antenna Grounding for Composite Aircraft
General Information
Installations must be made by qualified personnel, and in accordance
with Federal Regulations. Refer to FAA Advisory Circular 43.13-2A
for General installation guidelines. A copy of the FAA Advisory
Circular can be obtained at www.faa.gov.
Look for Advisory Circulars under the Regulatory/Advisory heading
on the FAA home page.
Mounting Preparation
The electrical bonding of the antenna to the aircraft ground is
extremely important. If this is not done properly, antenna performance
characteristics may become distorted and nulls may appear in the
antenna radiation pattern. This, in turn, may cause erratic navigational
readings or signal drop out. The electrical bonding of antennas
to composite aircraft is best accomplished by direct metal-to-metal
contact of the antenna mounting hardware to an internal ground plane.
To do this, you must have the mounting screws, washers and nuts
make direct contact to the internal ground plane with the use of
a backing plate. The backing plate must make direct contact to the
internal ground plane. Sandwich the aircraft skin and internal ground
plane between the antenna base plate and internally mounted backing
plate. To test the electrical bonding of the blade to the aircraft,
a reading of .003 ohms between the antenna base plate and ground
should be achieved.
Ground Plane Size
VHF antennas will require a metal ground plane size of 24”
by 24” OR LARGER. “As large as practical” will assure
optimum antenna performance. Most other antennas may also use the
24” by 24” rule, but with ground planes, larger is always
better.
After installation, double check that a reading of .003 ohms between
the antenna base plate and ground has been achieved.
WARNING:
Comant Industries, Inc. cannot be held responsible for the applicability
of this Guideline for specific aircraft and/or specific antennas.
It is the Installers responsibility to assure proper applicability,
and, that the antenna is properly installed. Always refer to Comant's
installation drawings before drilling holes and when referencing
antenna performance characteristics. Installations should only be
made by qualified personnel.
General
Antenna Installation Guidelines
GPS
Antenna Installation Guidelines
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