INITIAL INSTALLATION MANUAL
AF INTEGRA / AF-H INTEGRA
PAGE: 16
JUN 01/2011
of antenna radiation patterns. Detuning of the 121.5 MHz antenna may be
required avoid the effects of radiated inter-modulation products which may
be possible from non-operating 121.5 MHz ELTs exposed to high levels of
RF energy.
Idealistically, for the 121.5 MHz ELT antenna, 2.5 meter separation is
sufficient separation from VHF communications and navigation receiving
antennas to minimize unwanted interference. The 406 MHz ELT antenna
should be positioned at least 0.8 m from VHF communications and
navigation receiving antennas to minimize interference.
External antennas, which have been shown to be compatible with
particular ELT will either be part of the ETSO/TSO'd ELT or will be
identified in the ELT manufacturer's installation instructions.
Recommended methods for installing antenna are outlined in FAA AC
43.13-2B. The Antenna should be mounted as close to the respective ELT
as practicable."
B. Antenna installation procedure
The antenna must be mounted on the top of the aircraft to assure maximum
visibility of satellites. The upper aft portion of the fuselage should be preferred.
It should be mounted away from projections such as a propeller, tail surfaces,
or the shadow of large antennas. It is the responsibility of the installation
agency to determine the appropriate and adequate antenna installation.
Locate a position on the fuselage according to
Section (2) RTCA DO-204
Recommendations for external antenna location, page 15
:
A double plate may be necessary for the antenna to meet rigidity specifications
in
Section (2) RTCA DO-204 Recommendations for external antenna location,
page 15
.
A 9 Kilogram force (20 pound force) applied in all direction should not cause an
appreciable distorsion in the aircraft skin.
Each of the approved antennas requires a ground plane. On fabric-covered
aircraft or aircraft with other types on nonmetallic skins, a ground plane must
be added. This can be accomplished by providing a number of metal foil strips
in a radial position from the antenna base and secured under the fabric or wood
skin of the aircraft. The length of each foil radial should be at least equal to the
antenna length and width at least 1 inch due to the diameter of the antenna. The
ground plane must be connected to the shield of the antenna connector.
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