Com Antenna Location - Garmin GIA 63 Installation Manual

2.2.3

Com Antenna Location

The GIA 63(X) COM antenna should be well removed from all projections, engines and propellers. The
ground plane surface directly below the antenna should be a flat plane over as large an area as possible (18
inches square, minimum). The antenna should be mounted a minimum of six feet from any DME or other
COM antennas, four feet from any ADF sense antennas, three feet from the GIA 63(X) and its GPS
antenna, and as far as practical from any ELT antennas.
If simultaneous use of two or more COM transceivers is desired, the COM antennas must be spaced for
maximum isolation. For a two COM installation, one COM antenna should be mounted on the top of the
fuselage and the other antenna should be mounted on the bottom of the fuselage. For installations with
three COM's, one COM antenna should be mounted on the top of the fuselage and the other two antennas
should be mounted on the bottom of the fuselage and physically separated from each other as much as
possible.
Simultaneous COM performance varies significantly across installations and is affected by both the
isolation between the COM antennas and the separation of the tuned frequencies. Each installation should
be individually examined to determine the expected performance of simultaneous COM.
2.2.4 VOR/LOC Antenna Location
The GIA 63(X) VOR/LOC antenna should be well removed from all projections, engines and propellers. It
should have a clear line of sight if possible. The antenna must be mounted along the centerline of the
aircraft, minimizing the lateral offset.
2.2.5 Glideslope Antenna Location
The GIA 63(X) Glideslope antenna should be well removed from all projections, engines and propellers. It
should have a clear line of sight if possible.
2.2.6 Electrical Bonding
No special precautions need to be taken to provide a bonding path between the GPS antenna and the
aircraft structure. Follow the manufacturers' instructions for the COM, VOR/LOC and Glideslope
antennas.
2.2.7 VHF COM/GPS Interference
On some installation VHF COM transceivers, Emergency Locator Transmitter (ELT) antennas, and
Direction Finder (DF) receiver antennas can re-radiate through the GPS antenna. The GIA 63(X) COM
does not interfere with its own GPS section. However, placement of the GA 56 GPS antenna (or other
comparable antenna) relative to a COM transceiver and COM antenna (including the GIA 63(X) COM
antenna), ELT antenna, and DF receiver antenna is critical.
Use the following guidelines, in addition to others in this document, when locating the GIA 63(X) and its
antennas.
• GPS Antenna—Locate as far as possible from all COM antennas and all COM transceivers
(including the GIA 63(X) COM), ELT antennas, and DF antennas. The GPS antenna is less
susceptible to harmonic interference if a 1.57542 GHz notch filter is installed on the COM trans-
ceiver antenna output.
• Locate the GIA 63(X) as far as possible from all COM antennas.
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Rev. Y
GIA 63 Installation Manual
Page 2-9