Garmin GTR 200 GTR 200 Installation Manual - Page 25

Antenna Installation and Connections, Antenna Coaxial Cable Installation - com radio

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3.5 Antenna Installation and Connections The GTR 200 requires a standard 50  vertically polarized antenna. Follow the antenna manufacturer's installation instructions for mounting the antenna. The antenna should be mounted on a metal surface or a ground plane with a minimum area of 18 inches x 18 inches. Refer to Section 2.5.1 for installation location considerations. 3.5.1 Antenna Coaxial Cable Installation The antenna coax cable should be made of RG-142B, RG-400 or a comparable quality 50  coax. Follow the BNC connector manufacturer's instructions for cable preparation/connector installation. Check that there is ample space for the cabling and mating connectors. Avoid sharp bends in the antenna cable, and routing near aircraft control cables. Route the COM antenna cable as far as possible away from any GPS antenna cables. Check for insertion loss and Voltage Standing Wave Ratio (VSWR). VSWR should be checked with an in-line type VSWR/wattmeter inserted in the coaxial transmission line between the transceiver and the antenna. The VSWR meter should be inserted as close to the transceiver as possible. When rack and harness buildup is performed in the shop, the coax termination may be provisioned by using a 6-inch inline BNC connection. This would be an acceptable place to insert the VSWR meter. Any problem with the antenna installation is most likely seen as high reflected power. A VSWR of 3:1 may result in up to a 50% loss in transmit power. VSWR at the low, mid and high end of the tuning range should be less than 3:1, for best performance VSWR should be less than 2:1. A high VSWR decreases the amount of power radiated by the antenna and increases power supply current and heat dissipated by the radio when the radio is transmitting. 190-01553-00 Rev. A GTR 200 Installation Manual Page 3-3

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190-01553-00
GTR 200 Installation Manual
Rev. A
Page 3-3
3.5
Antenna Installation and Connections
The GTR 200 requires a standard 50
vertically polarized antenna.
Follow the antenna manufacturer’s
installation instructions for mounting the antenna.
The antenna should be mounted on a metal surface or a ground plane with a minimum area of 18 inches x
18 inches. Refer to
Section 2.5.1
for installation location considerations.
3.5.1
Antenna Coaxial Cable Installation
The antenna coax cable should be made of RG-142B, RG-400 or a comparable quality 50
coax.
Follow
the BNC connector manufacturer’s instructions for cable preparation/connector installation.
Check that there is ample space for the cabling and mating connectors.
Avoid sharp bends in the antenna
cable, and routing near aircraft control cables.
Route the COM antenna cable as far as possible away from
any GPS antenna cables.
Check for insertion loss and Voltage Standing Wave Ratio (VSWR).
VSWR should be checked with an
in-line type VSWR/wattmeter inserted in the coaxial transmission line between the transceiver and the
antenna.
The VSWR meter should be inserted as close to the transceiver as possible.
When rack and
harness buildup is performed in the shop, the coax termination may be provisioned by using a 6-inch in-
line BNC connection.
This would be an acceptable place to insert the VSWR meter.
Any problem with
the antenna installation is most likely seen as high reflected power.
A VSWR of 3:1 may result in up to a
50% loss in transmit power.
VSWR at the low, mid and high end of the tuning range should be less than
3:1, for best performance VSWR should be less than 2:1.
A high VSWR decreases the amount of power
radiated by the antenna and increases power supply current and heat dissipated by the radio when the radio
is transmitting.