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2.5.1
Antenna Coaxial Cables (Requirements and Fabrication Guidance)
The GRA 5500 requires a minimum of two coaxial cable assemblies (each coaxial cable assembly consists
of a coaxial cable and a connector properly terminating each end of the coaxial cable) assembled with the
same type of coaxial cable for connection from the radar altimeter antennas to the LRU transmitter (TX)
and receiver (RX) ports. If multiple coaxial cable assemblies must be used with adapters in order to
connect the unit ports to the antennas, all assemblies must use the same type of coaxial cable. Although
the use of adapters (both right angle and straight) may be unavoidable when addressing certain
installations, minimal use of adapters in the installation is recommended whenever possible.
NOTE
Any in-line or bulkhead penetrations must be evaluated separately from the coaxial cable
assemblies and require special consideration. It is the responsibility of the installing
agency to show airworthiness of the installed coaxial cable assemblies (whether
fabricated or purchased).
The requirements for the RF transmission lines made of coaxial cable assemblies used to connect the GRA
5500 TX and RX ports to the radar altimeter antennas are as follows (see
NOTE
For the purpose of this document, an RF transmission line is defined as either a single
coaxial cable assembly used to connect a unit TX or RX port to its respective antenna port,
or a number of coaxial cable assemblies and adapters used to connect a unit TX or RX
port to its respective antenna port. It is the responsibility of the installing agency to
ensure that the RF transmission lines and associated coaxial cable assemblies meet the
following requirements in order to comply with the system installation standards.
1. The maximum total RF loss of each RF transmission line (made up of one or more cable
assemblies with adapters) must not exceed 5.0 dB at 4.3 GHz.
2. The maximum total length of each RF transmission line (made up of one or more cable assemblies
with adapters included in the length total) must not exceed 30 feet.
3. The minimum total length of each RF transmission line (made up of one or more cable assemblies
with adapters included in the length total) must not be less than 1 foot.
4. All coaxial cable assemblies making up the RF transmission line must have a Voltage Standing
Wave Ratio (VSWR) of less than 1.5:1, at each connector, at a frequency of 4.3 GHz.
5. The RF transmission line used to connect the unit to the antennas must have a total Voltage
Standing Wave Ratio (VSWR) of less than 1.5:1, at each of the two end connectors of the
assembled RF transmission lines, at a frequency of 4.3 GHz.
The VSWR of any adapter used to complete the assembly of an RF transmission line must be compliant
with the adapter's manufacturer specification at 4.3 GHz.
190-01277-00
Rev. A
Figure
2-5):
GRA 5500 Installation Manual
Page 2-11
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