User's Manual

Exalt Communications, Inc.
Exalt i-Series Installation and Management Guide
5000001 61
2007-04-15
every frequency, there is a maximum diameter cable that supports the operating
frequency. Verify the specifications. This should is determined in the path and site
planning process.
In some cases, the choice of transmission line is not coaxial cable, but is instead air-
dielectric waveguide. This is an expensive solution and is generally not necessary, but
may be required for very long transmission line runs, and/or very long link distances,
and/or for systems requiring extremely high reliability.
Table 8 lists representative samples of transmission line types recommended for the Exalt
Digital Microwave Radio.
Table 8 Recommended transmission line
Manufacturer Type Description
Loss at
2.4GHz
Loss at
4.9GHz
Loss at
5.3GHz
Loss at
5.8GHz
Andrew LDF4-50 1/2-inch solid shield 3.3dB/100ft. 5.6dB/100ft. 5.7dB/100ft. 6.0dB/100ft.
Andrew LDF4.5-50 5/8-inch solid shield 2.5dB/100ft. 4.3dB/100ft. 4.4dB/100ft. 4.7dB/100ft.
Times LMR-600 1/2-inch braided shield 4.3dB/100ft. 6.8dB/100ft. 6.9dB/100ft. 7.3dB/100ft.
Times LMR-900 5/8-inch braided shield 2.9dB/100ft. 4.5dB/100ft. 4.6dB/100ft. 4.9dB/100ft.
RFS LCF12-50J 1/2-inch solid shield 3.5dB/100ft. 5.5dB/100ft. 5.6dB/100ft. 5.9dB/100f
t
.
RFS LCF12-58J 5/8-inch solid shield 2.8dB/100ft. 4.4dB/100ft. 4.5dB/100ft. 4.8dB/100ft.
There are several other brands and models of transmission line that are perfectly
acceptable. However, for extremely long transmission lines and/or extremely long radio
paths, it may be necessary to use waveguide transmission line instead of coaxial
transmission line. In these cases, waveguide type EW20 is recommended for EX-2.4i
models (0.45dB/100ft. loss at 2.4GHz), and type EW52 for the EX-4.9i and EX-5i
models (1.2dB/100ft. loss at 5.8GHz, 1.35dB/100ft. loss at 5.3GHz).
It is critical that the transmission line and antenna be capable of supporting the same type
of connector, or easily adapted. It can be important to minimize the number of connectors
and adapters, and it is ideal that they match directly without adaptation. In most cases,
transmission line allows for N-type male connectors and antennas have N-type female
connectors. For waveguide, the waveguide flange can typically accommodate a direct
adapter to an N connector, or alternatively, the antenna can be purchased with a direct
waveguide connection. But often a flexible coaxial jumper is required to connect between
the waveguide and antenna, as waveguide is generally inflexible and can be mechanically
challenging to align to the exact antenna connector location.
If possible, connect the primary transmission line directly to the antenna. It is desired to
have the fewest possible pieces of transmission line in the system, to minimize losses and
points of failure from connectors. The antenna can typically accommodate a direct
connection if planned in advance. Use a 90ºadapter for the connection to the antenna, if
necessary, but confirm that all connectors and transmission lines are properly specified
for the operating frequency with minimum loss, proper impedance (50 Ohm) and proper
VSWR characteristics.
Transmission line connector termination is a critical element of the installation. Many
‘factory built’ RF transmission lines do not provide the proper characteristics for proper