Exalt Installation and Management Guide
EX-r Series GigE Digital Microwave Radios
29
201872-003
2015-10-23
Transmission Line from Antenna to Radio (EX-4.5r-c GigE and
EX-5r-c GigE)
Most installations use a very short length of coaxial transmission line for the connection between the
antenna and the radio device. Coaxial transmission line can either have a solid or braided shield. Solid-
shield cables are more resistant to external signal coupling and interference, but are generally stiffer
than braided cables. Consult the path or site engineer(s) to ensure that the proper materials are chosen
for the installation and that all factors were considered.
Generally, the larger the diameter of the transmission line, the lower the loss. So for longer runs of
transmission line, larger diameter cables are highly advised. However, at 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.
Table 4 lists representative samples of transmission line types recommended for the Exalt Digital
Microwave Radio.
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.
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
90º adapter 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 transmission, despite their
published specifications, often due to the fully or semi-automated process of factory termination,
which may not have considered the frequency of your system. When buying pre-terminated
transmission line, it is strongly advised to obtain the documentation of test measurements on the
connected transmission line showing that the loss characteristics and VSWR are within the specified
limits specifically at your operating frequency. In addition to factory-built transmission line, self-
terminated transmission line can suffer the same issues.
Table 4 Recommended transmission line
Manufacturer
Type
Description
Loss at 5.3GHz
Loss at 5.8GHz
Andrew
LDF4-50
1/2-inch solid shield
5.7dB/100'
6.0dB/100'
Andrew
LDF4.5-50
5/8-inch solid shield
4.4dB/100'
4.7dB/100'
Times
LMR-600
1/2-inch braided shield
6.9dB/100'
7.3dB/100'
Times
LMR-900
5/8-inch braided shield
4.6dB/100'
4.9dB/100'
RFS
LCF12-50J
1/2-inch solid shield
5.6dB/100'
5.9dB/100'
RFS
LCF12-58J
5/8-inch solid shield
4.5dB/100'
4.8dB/100'
