Exalt Installation and Management Guide
ExtendAir (TDD) Series Digital Microwave Radios
203591-010
29
2012-09-04
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.
The manufacturers of transmission line typically offer instruction and certification for transmission
line termination, and may also provide videos illustrating the process. There is no amount of extra care,
education, precision, and effort that can be overstated for this process.
There is often a need for a small excess of transmission line near the antenna to accommodate both the
need for extra slack as the antenna is loosened and moved for the alignment process, and to
accommodate a drip loop for the transmission line and the initial transmission line securing hardware
and grounding near the antenna. In addition, the transmission line is typically very stiff, and can
provide undue pulling force on the antenna or radio connector. Take care to align the cable with the
connector so that it does not provide any torque or strain on the connector.
Consult your transmission line manufacturer for the proper transportation, hoisting, securing, and
grounding process. Always be very mindful of the entire length of transmission line to ensure that the
transmission line is never twisted, kinked, or over-bent beyond the specified bend radius. Once a
Table 4 Recommended transmission line
Manufacturer
Type
Description
Loss at 4.9GHz
Loss at 5.3GHz
Loss at 5.8GHz
Andrew
LDF4-50
1/2-inch solid shield
5.6dB/100'
5.7dB/100'
6.0dB/100'
Andrew
LDF4.5-50
5/8-inch solid shield
N/A
4.4dB/100'
4.7dB/100'
Times
LMR-600
1/2-inch braided shield
6.8dB/100'
6.9dB/100'
7.3dB/100'
Times
LMR-900
5/8-inch braided shield
N/A
4.6dB/100'
4.9dB/100'
RFS
LCF12-50J
1/2-inch solid shield
5.5dB/100'
5.6dB/100'
5.9dB/100'
RFS
LCF12-58J
5/8-inch solid shield
N/A
4.5dB/100'
4.8dB/100'
Caution:
Always follow the manufacturer’s termination process EXACTLY, and only use the
manufacturer’s authorized tools and connectors for a given transmission line type.
