Exalt Communications, Inc.
r-series
Installation and Management Manual
5000007 (ETSI)
30
2007-02-12 (draft)
(generally) of the far end radio, and then slightly tighten the azimuth and elevation adjustments
so that the antenna maintains its general position and is safe to be left without additional
securing. Refer to the Exalt white paper,
Antenna Alignment
, for more information on antenna
alignment techniques.
Transmission Line from Antenna to Radio r-(x)c Series models only
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 6 lists representative samples of transmission line types recommended for the Exalt Digital
Microwave Radio.
Table 6
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/100ft.
5.7dB/100' 6.0dB/100'
Andrew LDF4.5-50
5/8-inch
solid
shield
4.3dB/100ft.
4.4dB/100' 4.7dB/100'
Times LMR-600
1/2-inch
braided
shield
6.8dB/100ft.
6.9dB/100' 7.3dB/100'
Times LMR-900
5/8-inch
braided
shield
4.5dB/100ft.
4.6dB/100' 4.9dB/100'
RFS LCF12-50J
1/2-inch
solid
shield
5.5dB/100ft.
5.6dB/100' 5.9dB/100'
RFS LCF12-58J
5/8-inch
solid
shield
4.4dB/100ft.
4.5dB/100' 4.8dB/100'
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