The type of cable shown in Figure
that connects
antennas to WLAN devices is a possible source of radio communication
difficulties.
Cable selection is also important. When setting up bridges
to communicate over a long distance, the antenna cables should not be longer
than necessary. This is important because the longer a cable is, the more its
signal will be attenuated, resulting in lower signal strength and consequently
lower range. A Cisco bridge range calculation utility can be used to calculate
the maximum distance that two bridges can communicate over based on the antenna
and cable combinations in use.
Like any other network cables, the
antenna cables must be properly installed to ensure that the signal they carry
is clean and free from interference. To ensure that cables perform to their
specifications, it is important to avoid the following:
-
Loose connections – Loose connectors on either end of the cable
result in poor electrical contact and degrade the signal quality.
-
Damaged cables – Antenna cables with obvious physical damage do not
perform to specification. For example, damage can result in induced reflection
of the signal within the cable.
-
Cable runs shared with power cables – It is possible for EMI
produced by power cables to affect the signal on the antenna cable.
-
Water in cable connections – It is possible for water to penetrate
connectors that are not properly sealed. This will cause severe degradation to
the RF signal.
For advanced troubleshooting a cable analyzer can be used to isolate
problems.
