4RF Aprisa XE, Руководство пользователя

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Preparation | 22
Coaxial feeder cables
To ensure maximum performance, it is recommended that you use good quality low-loss coaxial cable
for all feeder runs. For installations requiring long antenna cable runs, use Andrew Heliax™ or
equivalent.
When using large diameter feeders, use a short flexible jumper cable between the feeder and the
terminal to reduce stress on the antenna port connector.
All coaxial cable has loss, that is, the RF energy traveling through it is attenuated. Generally speaking,
the larger the diameter of the cable, the less the loss. When selecting a coaxial cable consider the
following:
Factor Effect
Attenuation Short cables and larger diameter cables have less attenuation
Cost Smaller diameter cables are cheaper
Ease of installation Easier with smaller diameter cables or short cables
When running cables:
ƒ
Run coaxial cable from the installation to the antenna, ensuring you leave enough extra cable at
each end to allow drip loops to be formed.
ƒ For 19-inch rack mount installations, cables may be run from the front of the rack directly onto the
antenna port. They may also be run through the back of the rack to the front.
ƒ Terminate and earth or ground the cables in accordance with the manufacturers' instructions.
Bond the outer conductor of the coaxial feeder cables to the base of the tower mast.
Link budget
All of the above factors (and many others not mentioned) combine in any proposed installation to
create a link budget. The link budget predicts how well the radio link will perform after it is installed.
Use the outputs of the link budget during commissioning testing to confirm the link has been installed
correctly, and that it will provide reliable service.