User guide

Reference RLX-IH ♦ 802.11b
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ProSoft Technology, Inc. Page 79 of 99
April 10, 2007
transmitting antenna polarization is pointed in the vertical direction (vertical
polarization, for short), and the receiving antenna also has vertical polarization,
the maximum amount of power possible will be received. On the other hand, if
the transmit antenna has vertical polarization and the receiving antenna has
horizontal polarization, no power should be received. If the two antennas have
linear polarizations oriented at 45° to each other, half of the possible maximum
power will be received.
6.4.4 Adding Bi-directional Amplifiers
A bi-directional amplifier may be needed if an application requires long lengths of
coaxial cable to reach the antenna. The amplifier is designed to put maximum
transmit power right at the antenna and boost the received signal primarily to
overcome the cable loss. You can only use an amplifier from ProSoft Technology
that is specifically approved for use with the RLX-IH radio, and only in countries
where the amplifier option is approved. See Approved antennas (page 80) for
more information.
The bi-directional amplifier is designed to operate with a coaxial cable loss
between the radio and amplifier of 6.5 dB to 20 dB. The output is always 1/2W,
regardless of the input level. With less than 6.5-dB loss, the amplifier maximum
input rating will be exceeded. With more than 20- dB cable loss, the amplifier will
not turn on.
Refer to Amplifier chart (page 79) to view the minimum and maximum lengths
of various cable types required when you use a bi-directional amp.
Refer to Amplifier Diagram (page 79) for an installation diagram of the amplifier
and its power supply.
Amplifier chart
The following chart lists the minimum and maximum lengths of various cable
types required when you use a bi-directional amplifier.
Cable Type
Cable loss/
100' (dB)
Minimum
length (ft)
Loss (dB)
Maximum
length (ft)
Loss (dB)
LMR195 18.2 36 6.5 109 20
LMR400 6.9 94 6.5 289 20
LMR600 4.4 148 6.5 454 20
LDF4-50A 3.9 167 6.5 512 20
LDF5-50A 2 325 6.5 1000 20
Amplifier diagram
Proper installation of the amplifier and its power supply is shown in the following
diagram. The DC injector can be located by the radio, and the amplifier should be
at the antenna. The bi-directional amplifier is weather proof and can be mounted
outdoors. Refer to the bi-directional amplifier instructions for more information.