User's Manual

10 LEDR Series I/O Guide MDS 05-3627A01, Rev. D
Keep the following points in mind when setting up your point-to-point
system:
1. Systems installed in lightly populated areas are least likely to
encounter interference; those in urban and suburban environments
are more likely to be affected by other devices operating in the
radio’s frequency band and adjacent services.
2. Directional antennas must be used at each end of a point-to-point
link. They confine the transmission and reception pattern to a com-
paratively narrow beam, which minimizes interference to and from
stations located outside the pattern. The larger the antenna, the more
focused the transmission and reception pattern and the higher the
gain.
3. If interference is suspected from another system, it may be helpful
to use antenna polarization that is opposite to the interfering sys-
tem’s antennas. An additional 20 dB (or more) of attenuation to
interference can be achieved by using opposite antenna polarization.
Refer to the antenna manufacturer’s instructions for details on
changing polarization.
3.3 Antenna and Feedline Selection
Antennas
The antenna system is perhaps the most crucial part of the system
design. An antenna system that uses poor quality feedline, or is improp-
erly aligned with the companion site, will result in poor performance, or
no communication at all.
A directional antenna must be used for point-to-point systems to mini-
mize interference both to and from nearby systems. In general, cylin-
drical or dish type antennas with a parabolic reflector must be used. Yagi
or corner reflector types may be acceptable in some applications. Check
government regulations for your region.
The exact style of antenna used depends on the size and layout of a
system. In most cases, a directional “dish” type of antenna is used with
the radio (Figure 7). Dish antennas maximize transmission efficiency
and restrict the radiation pattern to the desired transmission path.