WaveRider LMS4000, User Manual

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3 Detailed Description
APCD-LM043-4.0 21
The WaveRider diversity antenna contains two vertical antenna elements mounted inside and
on either side of the antenna housing. The phasing between these elements, which modifies
the antenna pattern, is controlled by a DC voltage from the EUM. It produces two patterns, one
perpendicular to the face of the antenna, which has a gain of about 6 dBi, and the other, a
dual-beam pattern off both sides, offering about 3 dBi gain for each beam. These beam
patterns are illustrated in
Figure 13 .
Figure 13 WaveRider Switched-beam Diversity Antenna — Beam Patterns
The EUM samples the signal strength from both antenna patterns during the preamble of
every received packet and automatically selects the best signal. When the EUM transmits, it
sends on the antenna pattern that was last used to receive a signal. Since most of the traffic
comes from the CCU, the EUM samples the signal strength often—typically faster than once
every 5 ms.
The end user must position the switched-beam diversity antenna correctly to receive an
adequate signal level. The Radio LED on the EUM, described in
Indicators and Connectors on
page 74, can be used to help with the alignment. Since the switched-beam diversity antenna
has a good front-to-back ratio, it can be positioned to suppress interference from other
wireless devices at the end-user’s premises.
WaveRider also offers a simple dipole antenna, which can often be used where the path to the
CCU is very short or relatively unobstructed; i.e., where there is a short line of sight path from
the EUM to the CCU with no more than a wall or window obstructing the path.
Other WaveRider-approved antennas can be used at EUM locations that require outdoor
antennas. A professional installer is required to install outdoor EUM antennas to ensure the
antenna system is properly installed with lightning protection and consistent with FCC and
Industry Canada guidelines, which are outlined in
Appendix D on page 185 .
Transmission Line
If the WaveRider diversity or dipole antenna is used, it comes equipped with RF cables and
connectors. The connector is a proprietary WaveRider connector, which is mandated by the
FCC requirement that the connectors used in ISM band products that are not professionally
installed must be unique, or at least not readily available. If an alternate indoor or outdoor
antenna is used, the installer must obtain an RF jumper cable to connect the antenna cable to
the EUM. These jumper cables can be obtained from WaveRider.
Beam Pattern A
Beam Pattern B