Setup Manual

Connecting External Antennas to the BSU and SU
Standard Tsunami Multipoint outdoor unit
models include integral antennas. However, SU
models 40100-xxxC and BSU models 40400-xxC
replace the integral antennas with a type-N
female connector, letting you purchase and use
antennas better suited for your particular
application, if so desired.
Planning for Antenna Installation
In general, the larger the antenna used with the
radio, the better the link performs. Larger
antennas have narrower beamwidth and higher
gain, which yield better link performance (higher
fade margin, better availability) and improve
immunity to interference. However, larger
antennas are more costly to purchase and install
than smaller antennas and, in some cases,
require special installation equipment and more
robust mounting structures (due to increased
weight and wind loading).
Base stations, however, require wide
beamwidths in azimuth so that a large segment
of subscribers can be accessed spatially.
Antennas are available to allow sectors ranging
from 30° to 360°. Of course, the larger the
sector, the less antenna gain for longer
transmission distance and interference
immunity.
Finally, antenna polarization must be considered.
The BSU and SU integral antennas use left-hand
circular polarization (LHCP). External antennas
with either linear or circular polarization can be
considered. Use the following guidelines to
assist in your planning.
1. The polarization of the BSU and SU antennas
should be of the same type. For a given
polarization, the same polarity (vertical ir
horizontal) must be used at each end of the
link.
2. Linear and circular polarization can be used
at opposite ends of the link; however, this
results in a 3 dB loss in signal strength.
3. Integral antenna units and external antenna
units can be used in the same sector.
4. Only LHCP antennas can be used with SUs
connecting to a BSU with Active Interference
Rejection (A.I.R.).
Note: The A.I.R. BSU is compatible only with LHCP
signals from SUs. SUs must use LHCP
antennas; either the integral antenna or an
LHCP external antenna.
You should consider all of these factors when
selecting an antenna. This advanced planning
also yields the transmission line requirements.
4 Connecting External Antennas to the BSU and SU
Draft Date: 02/25/03 CPN 000000