User's Manual

Basic Installation
SU-I/ID Installation Manual 4 BreezeACCESS MMDS Series
• For most applications, the most convenient choice is to use SU-I units,
equipped with two integral 2dBi omni antennas.
2.4.2 Location of the Antenna(s)
• Any physical object in the path between two units can cause signal
attenuation. Common obstructions are buildings and trees. If a unit’s
antenna is installed indoors, the walls and/or windows between the two
sites are physical obstructions. If the antenna is positioned outdoors, any
buildings or other physical structure such as trees, mountains or other
natural geographic features higher than the antenna and situated in the path
between the two sites can constitute obstructions.
• Install indoor antennas as close as possible to a window (or wall if a
window is not accessible) facing the required direction. Avoid metal
obstacles such as metal window frames or metal film anti-glare windows in
the transmission path. Install outdoor antennas high enough to avoid any
obstacles, which may block the signal.
• Position the antennas clear of metal furniture and away from moving metal
objects such as metal fans or doors.
• For best performance, position the antennas clear of radiation sources that
emit in the 2.5 - 2.7 GHz frequency band, such as microwave ovens.
2.4.3 Antenna Diversity
In applications where no multipath propagation is expected, a single antenna is
sufficient to ensure good performance levels. However, in cases where multipath
propagation exists, BreezeCOM recommends that two antennas be used. This
takes advantage of space diversity capabilities. By using two antennas per unit,
the system can select the best antenna on a per-packet basis (every several
milliseconds).
Multipath propagation is to be expected when there are potential reflectors
between the Access Unit and Subscriber Units. These reflectors may be buildings
or moving objects such as airplanes and motor vehicles. If this is the case, the
radio signal does not travel in a straight line, but is reflected or deflected off of
the object, creating multiple propagation paths.