Construction Materials - Black Box LW0050A Manual

sufficient to ensure good performance levels. However, in cases where multipath
propagation exists, we recommend 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 few milliseconds).
Multipath propagation is to be expected when there are potential reflectors
between the main and remote sites. 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.
When installing a single antenna, modify the transmit diversity option to either
antenna 1 or antenna 2, according to the antenna being used (refer to
Section 3.4.3).
Antenna Polarization
Antenna polarization must be the same at either end of the link. In most
applications, the preferred orientation is vertical polarization. Above-ground
propagation of the signal is better when it is polarized vertically. To verify antenna
polarization, refer to the assembly instructions supplied with the antenna set.
5.2.3 C
ONSTRUCTION
A cell's coverage area is affected by the construction materials of the walls,
partitions, ceilings, floors, and furnishings of the cell. These materials may cause
radio signal loss:
• Metal objects reflect radio signals. They do not let the signals pass through.
• Wood, glass, plastic, and brick reflect part of the radio signals and allow part of
the radio signals to pass through.
• Water and objects with a high moisture content absorb a large part of the
radio signals.
CHAPTER 5: Planning and Installing Wireless LANs
M
ATERIALS
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