The U.S. FCC has laws that limit the use of amplifiers with a WLAN. An
amplifier may only be used, if it is sold as part of a system. This means that
the AP, amplifier, extension cable, and antenna are all sold as a system. These
laws help to ensure that amplifiers are tested with certain products and
legally marketed and sold.
Outdoors
The U.S. FCC ruling is
designed to keep installers from adding an amplifier and interfering with other
wireless spectrum users. Interference from improperly configured equipment is a
big concern in a metropolitan area. Be aware of the local laws and of other
systems in the area, which may be affected by an amplifier.
Figure
illustrates an
example of an outdoor, waterproof, bidirectional pole mounted amplifier for use
with 2.4 GHz Spread Spectrum radios and WLAN equipment. The device has a low
noise receiver pre-amplifier and a transmit-power amplifier.
Indoors
When installing equipment indoors, it is preferred to
install an additional access point rather than installing an amplifier. In rare
instances, an amplifier may be needed indoors. Care must be taken to avoid
interfering with nearby wireless spectrum users. Some amplifiers sold today are
certified with entire product lines, which include all APs, cables, and
antennas. Figure
shows a
bidirectional, indoor amplifier for use with 2.4 GHz Spread Spectrum radio
modem and WLAN equipment. Like the outdoor amplifier, it has a low-noise
receiver pre-amplifier and transmit-power amplifier.