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Section 4: Safety Guidelines and Warranty Information
114 4A: Safety
of each transmitter. Typically, 21 channels per antenna sector are
available. For a typical cell site using sector antennas, each of the three
transmitting antennas could be connected to up to 21 transmitters for a
total of 63 transmitters. However, it is unlikely that all of the transmitters
would be transmitting at the same time. When omni-directional
antennas are used, a cellular base station could theoretically use up to 96
transmitters, but this would be very unusual, and, once again, it is
unlikely that all transmitters would be in operation simultaneously. Base
stations used for PCS communications generally require fewer
transmitters than those used for cellular radio transmissions, since PCS
carriers usually have a higher density of base station antenna sites.
11. Are wireless telephone base stations safe?
The electromagnetic RF signals transmitted from base station antennas
stations travel toward the horizon in relatively narrow paths. For
example, the radiation pattern for an antenna array mounted on a tower
can be likened to a thin pancake centered around the antenna system.
The individual pattern for a single array of sector antennas is wedge-
shaped, like a piece of pie. As with all forms of electromagnetic energy,
the power decreases rapidly as one moves away from the antenna.
Therefore, RF exposure on the ground is much less than exposure very
close to the antenna and in the path of the transmitted radio signal. In
fact, ground-level exposure from such antennas is typically thousands of
times less than the exposure levels recommended as safe by expert
organizations. So exposure to nearby residents would be well within
safety margins.
Cellular and PCS base stations in the United States are required to
comply with limits for exposure recommended by expert organizations
and endorsed by government agencies responsible for health and safety.
Measurements made near cellular and PCS base station antennas
mounted on towers have confirmed that ground-level exposures are
typically thousands of times less than the exposure limits adopted by the
FCC. In fact, in order to be exposed to levels at or near the FCC limits for
cellular or PCS frequencies an individual would essentially have to
remain in the main transmitted radio signal (at the height of the
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