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reduce risks. Some products that claim to shield the user from
RF absorption use special phone cases, while others involve
nothing more than a metallic accessory attached to the phone.
Studies have shown that these products generally do not work
as advertised. Unlike "hands-free" kits, these so-called "shields"
may interfere with proper operation of the phone. The phone
may be forced to boost its power to compensate, leading to an
increase in RF absorption. In February 2002, the Federal trade
Commission (FTC) charged two companies that sold devices
that claimed to protect wireless phone users from radiation
with making false and unsubstantiated claims. According to
FTC, these defendants lacked a reasonable basis to substantiate
their claim.
10. What are wireless telephone base stations?
Fixed antennas used for wireless telecommunications are
referred to as cellular base stations, cell stations, PCS ("Personal
Communications Service") stations or telephone transmission
towers. These base stations consist of antennas and electronic
equipment. Because the antennas need to be high in the air,
they are often located on towers, poles, water tanks, or
rooftops. Typical heights for freestanding base station towers
are 50-200 feet.
Some base stations use antennas that look like poles, 10 to 15
feet in length, that are referred to as "omni-directional"
antennas. These types of antennas are usually found in rural
areas. In urban and suburban areas, wireless providers now
more commonly use panel or sector antennas for their base
stations. These antennas consist of rectangular panels, about
1 by 4 feet in dimension. The antennas are usually arranged in
three groups of three antennas each. One antenna in each
group is used to transmit signals to wireless phones, and the
other two antennas in each group are used to receive signals
from wireless phones.
At any base station site, the amount of RF energy produced
depends on the number of radio channels (transmitters) per
antenna and the power 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
Section 4: Safety Guidelines and Warranty Information
4A: Safety 200
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