Earth Station Antennas
earth stations consist of large parabolic dish-like antennas
that are used to transmit or receive microwave signals via
satellites in orbit around the earth. The satellites receive
the signals beamed up to them and, in turn, retransmit the
signal back down to an earthbound receiving station. These
signals allow a variety of communication services to be performed,
including long distance telephone services and cable TV programming.
Since earth station antennas are directed toward satellites
above the earth, the transmitted beams point skyward at various
angles of inclination, depending on the particular satellite
being used. Because of the longer distances involved, the
power levels used to transmit these signals are relatively
great when compared to those used for microwave point-to-point
communications. However, as with microwave point-to-point
antennas, the diameter of the beam used to transmit the radiation
is narrow and highly directional. Therefore, it is unlikely
that a member of the public would access the main beam.
emission of radiation from satellite earth station antennas
is regulated in New Jersey by N.J.A.C.
7:28-42, Radio Frequency Radiation. Radiation levels
on the ground will vary, depending upon the angle of inclination
of the antenna, the antenna pattern itself and the intensity
of the transmitted signal. However, under "worse case
conditions", the radiation levels encountered by a member
of the general public are still likely to be 100 times lower
than the regulatory limits specified in Subchapter 42. Based
on current research findings, it is not expected that any
adverse health effects would result from exposure to radiation
levels this low. Conversely, a worker who needs to gain access
to one of these antennas can easily be exposed to hazardous
radiofrequency radiation levels if proper precautions are
all earth station antennas transmit signals. Some antennas
are only used to receive information and therefore, do not
pose any health hazard. Included in this group would be the
type of satellite dish that can be purchased by the general
public for the purpose of viewing television programs.
Subchapter 42 only regulates stationary sources, (see N.J.A.C.
7:28-41.1(a)), mobile satellite earth station antennas such
as those used in the remote broadcasting of television programs
are not regulated by this Program.
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