KNS Ku-BAND RX, Инструкция по установке и эксплуатации

Страница: 11 / 123

3
For the purpose of applying these definitions, awareness of the potential for RF
exposure in a workplace or similar environment can be provided through specific training
as part of an RF safety program. Warning signs and labels can also be used to establish
such awareness as long as they provide information, in a prominent manner, on the risk of
potential exposure and instructions on the methods of minimizing such a risk of exposure.”
The following conclusions can be drawn from these tables (Figure 2-1):
Power density between the feed flange and reflector is at a hazardous level and access
to this area must be prevented while the terminal is transmitting. Under no
circumstances should any part of a person’s body be placed in this region while the
terminal is transmitting.
Based on a controlled-area power density of 5 mW/cm
2
over any 6-minute period, in
some cases less than 14.6 seconds of exposure is allowable in this region. Note that, in
general, an operator would not be manually adjusting the feed during a high-rate, high-
power transmission. Also note that the power density decreases toward the reflector (as
the beam widens from the feed), so the maximum exposure time increases as the
distance from the feed increases.
Near-field levels of radiation are below the controlled-area requirement, but in some
cases are above the uncontrolled area requirement. Although the nature of
transmissions is such that radiated power levels should not reach full power at any time,
there is no absolute guarantee of reduced transmission levels; therefore, access to the
near field of the antenna must also be restricted. Since the near field is contained within
a cylinder pointed from the reflector toward the satellite, we can compute the horizontal
distance from the front of the reflector to which access must be restricted. Table 2-1
computes this distance. At distances in excess of the tabulated limits, access can be
unrestricted. Between the antenna and the tabulated limits, access should be limited to
less than 10 minutes in any 30-minute interval.
Far-field levels of radiation are below the uncontrolled-area requirement and are
therefore not a concern.