User's Manual

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WARNING!
RF RADIATION EXPOSURE HAZARD
This warning is provided by Broadcast Microwave Services (BMS) Inc. for safety purpose. The
following information help to reduce the risk of RF exposure hazard.
FCC Limit of RF Exposure
According to Federal Communication Commission (FCC), the Maximum Permissible Exposure (MPE) for
FR radiation has been set to 1.0 mW/cm
2
for the Truck-Coder II equipment (OET Bulletin 65).
Truck-Coder II is a non-broadcast transmitter and without an antenna it will not create RF exposure (power
density) exceeding the 1.0 W/cm
2
FCC limit.
However a high-gain antenna such as a parabolic dish will greatly enhance the Truck-Coder II output
power density beyond the MPE limit of 1.0 mW/cm
2
.
In this situation a minimum distance from the antenna needs to be calculated in order to keep the MPE
always below the safety limit. The calculation has been done for Truck-Coder II based on the formula
mentioned in OET Bulletin 56.
The calculations have been done for different commonly used antenna in Electronic New Gathering (ENG)
systems.
Digital Transmission
Figure 1 shows the plot of the minimum exposure distance for 0dBi, 5dBi, 16dBi, and 30dBi antennas. The
Truck-Coder II transmitter has been in digital mode with an average power of 5 Watts typical. The
minimum exposure distances are found from the cross points of the exposure graphs (for various antennas)
with the line of maximum permissible exposure (i.e. 1 W/cm
2
). Notice that the numbers in Figure 1 predict
the worse case scenario, which is straight in front of the antenna (exposing to the antenna main-lobe).
Obviously the side-lobe exposures are well below these numbers as the radiation intensity dramatically
reduces on the side lobes.