User Manual

RF-Orchestra!™ Transmitter Installation and Operation Human Exposure Compliance
July 2000 6880493G02-C xxiii
adjusted. The following example sets forth the distances from the antenna to which access
should be prevented in order to comply with the uncontrolled and controlled environment
exposure limits as set forth in the ANSI IEEE standards and computed above.
Calculations for RF-O! 900-MHz Paging Station
Calculating the minimum distance from the antenna necessary to meet the requirements of an
uncontrolled environment, we assume the following:
• Transmit frequency = 930 MHz
• Base station cabinet output power, P = +56.02 dBm (400 Watts)
• Antenna feeder cable loss, CL = 2.0 dB
• Antenna input power Pin = P - CL = +56.02 - 2.0 = +54.02 dBm (252.35 Watts)
• Antenna gain, G = 9.0 dBd [11.15 dBi (13.03)] Antenna height, h = 3 m
Using the following relationship (cylindrical model used for near field calculation):
where W is the maximum permissible power density in W/m
2
and r is the safe distance
from the antenna in meters. The desired distance can be calculated as follows:
Note: r = 0.43m for Controlled Environment
where W = 6.2 W/m
2
was obtained from table above and converting from mW/cm
2
to
W/m
2
.
Note: The above result applies only in the direction of maximum radiation of the antenna. Actual
installations may employ antennas that have defined radiation patterns and gains that differ
from the example set forth above. The distances calculated can vary depending on the actual
antenna pattern and gain.
Pin
W =
_____
2 π h
Pin 252.35
r = _______ = ________ = 2.16
2 π h W 2 π
.
3
.
6.2