User's Manual

Copyright © Chung Nam Electronics. All Rights Reserved.
8
Radio Frequency Radiation Exposure Evaluation:
The highest RF output power of the EUT was measured at 27.0dBm at 902.75MHz
and 927.25MHz. According to §1.1310 of the FCC rules, the power density limit for
General Population/Uncontrolled Exposure at 902.75MHz (worst case) is f
(MHz)
/1500
= 0.6018mW/cm
2
. The maximum permissible exposure (MPE) is calculated to show
the required separation distance that must be maintained during installation to
maintain compliance with the power density limit.
The following formula was used to calculate the Power Density:
2
4 R
PG
S
π
=
where:
S = Power Density
P = Power input to the antenna
(Output power from the EUT antenna port
(dBm)
)
G = Gain of Transmit Antenna (linear gain)
R = Distance from Transmitting Antenna
For the EUT, the calculation is as follows:
P = 27.0dBm = 500mW (Output power from the EUT antenna port)
G = Antenna Gain = 4.5dBi = anti-log(4.5/10) = 2.818
At 20cm separation,
2
)20(4
818.2500
π
×
=S
=0.2803mW/cm
2
Based on the above calculation for 20cm separation, the power density does not
exceed FCC limit of 0.6018mW/cm
2
.