User's Manual

Appendix B: Compliance
Page 208 InterReach Fusion Wideband Installation, Operation, and Reference Manual
© 2015 TE Connectivity D-620616-0-20 Rev K • TECP-77-044 Issue 9 • March 2015
HUMAN EXPOSURE TO RF
The U.S. Federal Communications Commission (FCC) has developed guidelines for evaluation of
human exposure to RF emissions. The guidelines incorporate limits for Maximum Permissible
Exposure (MPE) for power density of transmitters operating at frequencies between 300 kHz and
100 GHz. Limits have been set for portable, mobile, and fixed equipment. TE products fall in the
category of fixed equipment; products intended to be permanently secured and exposures are
evaluated for distances greater than 20cm (7 7/8”). Portable devices fall into exposures of less
than 20cm, are SAR evaluations are used.
Antenna gain is restricted to 1.5 W ERP (2.49 W EIRP) in order to
satisfy RF exposure compliance
requirements. If higher than 1.5 W ERP, routine MPE evaluation is needed. The antennas should
be installed to provide at least 20 cm from all persons to satisfy MPE requirements of FCC Part 2,
2.1091.
Basic MPE evaluation is performed by taking the maximum power output of the equipment, the
gain o
f the antenna to be used, and distance from the antenna, referenced in FCC OET Bulletin 65
“Evaluation Compliance with FCC Guidelines for Human Exposure to Radio Frequency for Electric
Fields”.
TE products transmit well below th
e FCC power density limits. FCC defines power output limits
at 20cm distance for various frequency ranges:
• Over 300 MHz to 1.5 GHz the limit is determined by frequency/1500
• Above 1.5 GHz the limit is 1mW/cm2
T
he basic equation for determining power density is:
S = PG / 4πR
2
Where S is power density in mW/cm2
PG, the transmitted power from the a
ntenna identified as EIRP (Equivalent Isotropically Radiated
Power), is the product of power output of device and antenna gain, in mW.
R is the distance
of interest from the antenna.
Typical Installation Example:
Assuming an antenna is placed on a 10 foot ceiling, for a person 6
feet tall, the distance from
antenna to body is 4 feet (112 cm.).
For a PCS 1900 remote unit, the maximum power output, ac
cording to the power table in
“Maximum Output Power P
er Carrier” on page 65, is 16.5 dB.
Assuming a 7 dBi antenna is used, PG in the equation is equal to 23.5 dB (224 mW) EIRP.
Us
ing S = PG/4
πR
2
S = 224/(4x3.14) x (122)
2
= 0.001 mW/cm
2
Also, assuming a minimum distance of 20 cm according to FCC regulations:
S = 224/(4 x 3.14) x (20)
2
= 0.04 mW/cm
2