Estimation Of Exposure To Electromagnetic Fields; Calculation Of Safe Distance - Huawei Airbridge BTS3612A-1900 Technical Manual

Technical Manual
Airbridge BTS3612A CDMA Base Station
Power density S [mW/cm
f [ MHz
=
S
300
Power density S [mW/cm
f [ MHz
=
S
1500
D.3 Estimation of Exposure to Electromagnetic Fields
The following method describes a theoretical approach to calculate possible exposure
to electromagnetic radiation around a BTS antenna.
Precise statements are basically only possible either with measurements or complex
calculations considering the complexity of the environment (e.g. soil conditions, near
buildings and other obstacles) which causes reflections, scattering of electromagnetic
fields.
The maximum output power (given in EIRP) of a BTS is usually limited by license
conditions of the network operator.
A rough estimation of the expected exposure in power flux density on a given point can
be made with the following equation. The calcualtions are based on FCC OET 65
Appendix B.
P (
=
S
4
Whereas:
P = Maximum output power in W of the site
G = Numeric gain of the antenna relative to isotropic antenna
numeric
R = distance between the antenna and the point of exposure in meters
D.4 Calculation of Safe Distance
Calculation of safe distane can be made on a site by site basis to ensure the power
density is below the specified limitse. Or guidelines can be done beforehand to ensure
the minimum distances from the antenna is maintained through the site planning.
2
] for controlled area at 880 MHz
] 880
= =
2 9 . mW / cm
300
2
] for uncontrolled area at 880 MHz
] 880
= =
. 0 58 mW /
1500
∗
W ) G
numeric
π ∗
∗
2
r ( m )
Appendix D Electromagnetic Radiation
2
2
cm
D-3
System Principle