User's Guide

Compliance with safety standards Chapter 4: Reference information
4-10
UNDER DEVELOPMENT
phn-2182_003v004 (Oct 2011)
The following calculation is based on the ANSI IEEE C95.1-1991 method, as that provides
a worst case analysis. Details of the assessment to EN50383:2002 can be provided, if
required.
Peak power density in the far field of a radio frequency point source is calculated as
follows:
Where: Is:
S power density in W/m
2
P maximum average transmit power
capability of the radio, in W
G total Tx gain as a factor, converted
from dB
d distance from point source, in m.
Rearranging terms to solve for distance yields:
Calculated distances and power compliance margins
Table 4-13 shows calculated minimum separation distances, recommended distances and
resulting margins for each frequency band and antenna combination. These are
conservative distances that include compliance margins. At these and greater separation
distances, the power density from the RF field is below generally accepted limits for the
general population.
Explanation of terms used in Table 4-13:
Tx burst –
maximum average transmit power in burst (Watt)
P – maximum average transmit power capability of the radio (Watt)
G – total transmit gain as a factor, converted from dB
S – power density (W/m
2
)
d – minimum distance from point source (meters)
R – recommended distances (meters)
2
4
.
d
GP
S
π
=
S
GP
d
.4
.
π
=