User's Manual

RF Exposure Limits
2.3 Example Compliance Boundary Determination
The following example of a compliance boundary for the general public is for an
antenna operating in the 2100 MHz frequency band. The antenna has a length
of 1 meter, an antenna gain of 18 dBi, which corresponds to a numerical gain of
63, a half-power beam width of 60 degrees, and a maximum output power of
40 dBm, which corresponds to 10 W.
dBi: 10·log
10
([numerical antenna gain]) = [antenna gain in dBi]
dBm: 10·log
10
([power in mW]) = [power in dBm]
The ICNIRP power density reference level for general public exposure at
2100 MHz is 10 W/m
2
.
The compliance distance in front of the antenna is calculated using both the
far-field formula (equation 4) and the near-field formula (equation 5).
Far-field formula:
Near-field formula:
The most accurate estimation of the compliance distance for general public
exposure in front of the antenna is 1.9 meters in this example.
The cylindrical compliance boundary is estimated using the general rule
described in Section 2.2 on page 5. The compliance distance behind, above,
and below the antenna is about 1/20th of the distance in front of the antenna.
The diameter of the cylindrical compliance boundary is calculated as the depth
of the antenna plus the compliance distance behind and in front of it. Assuming
an antenna depth of 10 cm, the diameter of the compliance boundary in this
case is 2.1 meters. The height of the cylindrical compliance boundary is
calculated as the distance above and below the antenna plus the height of
the antenna. The height of the compliance boundary in this case is therefore
1.2 meters.
It is recommended always to round the calculated compliance boundary
dimensions upwards.
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124 46-EN/LZT 720 0399 Uen E 2008-09-29