User's Manual

8A535X01 Rev. Preliminary-02 Page 9 of 19
20 W 52 67 94 132 187 264 372
25 W 58 74 105 148 209 295 416
30 W 64 81 115 162 229 323 456
37.3 W 71 91 128 181 255 360 508
TABLE 3 OCR 900 MPE Safe Distances in cm for Various Antenna Gains
If the antenna gain is not listed in Table 1, Table 2 and Table 3, the MPE Safe Distance is calculated
as follows:
Calculation Method for RF Safety Distance r:
S = PG/4Πr
2
=EIRP/4Πr
2
Where: P: power input to the antenna in mW.
EIRP: Equivalent (effective) isotropic radiated power in mW.
S: power density mW/cm
2
.
G: numeric gain of antenna relative to isotropic radiator.
r: distance to centre of radiation in cm.
RF EXPOSURE DISTANCE LIMIT: r = (PG/4ΠS)
1/2
= (EIRP/4ΠS)
1/2
For General Population/ Uncontrolled Exposure:
S = 0.2
mW/cm
2
for frequency range of 30MHz – 300MHz.
S = f/1500 in
mW/cm
2
for frequency range of 300MHz – 1500MHz. f is the minimum used
frequency in MHz.
As an example, let us consider a case of minimum frequency f = 380MHz, RF power P = 37.3W and
an antenna with gain of 2.15dBi:
P = 37300 mW = 10 log(37300) dBm = 45.717 dBm
EIRP = P + G in dBm = 45.717 dBm + 2.15dB = 47.867 dBm = 10
(47.867/10)
= 61194mW
S = 380/1500
mW/cm
2
For General Population/bystanders: r = (EIRP/4ПS)
1/2
= (61194/4П(380/1500))
1/2
= 138.64cm.
The MPE safe distance is therefore at least 139cm (54.73”).
ATTENTION!