User's Manual

8A535X01 Rev. Preliminary Page 7 of 17
Antenna Gain dBi 0 2.15 5.15 8.15 11.15 14.15 17.15
dBd -2.15 0 3 6 9 12 15
Antenna RF Powe
r
1 W 18 23 33 46 64 91 128
5 W 40 51 72 102 144 203 286
10 W 57 72 102 144 203 286 404
15 W 69 88 125 176 248 351 495
20 W 80 102 144 203 287 405 571
25 W 89 114 161 227 320 452 639
30 W 98 125 176 249 351 496 700
37.3 W 109 139 196 277 391 552 780
TABLE 1 OCR UHF MPE Safe Distances in cm for Various Antenna Gains
If the antenna gain is not listed in Table 1, 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