User's Manual

42 UltraWAVE BTS Installation and Commissioning Guide, Release 6.5A
RF power density can be calculated with the equation: S = P * G / 4p R2, where S = power density in
mW/cm, P = power input to the antenna in mW, G = power gain of the antenna, and R = distance to the
center of radiation of the antenna in cm. By rearranging this equation, the relationship between distance
(R) and Power Density (S) can be found.
Rearranging R =Ö(PG / 4p S), and solving for the maximum limits of 2.90 mW/ cm 2, and 0.58
mW/ cm 2 we have:
R(2.90 mW/cm2) = Ö 1,260,000 mW / 4p * 2.90 = 186 cm, or 73 inches.
R(0.58 mW/cm2) = Ö 1,260,000 mW / 4p * 0.58 = 416 cm, or 164 inches.
These results show that the general population RF exposure limits are not exceeded as long as the
general population is kept 164-inches from the feed point of the antenna.
The propagation characteristics at 870 MHz dictate a line-of-sight type of RF path. As such, typical
installation locations are up on rooftops or masts to get above ground level path obstructions. When the
Ultrawave antennas are installed in this manner, the general population will be further than 164-inches
from the antenna, and RF exposure limits will be met.
1,26,000 mW is used to account for two 50,000 mW transmitters
operating into each 120 degree sector.