Electromagnetic radiation is considered to be produced when charged particles are accelerated by force acting on them. EMR carries energy which is called radiant energy passing through space continuously away from the source. Exact measurements can not possible because of considering the complexity of the environment. The complexity may cause reflection, deflection, and scattering of electromagnetic fields.

An approximation can be made with the following equation:
S = (P(W) x G_numeric)/(4 x r?(m) x π)
Where,
P = Maximum output power at antenna port of the BTS in W

r = Distance between the antenna and the point of exposure in meters

G_numeric= Numeric gain, where

G_numeric = 10^GdB/10

GdB = G_antenna(dB) – B_cable(dB) – B_{vertical-attenuation}(dB) – B_{horizontal-attenuation}(dB)
B = attenuation in dB 
N.B. The maximum output power of a Microwave equipment is usually limited by license conditions of the network operator.