Today we will discuss a very important relation related to wave propagation. The equation is known as Friis free space equation.

As only a small fraction of radiated power is received at the receiver from an isotropic radiator in free space, but the received signals, must be 10-20 dB above the receiver noise to complete the link between transmitter (T_{X}) and receiver (R_{X}) antenna. The amount of received power depends on transmitted power, gains of transmitter and receiver antennas and separation between them, operating frequency and path attenuation. Thus in order to describe the characteristics of wave propagation, it is necessary to derive equation relating to these parameters. The expression relating these parameters is known as Friis free space wave equation. Continue reading “FRIIS FREE SPACE EQUATION”