Line of Sight Calculation

Egli calculations are used to mathematically calculate propagation loss. The value tells how much the signal strength is decreased due to the distance between the transmitter and the receiver. For this we use the Egli model. The Egli model is a simplified model that assumes “gently rolling terrain with average hill heights of approximately 50 feet (15 meters)” (Land Mobile Radio Systems, Edward N. Singer, PTR Prentice Hall, 1994, p. 196). Because of this assumption, no terrain elevation data between the transmitter and receiver facilities is needed. Instead, the free-space propagation loss is adjusted for the height of the transmitter and receiver antennas above ground.

As with many other propagation models, Egli is based on measured propagation paths and then reduced to mathematical model. In the case of Egli, the model consists of a single equation for the propagation loss.

Variable factors to consider when using Egli Calculations:

The distance between two sites
The (possible) height of the antennas
The transmit power of the data radio
The receiver sensitivity of the data radio
The antenna gain
Attenuation = 117 + 40 x log(D) + 20 x log(F) – 20 x log (Ht x Hr)

Enter the values to calculate your propagation loss, or alternatively, enter an acceptable propagation loss, and the maximum transmission distance will be calculated.