Technical

Wave propagation calculation tool (for free-space and 2 wave model)

By inputting parameters for frequency, transmit power and distance, it is possible to calculate the wave propagation characteristics for free-space and 2-wave model.

Basic input parameters

❶ Input the radio frequency in MHz

Frequency  MHz

❷ Input the radio transmission power in dBm

Transmission power  dBm --> 

❸ Input the propagation distance in meters

Distance  m

Advanced input parameters

❹ Antenna height

At transmitter  m

At receiver  m

❺ Antenna gain

At transmitter  dBi

At receiver  dBi

 Log / linear

Explanation of the free-space and 2-wave model

Free-space

Propagation in a perfect vacuum without wave reflection. Theoretically, the received power drops off with the square of the distance.

2-wave model

Propagation over an infinitely flat reflective surface. Interference will occur at the receiver when the two waves converge, one having taken a direct route and the other that has been reflected. If they both converge with opposite phase, the overall received power will be less (dead point). The dead points occur more frequently at closer distance to the transmitter. To avoid such areas the receiver will need to be relocated to places where the received power level is at maximum. Using higher frequencies (with shorter wavelengths), the number of dead points will occur more rapidly especially near the transmitter.

In reality, reflections can occur from buildings and mountains creating multipath propagation (delayed wave arrival) so the situation becomes more complex.