## Free space propagation loss in low power radio frequency bands

What is propagation loss?

This graph shows free space propagation loss compared with operating range in the frequencies used for SRD (short range devices) in Europe. This is only theoretical data and it may differ from the data obtained in actual applications due to the environment or operating conditions. However greater loss at higher frequencies can be seen clearly.

## Calculation of free space basic propagation loss

< Click to move to the calculation window >

< Formula >

## Calculation of propagation loss over flat terrain

< Click to move to the calculation window >

* The blue line is free space basic propagation loss
* The purple line is propagation loss over flat terrain.

< Formula >

*γ: Ground return coefficient, Δl: Difference in propagation distance of direct waves and reflected waves.