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.
* 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.
*Reference: Radio waves propagation
handbook REALIZE INC.
Free space propagation loss in low power radio frequency bands
