RF signal attenuation due to rainfall using Crane model

returns the signal attenuation, `L`

= cranerainpl(`range`

,`freq`

,`rainrate`

)`L`

, due to rain based on the
Crane rain model [1]. Signal attenuation is a
function of the signal path length, `range`

, the signal
frequency, `freq`

, and the rain rate,
`rainrate`

. The rain rate is defined as the long-term
statistical rain rate. The attenuation model applies only for frequencies from 1 GHz
to 1000 GHz and is valid for ranges up to 22.5 km. The Crane model accounts for the
cellular nature of rainstorms.

[1] Crane, Robert K.
*Electromagnetic Wave Propagation through Rain*. Wiley,
1996.

[2] Radiocommunication Sector of International Telecommunication
Union. *Recommendation ITU-R P.838-3: Specific attenuation model for rain for
use in prediction methods*. P Series, Radiowave Propagation
2005.

[3] Radiocommunication Sector of
International Telecommunication Union. *Recommendation ITU-R P.530-17:
Propagation data and prediction methods required for the design of terrestrial
line-of-sight systems*. 2017.

[4] Radiocommunication Sector of
International Telecommunication Union. *Recommendation ITU-R P.837-7:
Characteristics of precipitation for propagation modelling*.
6/2017