Statistics of rain attenuation revisited

Millimeter frequency satellite links are prone to variations in attenuation over a large range due to rain, more than 30 dB. Traditionally, it has been considered to be part of meteorological conditions, unavoidable variations. Statistical distributions have been fit-to-data type with little or no physical insight. It is the purpose of this paper to test the hypothesis that the dynamic variations are Ricean or Rayleigh type fading, caused by multipath from the rain. This opens the possibility of exact distributions of Doppler variations and of the recently studied rain fade slope, which must follow a Student's t-distribution with the Doppler spread as parameter. The theory is tested on experimental data published in [1].