Relationship between path length and attenuation of radio waves transmitted in a uniform rain-filled medium

It has been accepted that rain attenuation (in an environment in which the rainfall rate is assumed uniform along the whole length of the radio link) is linear with respect to path length. It is shown here that for nonspherical raindrops this is not generally the case. Results over the frequency band 3–30 GHz are presented. These demonstrate that, in certain circumstances, use of the path-length-related model for linear and circular polarisations can lead to significant errors.