Effect of scattering in measurements of rain attenuation by passive radiometry

Abstract

A sun-tracking beam-switching radiometer has been used at a frequency of 37 GHz to measure attenuation caused by rain on earth-space paths. The attenuation derived indirectly from data on the thermal noise emitted by the rain underestimates the true attenuation by 10 to 15% and 30 to 35% for vertical and horizontal polarisations, respectively, for elevation angles in the range 10°–35°.