Scattering of electromagnetic radiation by precipitation particles and propagation characteristics of terrestrial and space communication systems

摘要

The results of applying the Fredholm integral equation method of solution to the scattering of electromagnetic radiation from oblate spheroidal raindrops for the communication bands 4, 6, 11, 14, 20, 30 GHz are presented in the paper. These scattering amplitudes are then used to calculate propagation characteristics such as attenuation, phase rotation and crosspolarisation of a rain-filled medium. The validity of using the Van de Hulst single-scattering equation is considered, and conditions for its use presented. A new and more general relationship between horizontal and oblique propagation characteristics is presented which uses only the horizontal and zenith conditions to derive all others. Using Brussard's meteorological model for raindrops a new and more general model for the medium containing canted raindrops is presented. Attenuation and crosspolarisation equations are derived for both linear and circular polarisation for this model, which assumes a stochastic model for the canting-angle variations. Finally, the specific cases of terrestrial radio-relay links and satellite communication links are considered, and detailed results presented for each. A comparison of the theoretical results with experimental results for linear and circular depolarisation at 11 GHz is also given.