A Practical Model for Rain Depolarization Evaluations at Centimeter and Millimeter Wavelengths

For modern satellite/earth communication systems, such as those involving high-data-rate TDMA transmission, frequency reuse network, automatic power control algorithm, and diversity switching, the present model for estimating instantaneous microwave depolarizations, based only on widespread rain, is still far from adequate. widespread rain, showers, and thunderstorms are three completely different types of rain all having distinctively unique characteristics, and they should be modeled separately. An assessment of microwave propagation degradations for the three rain types is therefore a necessary first step toward the establishment of a practical model for modern communications applications. In this paper, a new set of distributions, based on over 30 measurements of raindrop sizes under different meteorological conditions, is proposed for slant-path transmission to replace the conventional Laws and Parsons distribution. The basic propagation parameters, i.e., specific attenuation and specific phase shift, are evaluated, and comparisons with existing models are made. The results provide an updated practical model for rain depolarization evaluations at centimeter and millimeter wavelengths.