Role of particle-size distributions on millimetre-wave propagation in sand/dust storms

Particle size distributions of sand and dust are surveyed. Various assumptions for the theoretical prediction of the effect of particles on MMW propagation are discussed and justified. A general formula of the propagation parameters, for any particle shape and any distribution, is developed. It is found that the MMW propagation depends strongly on the probability density function of particle size distribution. A simplelinear relationship is shown between `¿¿, ¿¿¿¿ and an `effective radius¿¿ of the storm. Attenuation and phase shift due to spherical and ellipsoidal particles are calculated for four distributions, namely power law, exponential, lognormal and normal. Results are presented and the role of the distributions is discussed