Raindrop size distribution profiling by laser distrometer and rain attenuation of centimeter radio waves

Abstract

The paper describes system design of laser distrometer, its calibration process and profiling of raindrop size distribution (RSD). Here, raindrop signature is extracted by allowing the drops to pass through a controlled field of view of a sensor. A laser beam works as signal source, phototransistor as detector-cum-amplifier and optical fibers as trans-receiving ports. RSD profiles and rain rate at different weather conditions have been presented. Specific raindrop attenuation of line of sight radio signals at 10 - 30 GHz of various drop diameters is then calculated by using standard attenuation equations and model values of scattering functions. Finally, the rain attenuation magnitudes are compared with those given by a model framed earlier [Timothy K I, Sharma S, Devi M & Barbara A K, Model for estimating rain attenuation in frequencies range 5-30 GHz, <i style="">Electron Lett (UK),</i> 31 (17) (1995)].