Research On Atmospheric Combined Attenuation Effect On Millimeter Wave System

In this paper, the constitutions and characteristics of millimeter wave communication system are expatiated. The atmosphere factors influence on millimeter wave system are analyzed and discussed. The absorption of oxygen and vapour effect on millimeter wave and the attenuation induced by clouds are researched. Rain attenuation prediction models are analyzed and forecasted with the pattern available of ITU-R. Then, the attenuation at Xi'an area, as one of the typical stations is calculated by connecting the parameter of N-STAR in Japan with the contribution of rainfall statistically in Xi'an, the curves of specific attenuation index and decrement varying with factors such as rainfall and frequency are available. Based on analyzing the particle size distribution of sand-dust, combining the complex dielectric constant of dry sand and pare water (Raised by double Dby), the calculation model of the sand attenuation is produced, using partical scattering theory and method of equal effects of mixture dielectric constant. The attenuation of sand-dust produced by explosion, vehiele and nature is analized by the model. Using the result of numerical calculation, the attenuation rate of sand-dust changed with millimeter wave frequency at different moisture is simulated, then, the conclusions are gived. Furthemore the multiple scattering on the attenuation for millimeter wave in sand-dust storms analyzed. Lastly, based on the model of combined attenuation given ITU-R, the attenuation of millimeter wave caused by combined effect of gaseous absorption, clouds and rain attenuation is studied, and the relationship of combined attenuation of gaseous absorption, clouds and rain as a function of the frequency is obtained, and the results is analyzed and discussed. The actual application of combined attenuation whether or not sand-dust and effect on millimeter wave radar is studied. This research is important for developing the millimeter communication, remote-sensing and so on system in civil and military applied to desert region.