| In this thesis, the characteristics of Ka band and its development and application at home and abroad are introduced. The physical property of rain and the impact mechanism of radio propagation by rain are expounded; the concept of raindrop size distribution, its measuring methods and the formula of different distributions are stated. The computational method of specific attenuation is introduced and seven types of the most prevalent rain attenuation models (Crane Global model, Assis Einloft Improved model, SAM model, DAH model, ITU R model, UK model and China model) are summed up, along with their characteristics, parameters and computational procedure. The measuring system's structure about the characteristics of rain attenuation and the experimental scheme are presented in details, together with different modules'function, experimental parameters and the detecting, recording and the primary processing methods of experimental data. The specific attenuation under different parameters and raindrop size distributions is simulated in Matlab programs, discussed and analyzed with charts. Meanwhile base on the ITU R model and combing with the geographic information about Xi'an in earth space communication link, the specific attenuation, the equivalent pathway length and the rain attenuation are simulated and calculated in Matlab programmes varying with the working frequency, rain rate and the antenna elevation angle. The experimental raindrop size distribution are analyzed and compared with the theoretical distribution; the atmosphere attenuation model is introduced and rain attenuation is calculated by using experimental data in Matlab programmes and compared with theoretical value and then the following work and direction of experiments are proposed.
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