Research On Characteristic Of Radio Waves Propagation In Deep Space Communication

Deep-space communication is usually considered as the communication and connection between the aircraft which has been left earth satellite orbit and flown into the solar system and the station on the earth ground. The distance of the deep-space communication generally reach hundreds of thousands of kilometers, and even above. In the process of the radio waves sent back by the aircarft to the ground station, some influencing factors both of near-earth space and deep-space have impact on radio waves propagation because of the complexity of the environment. Due to different mechanisms of these factors, the effect is different. In this paper, the inifluence of various factors which have effect on the process of deep-space communications radio waves propagation are discussed by building model and taking simulation. Qualitative analysis and quantitative calculation are carried out at the same time in order to ensure the level that these impact factors contribute. On the basis above, the performance and even the margin of a communication link of deep-space are evaluated and estimated, approximately. The analysis result can be treated as a reference to the design of earth stations and aircraft in deep-space communications.For one thing, the deep-space communications link such as mars exploration intermittent characteristics are analysed in this paper. The earth's rotation and revolution and the mars'revolution are involved to find out the coordinates of the mars in a moment. At the same time, the distance between the mars and the ground station can be obtained, as well as the elevation and the propagation loss. Using this method and model, immediate visible of mars and the loss of radio waves can be calculated.For another, some influencing factors which have effect on the radio waves propagation in deep-space communication both in near-earth and deep-space enviroment are pointed out and analysed. Thanks to the different mechanism of them, the factors are analysed separately. The factors in near-earth enviroment such as vapour, oxygen, rainfall, cloud and the ionosphere are presented. It turned out that the rainfall is taken for the primary element which have wost influence on radio waves propagation. On the other hand, the factors in deep-space enviroment such sloar wind and cosmic noise are illustrated as well. The sun can be treated as the main influence factors in deep-space communication.The final section of this paper discusses the deep-space communication link performance on X-band and Ka-band on the basis of the analysis of influence factors above. Presenting the aircraft and ground station's configuration firstly, the link profermance at X-band without the impact of the sun and the profermance at X-band and Ka-band with the impact of the sun are all displayed, during which the margins are given together. Based on these answers, we find that the link at Ka-band has better performance than X-band, and the bit rate can be increased appropriately in order to achieve better link capacity.