| With the expansion of space field and the demand of high quality communication,space optical communication technology has become an international research hotspot because of dozens of advantages such as light weight,small size,large capacity and anti-interference ability.Space optical communication is a comprehensive research project that integrates several key technologies,and still faces technical problems.As an indispensable part of the entire space laser communication system,the optical antenna occupies an extremely important position since its transmission efficiency directly determines the quality of space optical communication.In order to ensure that the spatial optical communication system can provide stable and reliable transmission service with high precision technical performance under harsh environmental conditions,it is necessary to further study and analyze the main performance of the optical antenna.Therefore,according to the literature and practical engineering needs,this paper chooses Cassegrain antenna as the main research object of which the optical transmission performance is studied and analyzed.Firstly,the effect of linear thermal expansion on the antenna transmission performance is discussed when the optical antenna is in thermal environment.Furthermore,a structure-optimized design scheme of Cassegrain optical antenna is proposed to aim at the problem of energy loss caused by the central obstacle from the secondary mirror of the traditional Cassegrain antenna.This design is thoroughly analyzed,simulated and studied.The main contents of this paper are as follows:(1)The advantages and research significance of space optical communication are summarized after the development trend of space optical communication both at home and abroad being studied.After that,the theme of this paper is put forward through the analysis of key technologies of space optical communication.(2)This paper introduces the basic theory of optical antenna system and the classification of antenna,and summarizes the main features of various types of optical antenna.Based on the analysis of the basic structure,working principle and characteristics of several common optical antennas,the paper summarizes the key points of designing optical antenna,which provides a solid theoretical foundation for the design,analysis,research and simulation in the follow-up content.(3)The surface equations of the paraboloid and hyperboloid reflector under linear thermal expansion are deduced by the theory of linear thermal expansion.In addition,the two modules including Cassegrain transmitting antenna and Cassegrain receiving antenna under the linear thermal expansion are analyzed after modeling respectively.With the aid of the vector reflection theorem,the ray tracing simulation results of the transmitting antenna and the receiving antenna are given respectively,and the performance of the antenna is analyzed and summarized.(4)Aiming at the problem of energy loss caused by the central obstacle from the secondary mirror of the traditional Cassegrain antenna,a new design scheme of Cassegrain optical antenna with pairs of cone–parabola mirrors and chamfers is proposed.After that,the theoretical derivation process,the optimized structure parameters,and the analysis of the performance are given.The simulation results are exhibited. |
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