Research And Design Of Reflector Antenna And Multi-Band Feed System

Satellite communication is an indispensable part of the field of mobile communication because of its wide coverage,not limited by geographical factors,and playing a complementary role to the ground communication system.Reflector antenna has been widely used in satellite communication system for its advantages of high gain,simple and stable structure and high power capacity.With the rapid development of information technology in recent years,larger communication capacity and faster communication speed are required.Therefore,the development trend of antenna technology is bound to develop towards highfrequency,broadband and multi-frequency bands.Reflector antennas have great advantages in this regard,and have become one of the research hotspots in recent years.The frequency characteristics of the reflector antenna mainly lie in its feed and feed network technology.This thesis takes the reflector antenna and its feed network as the main research object,and the content covers the following parts.1.Introduction to the reflector antenna and its feed network.The current status of satellite communication,the development of reflector antennas,and the development and status of feed technology at home and abroad are briefly introduced.The basic principle and performance advantages of the currently widely used ring focus antenna are briefly analyzed,and according to the actual requirements of engineering applications,the implementation scheme of a Ku/Ka multi-band integrated feed network is presented,and some components in the feed network are briefly analyzed from the aspects of principle and performance requirements.2.Ring focus reflector antenna design.In order to avoid the feed blockage of the traditional double reflector antenna,the ring-focus dual reflector antenna is designed.A wide flare angle corrugated horn working in Ku/Ka multi-band is designed.By optimizing its structural parameters,the antenna has a suitable irradiation level distribution within ±40° irradiation angle,and the sub-surface structural parameters are optimized,so that the efficiency of the ring focus reflector antenna is higher than 63% in the Ku/Ka multi-band broadband range.3.K/Ka dual-band broadband feed network design.Feed network devices such as broadband circular polarizers,ortho-mode transducer and filter are designed for K/Ka dual frequency bands.The circular polarizer adopts a square waveguide with four-ridge structure.The phase shift range of 90±3° is achieved in the wide frequency range;the ortho-mode transducer adopts a structure that is easy to be processed i,which is convenient for precise processing and manufacture.The voltage standing wave ratio of each port in the feed network is less than 1.23,and the isolation degree of the transceiver port is greater than 110 d B.4.Research on Ku/Ka dual-band integrated broadband feed system.The key component of the feed network is designed,and the Ku signal is coupled out in the form of a quadrature junction to separate the Ku-band signal from the Ka-band signal;a block mode filter that can effectively suppress high-order modes and parasitic passbands is added to the Ku channel,and combined with a wrinkle filter to improve the isolation of the Ku/Ka band.A Ku-band turnstile and 180° phase shifter is designed for Ku-band polarization tracking.A compact integrated feed network topology is designed,and combined with the ring-focus reflector to conduct the overall design and simulation analysis of the antenna.The results show that the antenna achieves an efficiency of more than 61% in the operating frequency band.5.Ku/Ka dual-band time-sharing feed system design.Aiming at the disadvantage of mutual influence between Ku-band and Ka-band in the integrated feed network,a dual-channel structure with independent Ku-band and Ka-band is designed.The frequency feed network and the Ka frequency feed network are independently connected to realize the time-sharing operation of the Ku frequency band and the Ka frequency band,in addition to eliminating the frequency division system,the interaction between Ku band and Ka band is eliminated,and improve the performance of each feed network channel.