Miniaturization Of Microwave Filter And Duplexer Research

With the rapid development of modern communication technology, the wireless communication systems put higher requirements forward on performances and sizes of microwave filters. Recently, the research of microwave filters with high performances and miniaturization becomes popular. Microstrip and substrate integrated waveguide (SIW) filters, with smaller sizes and optimum performances, are widely used. In addition, the evanescent-mode waveguide filter that is with a small volume, compact structure, low insertion loss, wide stop band, large power capacity and potential application in the ground stations, satellite communications and other fields is highly valued.Firstly, planar miniaturized filters are researched in this paper. Traditional microstrip lowpass, interdigital bandpass, and SIW shunt dual passband filters are improved into smaller sizes and the efficiency of design is also improved. Via experiment, the results show good performances.And then, double ridges and single ridge evanescent-mode waveguide filters are researched deeply, which a more efficient and accurate design method is summed up. Via this method, a Ku-band filter is designed. Via experiment, the results and simulation curves agree well, which verifies the feasibility, accuracy and reliability for this method. Meanwhile, based on the design above, this paper proposes a novel structure to design the evanescent-mode waveguide dual-band filter with small size and good performance. Via experiment, the result shows test performance achieves the expectations. In addition, a novel duplexer is also designed in this article, whose structure is very compact. And the design method is very simple. The experiment result shows a good performance, which verifies the correctness of the design method and the rationality of the structure.