Microwave Planar Dual-mode And Multimode Filter Design And Research

With the rapid development of modern mobile and wireless communication business, the miniaturization of communication systems have become increasingly demanding. In recent years, with the rise of the semiconductor industry, it has made obvious progress in miniaturization with amplifiers, mixers, oscillators et al. active devices of the communication systems. But the miniaturization of passive devices, mainly in antennas and filters, has progressed slowly. It hampered the development of the entire RF and microwave circuit. In this thesis, the dual-mode and muti-mode resonators technique, which is one of miniaturization methods of filters, is studied. The optimization algorithm of cross-coupled filters is discussed. Several instances of dual-mode and muti-mode filters are presented. The ideas in muti-mode filters design are summarized.In ChapterⅠ, the research background and recent developments about dual-mode and muti-mode filters are reviewed.ChapterⅡdescribes the basic theory of filter design, reviews the transfer function forms of traditional filters, frequency conversion, resonator quality factor and so on.ChapterⅢdiscusses around the optimization of cross-coupled resonator filter. First of all, this chapter introduces two basic kinds of filter coupling models:the direct coupling and not direct coupling between source and load. Then, it gives the zero-pole conversion relationship of generalized Chebyshev low-pass prototype filters. Finally, it introduces the optimization algorithm of cross-coupled filters, and starts a detailed discussion on the filter optimization and synthesis examples.ChapterⅣfirst proposes two circular patch loaded hexagonal meander loop resonators, analyzes their modes'characteristics, and synthesizes coupling matrixes of their corresponding filters respectively. Second, this chapter also proposes a square loop loaded dual-mode filter, analyzes the basic principle of center stub-loaded resonator and the coupling matrix and measurement are exhibited finally.ChapterⅤproposes two novel hexagonal triple-mode bandpass filters. By two different forms of capacitive loading unit, one mode resonant frequency declines, while the other modes resonant frequencies remain almost unchanged. The mode characteristics of two hexagonal resonators are also analyzed, and the ideas of filter design are given. Finally, two hexagonal three-mode filters are fabricated and measured respectively.In chapterⅥ, a brief summary of the contents and innovations are given, and future research topics are suggested.