Research On The High-Performance And Compact Microwave Passive Components

Microwave passive components are important parts of modern wireless communication systems, so the design and implementation methods for their high-performance and miniaturization have been the crucial goal of the wireless communication RF system development. Up to now, a series of novel methods such as the use of dual/multi-mode structure, the multilayer structure and defected ground structure etc. have been put forth and made some improvements, but there are still many practical problems to be investigated. Accordingly, the following researches are carried out on the high-performance and miniaturization microwave passive components in this dissertation.Firstly, the synthesis method for generalized Chebyshev filter is thoroughly investigated. With the advantage of parallel operation and global search, a stable and efficient method based on genetic algorithms is used to extract the coupling matrix of the generalized Chebyshev filter. And the method provides a theoretical guidance for the filter miniaturization design in the following chapters.Secondly, the miniaturization metal-cavity passive components with dual-mode resonator structure and dielectric loaded structure are researched. Metal-cavity passive components with low-loss and high power capacity are still indispensable in the current high-power wireless communication systems. An extra transmission zero out of the passband can be obtained by using single-cavity dual-mode rectangle waveguide resonator, and a rectangle waveguide duplexer with high out-of-band rejection is developed. A four poles elliptic filter is realized by single-cavity dual-mode circular waveguide resonator. Comparing with the conventional sing-mode structure, the dimension can be reduced by about50%. A hybrid metal-cavity multiplexer with low-loss and high out-of-band rejection is achieved by sing-cavity dielectric loaded rectangle resonator with high Q value.Thirdly, novel microwave passive components with stub-tapped microstrip line are researched. Using stub-tapped microstrip line, the following functions can be achieved:1. an extra transmission zero out of the passband is obtained to improve out-of-band rejection;2. dual-mode resonator is derived to achieve dual-band components;3. slow-wave structure is realized to reduce the length of the transmission line and make the components miniaturization. The equivalent circuit mode of the stub-tapped microstrip line is researched. An improved hairpin-comb bandpass filter with tapped open stubs is obtained. Comparing with the conventional hairpin-comb filter, the out-of-band rejection is remarkably improved by stub-tapped microstrip line. A broadband and dual-band branch line coupler and a coupler line balun are realized by using the duai-band characteristics of the stub-tapped transmission line. Comparing with the other designs, the phase differences of the two output ports in dual-band are both90°, and no additional phase correction is needed.Finally, microwave passive components with microstrip DGS and dual-mode structure are studied. Based on square ring dual-mode resonator structure, the equivalent circuit model for microstrip DGS and dual-mode structure is derived and the frequency responses of this structure are comprehensively analyzed. The novel square ring dual-mode structure with DGS and square ring dual-mode structure with tapped stubs are proposed and three different types of dual-mode dual-band filter are realized. The dimension of the proposed filters can be decreased to about50%of the conventional design. And the structure is compact and easy fabrication.