Research On High Performance And Miniaturized Planar Microwave Passive Components

With the rapid development of modern wireless communications technology, higher requirements are required for passive components in the system. High performance, miniaturized microwave passive components and synthesis methods of passive components are the popular and difficult problems in the research area. To solve these problems, some design schemes for planar microwave passive components and synthesis method have been proposed in this dissertation. And theoretical models have been established. Based on these schemes, several planar microwave passive components with high performance and compact size have been designed.In Chapter1, research background and significance of microwave passive components in wireless communication systems are introduced. Then, recent developments about high performance and compact microwave passive components in modern wireless communication systems are reviewed. Although many researchers have done much work on high performance and compact microwave passive components, most of the research methods rely on the simulation softwares. Thus, synthesis method is particularly important in this case.In Chapter2, the fundamental theories of microwave filter design have been reviewed. Based on the study of the fundamental theories, models of modified multiple resonant peaks resonators have been proposed. Then some models of ultra-wideband (UWB) bandpass filters with notched band have been proposed. Due to the difficulty of realizing multiple notched bands within the UWB passband, a design method about compact UWB bandpass filter with two notched bands has been proposed based on defected ground structure (DGS) technology. The proposed UWB filter has competitive advantages on the size and controllable notched bands compared with recently proposed UWB bandpass filters with dual notched bands. Based on the investigation of dual-mode resonators, a novel dual-mode bandpass filter with three transmission zeros has been proposed to improve the stopband performance. The proposed dual-mode bandpass filter has competitive advantages on the stopband performance compared with recently proposed dual-mode bandpass filters. In Chapter3, based on the study of synthesis approach of traditional equiripple responses for wideband bandpass filter, a novel synthesis method of non-equiripple responses for wideband bandpass filter has been proposed. The dimensions of the wideband bandpass filter derived from the proposed synthesis method can be used to design wideband bandpass filter directly. Based on the proposed synthesis method, the detailed derivation of even number and odd number of transmission poles within the passband is introduced. Then, based on the synthesis approach of non-equiripple responses for wideband bandpass filter, wideband parallel-coupled line bandpass filters of even number and odd number of transmission poles with non-equiripple responses have been proposed. The sensitivities of the proposed filters are analyzed. The results show that the substrate loss, conductor loss and manufacturing errors have less influence on the non-equiripple filters than traditional Chebyshev filters.In Chapter4, the fundamental structure, network model and technical parameters of balun are introduced. Then the basic theory of ring resonator is reviewed. Based on the study of these theories, a model of dual-mode balun bandpass filter has been proposed. The proposed balun can improve stopband performance effectively.In Chapter5, the structures and working principles of T-junction power divider and Wilkinson power divider are introduced. Based on the study of these theories, a model of wideband bandpass power divider has been established for wideband communication systems. Based on the even-and odd-mode analysis method, the equations of transmission poles and transmission zeros have been deduced. The theoretical frequency locations of transmission poles and transmission zeros have been given. By properly adjusting the locations of the transmission zeros, the harmonic can be supressed to improve the stopband performance.In Chapter6, the research of this dissertation is summarized and future research is predicted.