| With the rapid development of science and technology, people have a higher pursuit of life, we pursuit of faster communication, such as voice transmission, data transmission, and video calls, etc. Simultaneously, electronic components processing as well as integrated circuit technology makes a variety of communication devices available, wireless communications will be the trend of the times. Microwave filter is the key technology of wireless communication systems, providing the center working frequency selection in the microwave band, whether in the signal transmission or reception. Additionally, it also plays an important role in mobile communications, radar, positioning and navigation system. Based on this demand, the design of microwave filters dedicated to smaller, lighter, and better performance, wherein the dielectric multi-mode filter is an ideal solution.The research focuses on dielectric multi-mode filter, and the main contributions of this dissertation can be summarized as follows.:First of all, the background of RF microwave communications is introduced, and the domestic and foreign research work on dielectric multi-mode filter is summarized and presented, with analysis of the principles.Secondly, the filter design methods and rationale are introduced, including low-pass prototype integrated method, combining the coupling matrix method, providing the corresponding theoretical support for following work.Moreover, we do research on the rectangular cavity multi-mode filter research. Based on analyzing on the single-cavity rectangular cavity, the method of degenerate resonant excitation, mode coupling, and generating transmission zero is applied on multi-cavity designs. Suppressing the high-order mode by introducing coaxial resonator, two three-cavity design of four-mode filter LTE band are designed, and constituted of a diplexer by using a 1-2-division connectors for impedance match. Meanwhile, the dielectric-cavity filter can reduce the volume efficiently by filling the entire rectangular cavity with dielectric, with CST simulation verification.Furthermore, we do the research on the dielectric dual-mode filter. Based on the dielectric dual-mode cell and the topology analysis, multi-cavity dielectric multi-order dual-mode filter are designed. The study includes: dielectric dual-mode filter based on patch structure, screw structure, and slot structure. Selecting the appropriate resonant modes, designing the frequency and coupling control structure, and extracting the corresponding value curve, variety of multi-cavity dual-mode filters are designed. Additionally, the filter performance will be greatly improved when introduced cross-coupling.Finally, a multi-mode band-pass filter based on SIW(Substrate Integrated Waveguide) technology is simulation designed. The introduction of source-load coupling generating additional transmission zeros which improves out-of- band rejection performance.All the proposed filters are simulated by CST software. Due to the complexity of processing dielectric resonator, part of the filter structure is complete programmed, simulation and experimental results agree well with the curve. |
