Design And Research Of Planar And Multilayer Microwave Filters

Microwave filters are vital components in communication system. With the constantly updating of the communication technology, the performance of the microwave filters has to be improved. Miniaturization is one of the development tendencies of the microwave filters. In this background, the planar and multilayer microwave filters are studied in the thesis. The main work is as follows:(1) A kind of planar reconfigurable bandpass filter is proposed. Two varactors are used in the filter to realize adjustable passband in the frequency range from 3.2GHz to 3.82 GHz. Passband of the filter is kept around 120 MHz and the rejection in the stopband is large. The filter has a simple structure and smaller size.(2) Four kinds of dual-mode bandpass filters with novel perturbation elements are designed. All of these filters use square patch resonator and the CSRR structure, single ring structure, two rings structure, three rings structure are used as perturbation elements. The performance of the above perturbation elements on the dual-mode filters is studied and the effects of the perturbation elements on reducing filter size are analyzed. The four kinds of filters are fabricated and measured, and the measurement results and simulation results are basically consistent.(3) A multilayer bandpass filter based on LTCC technology is proposed. The filter uses a multi-layer structure and the design of planar structure is changed to a three-dimensional structure, which effectively reduces the filter size. The relative dielectric constant of the dielectric material is 7.8 in the bandpass filter. The center frequency of the filter is 10 GHz and 3dB relative bandwidth is 32.4%. Entire LTCC bandpass filter size is 3.2×1.6×1.7mm3 and electrical size is ggg??16.015.030.0???. The simulation results of the designed LTCC filter are analyzed and the prototype is fabricated. Good agreements between simulated and measured results are observed.