The Miniaturization Research Of Microwave Filter

With the rapid development of modern wireless communication technology, microwave filter, as an integral part of the system, has drawn enough attention of many researchers’ and been conducted in-depth research. High performance, high index, miniaturization, lightweight, low cost has become the major research direction. Based on the practical application of the demand, miniaturization of the coaxial cavity filter and microstrip structure filter has been studied. The main work of this is as follows.Firstly, the miniaturization of high selective coaxial cavity bandpass filter has been studied. Based on the miniaturization of single cavity and filters’ synthesis theory, a five-order comb structure of coaxial cavity filter and a six-order cross coupling model coaxial cavity filter has been respectively designed and processed. As the test parameters and simulation results are basically identical, the filters that have been designed achieve the characteristics of high selectivity, high Rejection and narrow passband.Then, the microstrip interdigital filter have been studied, and some improvements were added into the traditional structure. One added the coupling between source and load, and the other one added DGS structure futher. These improvements add transmission zeroes, enhance the selectivity and the band rejection ability without increasing its size.Finally, by the research and analysis of the stub loaded dual-mode resonator and quarter-wavelength resonator, three tri-band bandpass filters were respectively designed. Each passband can be independently designed to reduce the design difficulty and shorten the design cycle, and has the features of good performance, compact structure and small volume, the method shows highly practical value, and simulation results agree with the experimental results.