Research On Cavity Multiple-Mode Filters

As human society accelerates into information age,the communication industry and relevant sectors continue to flourish.The RF front-end circuit,which links the antenna and the RF transceiver module is the core component of the wireless communication system and is being widely used in communication field.The RF filter,which acts as anti-interference and filtering noises is the essential component among the RF front-end circuit.Nowadays,the rapid development of 5G communication coupled with stringent requirement for filter ushers in the massive exploration of RF filters.This dissertation aims to study multiple-mode cavity filter,which is a important kind of RF filter.The research contents include metal cavity multiple-mode resonators and filters as well as dielectric multiple-mode resonators and filters.The technique difficulties and innovations are as follows:(1)In order to resolve these difficulties on traditional dielectric filter design,a dual-mode dielectric filter with patch coupling method and a triple-mode dielectric filter with slot coupling structure are proposed.(2)In order to deal with these problems in conventional cavity filter,a novel quadruple-mode cavity resonator and filter is proposed after analyzing the mechanism of the generation of resonant modes.The resonator can achieve miniaturization by increasing the number of resonant modes.Combining with parallel coupling topology,a filter with wide-spurious free window is achieved without introduction of numerous coupling structures.(3)Ordinary coaxial resonators are often used to design single mode filters due to their TEM mode resonant characteristics.In this research,by referring the theory of parallel coupled line,the number of coaxial inner conductors is adjusted and a novel odd-even dual-mode coaxial resonator is realized.A filter with controllable transmission zeros based on the resonator is also designed.In addition,a dual-mode coaxial resonator is realized by adding a circular sleeve outside the coaxial inner conductor,and a dual-frequency filter is designed by using the proposed resonator.