Research On Multimode Filter Based On SISL Platform

In wireless communication systems,the filter plays a role in signal selection and is indispensable in various congested interference environments.Research on highperformance filters has great implications for the development of microwave radio frequency technology.This thesis combines the advantages of Substrate Integrated Suspended Line(SISL),and uses multi-mode technology for the research and design of cavity filters.The Substrate Integrated Suspended Line uses multilayer printed circuit board technology,which has the advantages of low cost,light weight,low loss,high integration,and self-encapsulation.The circuit designed based on the SISL platform has significant advantages.Simultaneous excitation of multiple modes in a single cavity is equivalent to multiple cavities,which can effectively reduce the volume of the filter.At the same time,the wavelength of the waveguide of the medium with high dielectric constant is shorter,which plays an important role in the miniaturization of the filter.This thesis combines the advantages of the above-mentioned SISL platform,multi-mode theory technology,and the characteristics of high dielectric constant medium to design the filter.This thesis is the first to design a cavity filter based on the SISL platform.According to the filter synthesis theory and the cavity coupling theory,a dual-band dielectric resonator filter based on SISL is designed.The filter uses a high-Q dielectric resonator(DR),which is short-circuited at both ends of the dielectric resonator.In this case,the different TM modes of the dielectric resonator are used to form the two passbands of the filter.By rationally designing the positions of the input and output ports and the degenerate mode perturbation structure,the dual-band filter generates multiple transmission zeros and has the feature of high isolation.At the same time,the filter can be self-encapsulated without processing the metal shell,reducing the processing cost and circuit weight,and the design is highly integrated and easy to integrate with other circuits.In addition,this thesis designs a dielectric-loaded filter based on the SISL platform.This filter has the advantages of self-encapsulation of the SISL platform and ease of integration with other circuits.At the same time,compared with the traditional metal waveguide filter,the filter is loaded with high dielectric constant medium,which significantly reduces the size of the filter.In addition,the filter adopts multiple modes to achieve the design of the filter,which further realizes the miniaturization of the filter design.Besides,the design realizes the required feeder and coupling structure on the PCB circuit board.Compared with the probes and screws used in traditional cavity filters,the feeding structure and the coupling structure are easier to process and lower in cost.