Design Of Bandpass Filter Based On Substrate Integrated Waveguide

With the rapid development of the modern wireless communication system,the structure of system becomes increasingly complex,the requirements for the performance becomes more strict,and the whole system is getting smaller and more light.In modern wireless communication system,microwave passive devices with high performance is still an indispensable part,especially the passive filter.As we all know,Low cost,high integration,high performance has become the key of modern microwave and millimeter wave technology.Therefore,the substrate integrated waveguide?Substrate Integrated,Waveguide,SIW?technology has great advantages in these aspects.SIW is a structure that can achieve guided wave characteristics on dielectric substrate.The structure itself is characterized by the advantages of microstrip structure and rectangular waveguide structure.The SIW structure is very consistent with the demand for microwave and millimeter development in the future.The main work of this thesis is to study the structure and characteristics of several novel and unique substrate integrated waveguide band-pass filters,and put forward a detailed design method.This work includes the following contents:Firstly,this thesis analyzes the basic theory of filter,such as filter classification,performance index and so on.The basic theory of SIW and the relationship between the SIW and the rectangular waveguide are studied.Then the transmission characteristics of the transition structures of the two SIW-microstrip converters are studied in detail,which provides a theoretical basis for the following design of the SIW-based band-pass filter.Secondly,this thesis analyzes the structure characteristics and transmission characteristics of the three common defected ground structures?DGS?,and proposes two new types of DGS which can meet the design requirements.The influence of these two new DGS etching on the transmission characteristics of SIW structures is studied.According to the above theoretical analysis,combining the characteristics of SIW structure and DGS respectively,two novel SIW-DGS broadband filters with novel structure and excellent performance are designed.Thirdly,in order to further improve the frequency selectivity of the filter,an improved EBG structure is proposed on the basis of the traditional electromagnetic band gap?EBG?structure,and the transmission characteristics and the equivalent circuit are analyzed in detail.A high performance broadband filter is designed by loading DGS and EBG structure onto SIW structure at the same time.In order to further realize the miniaturization of the filter,a half mode high performance broadband filter is designed.A high performance broadband filter is designed by loading DGS and EBG structure onto SIW structure at the same time.In order to further realize the miniaturization of the filter,a half model substrate integrated waveguide high performance broadband filter is designed.Finally,this thesis has used the oversized cavity to design the single passband,dual passband and triple passband filters.The three filters used TE₁₀₁,TE₂₀₁ and TE₃₀₁ mode,and the overall shape of the filter is symmetrical,making the processing easier.By making a lot of simulation analysis,the simulation results of the five SIW filters designed in this thesis are very good,and three of these filters are measured.The results are in good agreement with the simulation results,and have a broad prospect of engineering application.