Design And Research Of Multimode Multiband Filter Based On Substrate Integrated Waveguide

The RF filter is one of the indispensable passive components in the RF communication circuit.The RF multiband filter can effectively increase the efficiency of the filter and reduce the filter volume.In recent years,it has become a research hotspot of RF filters.Based on the substrate integrated waveguide(SIW),this paper analyzes and designs several multiband filters using the mode disturbance and multimode coupling principles,and achieves better performance indicators.This paper firstly analyzes the multimode resonance characteristics of the SIW structure,and gives the theoretical analysis of the mode disturbance,and studies the cross-coupling mechanism between the modes and the signal transmission path.Based on these analyses,three multimode multiband filters based on SIW structure are designed.Firstly,the perturbed metalized via-holes are introduced to realize a multimode dual-band filter based on a single rectangular SIW cavity in this paper.And four transmission zeros are introduced for the filtering response because of the cross-coupling between multiple modes,which achieve good out-of-band rejection.The distance between the two passbands can be controlled by moving the disturbed holes without changing the size of the filter.Compared with other dual-band filters reported in the literature,the filter designed in this paper is not only simple in structure,but also has high flexibility and good out-of-band rejection.Secondly,based on the research of multimode rectangular SIW structure,the multimode tri-band filter is realized by the proposed multiband design method.The filter vertically couples two SIW cavities operating in the fundamental mode to a multimode rectangular SIW cavity,and implements a tri-band response based on the concept of double behavioral resonance.Similarly,there is cross coupling between multiple modes within the cavity,resulting in six transmission zeros.The proposed design method is verified by experimental measurements,and the designed filter has the advantages of high performance and simple structure.Finally,a miniaturized dual-band filter is designed in this paper.Flexible control of the resonance modes is achieved by loading the ridge waveguide structure and embedding the open stripline.In order to generate a quasi-elliptic response at the passband and increase the out-of-band rejection,two ?/4 stubs are loaded on the open stripline,resulting in two transmission zeros.This filter has the advantages of compact size,high flexibility and more transmission zeros.The performance of the multiband filter designed in this paper has reached the same level as the same advanced filter at home and abroad.