Bandpass Filter Design Based On SIW Resonator With Circular Patch

Composite multi-layer substrate integrated waveguide(SIW)structure is a new type of cavity structure which has been widely concerned in recent years.It combines a series of advantages of substrate integrated waveguide resonator and microstrip cavity.It not only has higher quality factor and lower radiation loss than microstrip resonator structure,but also has the same size of SIW resonator structure,which is conducive to the processing and integration of microwave engineering.Firstly,in this paper,two kinds of resonators are analyzed,circular SIW resonator and circular patch resonator.The formula of electric field standing wave distribution and the calculation formula of resonant frequency of each mode is given.Then,the correctness of the resonant frequency formula is verified by the intrinsic mode simulation test,and the test results are compared with the simulation results of the composite multi-layer circular patch SIW resonator,which verifies the feasibility of the composite multilayer structure.Secondly,two kinds of perturbation structures are introduced into the circular metal patch,and the effects of the two structures on the multiple modes of the resonator are discussed by simulation.Then,a single cavity dual passband filter is designed based on the SIW resonator with multiple layers of circular patches and perturbation.The filter is verified by comparing with the test results of the actual product.Finally,in order to improve the out of band suppression ability of the dual pass band,a double cavity composite multilayer circular patch SIW double passband filter is designed.The influence of coupling parameters on the S parameter of the filter is analyzed by simulation,and the related parameters are optimized,and compared with the results of single cavity filter.Then,the real object is tested,and the problem of parasitic passband is simulated and analyzed.At the same time,the simulation results of SIW double passband filter with three cavity composite multilayer circular patch are given.In the above research,the single cavity dual passband filter is designed with a novel composite multilayer circular patch SIW resonator structure.The two pairs of degenerate modes are respectively a pair of low order degenerate mode TM110 of circular patch resonator and the first pair of high-order degenerate mode TM110 of circular SIW resonator.The center frequencies of the passband are 1.99 GHz and 3.39 GHz,respectively.The multi cavity filter constructed in this paper can further improve the out of band suppression effect of the single cavity filter.Two transmission zeros are introduced between the passbands to improve the stopband performance and enhance the selection characteristics.