Design Of SIW Bandpass Filter Based On Optimization Of Lossy Coupling Matrix

As the key component of RF front-end,microwave filter plays an important role in intelligent terminal,satellite navigation,radar detection and other communication applications.In recent years,substrate integrated waveguide(SIW)has attracted much attention due to its advantages of high power capacity,high quality factor,low insertion loss and easy integration of microstrip planar circuits.Therefore,it is of great significance to study the high performance and miniaturization technology of SIW filter.However,at present,for the filter design optimization stage,most of them still rely on human experience to debug repeatedly to obtain the ideal results,which is blind and time-consuming.In view of this,this paper introduces simulated annealing algorithm to optimize the coupling matrix of lossy filter to replace the optimization process of HFSS exploratory parameter adjustment,so as to improve the efficiency of filter design.MATLAB and HFSS electromagnetic software are used to co-simulate and design two different types of dual pass band filters,which further promotes the research on the theory and method of SIW structure filter miniaturization design.The main research work is as follows:First of all,in view of the low accuracy of filter modeling and the time-consuming optimization,a method of using simulated annealing algorithm to optimize the coupling matrix of non-uniform Q-value lossy microwave filter is proposed,which eliminates non-ideal factors such as phase loading and loss.The optimization and accurate extraction of the coupling matrix are realized,and the effectiveness of the method is verified by the example simulation using HFSS.Secondly,using the aforementioned dissipative coupling matrix optimization method,we design a small dual bandpass filter based on the Quarter-Mode Substrate Integrated Waveguide(QMSIW)loaded symmetrical microstrip open branch(Microstrip Open-Stubs,MOS)structure,which is based on the above 1/4 methods.The filter uses the fundamental modes of two qmsiw resonators and the quasi TEM modes of a pair of MOS resonators to form two relatively independent passbands.The center frequencies of the filter are 5.39 GHz and 10.12 GHz,and the3 d B bandwidths are 11.48% and 4.34% respectively.Three transmission zeros are generated by mode cross coupling and slot hybrid coupling,which significantly improves the selectivity and out of band suppression of the filter.The effective size of the filter is about 0.63 ? g × zero point three four ? g.Compared with the traditional design,it is reduced by 75%,which greatly meets the requirements of high integration of microwave devices in communication system.Finally,in order to further improve the performance of microwave circuit against environmental noise and electromagnetic interference,a high selective circular cavity SIW balanced dual pass band filter is designed.The filter uses the first degenerate mode TM110 in the upper and lower circular SIW dual-mode resonators to construct the differential mode dual-pass band by magnetic coupling through the rectangular slot lines etched on the common metal surface.The filter uses different number of through-hole perturbation to generate different degrees of disturbance,which realizes the mode separation and makes the two passbands independently adjustable.Through HFSS simulation and optimization,the center frequency of the balanced dual band filter is located at 5.39 GHz and 10.12 GHz,the 3d B bandwidth is 11.48% and4.34% respectively,and the common mode suppression is 42 d B and 35 d B respectively.Compared with the traditional balanced filter,the proposed filter has a more compact structure and a wider common mode rejection range.