Design Of Bandpass Filter Based On Substrate Integrated Waveguide

With the rapid development of wireless communication networks,the design of radio frequency microwave circuits has become a hot research topic.The filter is an indispensable part of the radio frequency microwave front-end circuit,and its performance will directly affect the performance of the entire front-end circuit.Therefore,people have higher requirements for the miniaturization and precision of filter design.At the same time,as frequency bands become increasingly crowded,how to use frequency band resources more fully and rationally also puts forward higher requirements on the performance of multi-frequency filters.In this context,the Substrate Integrated Waveguide(SIW)structure is widely used in the design of various filters due to its high quality factor,high power,low loss,small size,and ease of integration.Based on the development stage of 5G communication,this paper designs a dual-pass band filter by loading a set of completely asymmetric complementary split ring resonators(CSRR)structure technology on the basis of SIW,and adopts a linear transition transition band.The impedance matching between the SIW structure and the microstrip line is realized,and the filter has good transmission and stop-band suppression.In this paper,three filters are designed.The center frequencies of the two passbands of each filter are 3.5GHz and 4.5GHz,and the bandwidths are 800MHz/600 MHz,600MHz/500 MHz,and 1GHz/400 MHz respectively.Each filter can meet the requirements of insertion loss loss S21 lower than-20 d B and return loss S11 higher than-3d B in the pass band;in the stop band,the S11 parameter of the round square combined with CSRR structure can reach-40 d B.The S11 parameter of the circular hexagonal CSRR structure is lower than-45 d B,and the S11 parameter of the square CSRR structure is also lower than-45 d B.All the above simulation analysis uses HFSS,CST,ADS and other software.The simulation test content mainly includes electromagnetic field intensity distribution,resonance point position and S parameter test.The physical models of the first-order structure,the second-order round square combined with the CSRR structure and the second-order round square combined with the CSRR structure with the transition transition zone were processed.The actual dielectric boards are made of Rogers material with a dielectric constant of 2.2,and the structure is connected with an SMA interface.The physical test results and the simulation results have a high degree of fit,which effectively proves that the filter has a high practical value.And these three filters can be easily integrated into miniaturized microwave circuits,with good design flexibility,and have practical reference value for the application and development of 5G communications.