Research On Wide Stopband Bandpass Filter Based On Integrated Substrate Gap Waveguide

In modern communication systems,microwave filters play an extremely important role in separating microwave signals of different frequencies.In addition,its research in the fields of communication systems such as radar and electronic countermeasures has also received more and more attention.At the same time,as the application requirements for these systems continue to increase,so do the requirements for filter performance.In addition to requiring it to have excellent passband transmission and sideband selection performance,it also puts forward higher requirements for its miniaturization,wide stopband,and high power capacity.Therefore,on the basis of the Integrated Substrate Gap Waveguide(ISGW)structure research launched in 2016,this paper researches and designs two kinds of wide stopband bandpass filters.The main research work includes:(1)Aiming at the problems of harmonic suppression and out-of-band selection performance of filters,this paper designs an X-band wide stopband bandpass filter based on the structure of integrated substrate gap waveguide(ISGW)and substrate integrated waveguide(SIW).Compared with the filter with SIW structure,its harmonic suppression performance can be significantly improved.The filter is a filter with an electrical coupling structure.The specific implementation method is to etch five dumbbell-shaped slits with different sizes in the SIW,and use the self-encapsulation property of the ISGW structure to encapsulate the underlying structure of the SIW to achieve its Wide stopband performance.In this paper,theoretical and simulation experiments are carried out on the proposed wide-band stop-band filter in terms of equivalent circuit,electric field mode,parameters,etc.performance,its return loss in the passband is less than-16 d B.In addition,there are multiple transmission zeros distributed in the stopband of the filter,so the selection performance of the filter is greatly improved.At the same time,the stopband bandwidth of the filter reaches 2.6f0,realizing a wide stopband.(2)In order to meet the miniaturization requirements of the filter,a narrow-band bandpass filter is studied and designed in this paper.It combines ISGW with a microstrip split resonator structure.Compared with the traditional microstrip split resonant ring filter,its selectivity and stop-band rejection are greatly improved.The filter adopts a new type of hybrid coupling microstrip split resonator ring to realize filtering,and combines it with ISGW structure to reduce unnecessary radiation loss.In this paper,the theoretical and experimental analysis of the proposed narrow-band band-pass filter in terms of equivalent circuit and parameters are carried out.Excellent narrowband performance.The filter produces three poles in the band,and the return loss in the pass band is less than-16 d B,and there are several transmission zeros distributed in the stop band,which greatly improves the selection performance of the filter.At the same time,its stopband bandwidth reaches 1.6f0,realizing a wide stopband.Compared with the filters proposed in other literatures,the filter has good wide stopband performance in high frequency band and good out-of-band rejection performance.