Research On Vertically Coupled Bandpass Filter Based On Integrated Substrate Gap Waveguide

As a new type of transmission structure,Integrated substrate gap waveguide(ISGW)was originally proposed in 2016.The structure is mainly composed of a microstrip transmission ridge in a dielectric plate and an electromagnetic bandgap(EBG)structure periodically distributed around the microstrip transmission ridge.Based on the ISGW structure,this thesis studies and designs four bandpass filters that work in the K and Ka frequency bands through vertical coupling.There are three vertical coupling methods proposed in this thesis,microstrip and microstrip,microstrip and cavity,cavity and cavity.The main research work is as follows:(1)The ISGW resonant cavity is proposed on the basis of the ISGW structure.The resonant cavity is realized by removing a part of the EBG structure.The length of the resonant cavity can be adjusted to obtain the resonant point of the Ka band.Therefore,based on the ISGW resonator,this paper proposes a single-passband filter and two types of dual-passband filters.(2)Firstly,a single-bandpass filter with a slot vertical coupling based on an ISGW resonator is proposed.The filter is composed of two identical ISGW resonators placed back to back.The coupling is achieved by etching a double rectangle on the common ground in the middle.At the same time,the microstrip is used to realize power feeding,and a triangular load is added to the microstrip terminal to form an SIR structure.This single passband filter realizes the above three types of vertical coupling modes.The center frequency of the filter is 26.2GHz,and the passband is in the frequency band of 24.7GHz to 27.7GHz.In this frequency band.On the basis of the above single passband filter,two double passband bandpass filters based on ISGW resonator are proposed.The double passband-? type filter is mainly because the microband part has changed,so the SIR structure is used to determine The specific size of the filter.After simulation and optimization,the center frequency of the filter is located at 25.3GHz and 31 GHz,and the 3d B bandwidth is 24.7GHz-26 GHz and30.3GHz-31.7GHz respectively.Both the microstrip part and the slot part of the doublepassband-? filter have changed,so this paper does not conduct a theoretical analysis on it.The center frequency of the filter is located at 27.3GHz and 31.9GHz,and the 3d B bandwidth is 26.6GHz-28 GHz and 31.6GHz-32.2GHz respectively.(3)A slot-line vertical coupling band-pass filter based on ISGW is proposed.The filter is composed of two ISGW structures back-to-back,and the coupling is realized through a common-ground slot-line structure.The single-pass band filter realizes the above-mentioned microstrip-microstrip vertical coupling mode.The center frequency of the filter passband is located at 29 GHz,and its passband spans the frequency range of28.4GHz to 29.6GHz.Outside the passband,the attenuation effect of the filter on the signal in the stopband is better realized(where the high frequency is less than-30 d B,and the low frequency is less than-20 d B).