Research And Design Of Integrated Substrate Gap Waveguide Bandpass Filter

Microwave filters are an essantial and important component in communication systems.High Frequency Band filters often designed with Microstrip and Substrate Integrated Waveguides(SIW)have disadvantages such as radiation loss and susceptibility to external electromagnetic interference.The Integrated Substrate Gap Waveguide(ISGW)technology can effectively improve the impact of these disadvantages on performance,so ISGW technology provides new ideas and ways for high frequency band filter design.The main research work of this paper is to design two different types of band pass filters using the two structures of ISGW.The main research work is as follows:(1)A three-layer structure ultra-wideband filter using ISGW technology combined with SIW structure design is proposed.Compared with this type of single-layer SIW structure filter,the performance of the filter is significantly improved.The electromagnetic hybrid coupling filter structure is formed by etching rectangular slots and opening metallized via_holes in the SIW,and then using the ISGW technology to encapsulate the underlying SIW structure to form an ultra-wideband bandpass filter.Equivalent circuit analysis,parameter analysis,electric field mode analysis and other theoretical contents are used to design and analyze the proposed ultra-wideband filter.The simulation shows that the center frequency of the filter is 17.5GHz and the passband range is 14.4GHz-20.7GHz.The relative bandwidth FBW is 36%,with two transmission zeros appearing at 12.9 GHz and 22.1 GHz.The processing test of the designed filter and the comparative analysis with the filter proposed in other literatures show that the filter simulation and test results are consistent and show that the ISGW structure filter is improving the selective performance,reducing the radiation loss,Improve the advantages of self-encapsulation performance.Summarize the design flow of the filter using the ISGW structure to encapsulate the SIW structure design,and design a band pass filter with a center frequency of 15 GHz,a return loss better than 20 dB,and a passband range of 12.98 GHz to 16.64 GHz Device.(2)An Interdigitated bandpass filter designed using ISGW technology is proposed,which improves the filter performance compared to traditional microstrip filters.The microstrip interdigital structure is combined with ISGW technology in the form of transmission ridges to design a bandpass filter with excellent performance.The structure use patch matching and the interdigital filter units are distributed symmetrically in the center.Secondly,on the basis of this structure,two other filters of the same type are derived from the branch-matching interdigital center-symmetric structure and the patch-matching interdigital type axisymmetric structure.Full-wave simulations were carried out on these three filters respectively.The simulation results show that the center frequency of the patch-matched interdigital center symmetric filter is 24 GHz,the passband range is 22.9GHz-24.9GHz,and the insertion loss in the passband is optimal.At-1.3dB,the return loss is better than 27.7dB,with two transmission zeros appearing at 22.1GHz and 26.6GHz.Branch-matched interdigital center-symmetric filter has a center frequency of 23.5GHz,a passband range of 22.9GHz-24.4GHz,an insertion loss in the passband of-1.6dB,and a return loss better than 10.1dB.Transmission zero at 22.1GHz and 26.1GHz.The center frequency of the patch-matched axisymmetric filter is 24 GHz,the passband range is 22.6GHz-24.9GHz,the insertion loss in the passband is optimally-1.5dB,and the return loss is better than 16.7dB.Two transmission zeros at 21.4GHz and 26.6GHz.Comparing the three designed filters with the band-pass filters proposed in other literatures,it is shown that the proposed three ISGW filters are superior in improving selectivity and reducing external interference.The design flow of ISGW technology combined with microstrip structure design bandpass filter is given.