X-band Substrate Has An Integrated Waveguide Fin-coupled Filter

Rapidly advancing with the advancement of modern communication technology,the components of the communication system have advanced significantly,with microwave filter,a critical component,not far behind.The momentum of its development is swift.As a frequency division component in the communication system,microwave filter is especially essential for enhancing its performance,as its performance directly impacts the quality of the entire system.The utilization of Substrate Integrated Waveguide(SIW)as a transmission line in filter design has seen a surge in recent years due to its superior rectangular waveguide performance and minuscule microstrip line size.This is evidenced by its numerous benefits,such as a high Q value,minimal loss,and ease of integration with planar surfaces.In order to improve the performance of the microstrip filter,without increasing the cavity length,it is necessary to improve the rectangular ratio of the existing filter,and in order to obtain better standing waves and smaller insertion loss,the selection of the double-layer SIW coupling structure is put forward new requirements.In order for the filter to be more selective,a suitable coupling structure needs to be matched.In this context,the third chapter of this thesis mainly mentions three newly designed coupling structures: fin line,Archimedean spiral coupling structure,and non-integer dimension superstructure.Compared with the traditional rectangular bar,round hole and other coupling structures,these three coupling structures themselves have a certain filtering effect in the resonant cavity,and only need to occupy the area of a resonator to achieve better filtering effect,with the advantages of small size and easy to realize device type.On this basis,they are combined with traditional generalized Chebyshev filters to further improve the selectivity of the filters.Firstly,the X-band SIW transmission line is designed,and the simulation results are as follows: in the entire X-band range,S11 <-45 d B,S21 >-0.0585 d B,the transmission performance is good,and the successful design of this transmission line lays a solid foundation for the subsequent design of the filter.In addition,in order to konw more coupling effect between coupling structures and the influence of coupling structures on filter performance,and in order to better promote the design and development of filters,this thesis proposes three coupling structures.Secondly,according to the generalized Chebyshev filter function and topology,this thesis uses the designed coupling structure to design the filter,and realizes the X-band SIW fin-coupled filter and Archimedean helix-coupled filter with SIW.However,due to the structure of the fin wire itself,the design results can not reach the ideal indicators,so the subsequent hybrid coupling method is used,the design is the Archimedes spiral coupling filter,the final design results of the main parameters are: center frequency f＿0 =9.5GHz,bandwidth BW = 190 MHz,standing wave S＿{11}=-21.3d B,insertion loss S＿{21}=-1.9d B,out-of-band rejection higher than 30 d B,relative bandwidth of 2%,Rectangle ratio 2.3.The overall size of the whole device is 53.91*24.83*1.076 mm.Finally,X-band SIW Archimedes helix and fin and Archimedean spiral and noninteger dimension superstructure hybrid coupling filters are designed,mixed-coupled filter out-of-band rejection can be better than-35 dB.