Research And Application Of Substrate Integrated Waveguide Filter With EMSIW

With the development of modern mobile communications,especially in the stage of rapid development of 5G communications,as an extremely important part of the radio frequency system,filters have received more attention in recent years.In the system integration,a large number of miniaturized filters are required to meet the needs of different operating frequency bands.Substrate Integrated Waveguide(SIW)has the advantages of high integration,small size,high Q value,low loss,and good thermal stability.Because of this,it has been widely used in the design of microwave and millimeter wave circuits.In order to better realize the miniaturization of the filter,this article has developed a variety of band-pass filters and duplexers with different structures based on the SIW's multiple division structures and multilayer structures,This design can be applied to 5G communication systems to send and receive signals and the miniaturization of the circuit is realized in the design.The main content of the paper is as follows:1.Two eighth-mode substrate integrated waveguide(EMSIW)resonators and a quartermode substrate integrated waveguide(QMSIW)resonator are conbined to design two singlelayer third-order bandpass filters.Two different cutting methods of QMSIW are adopted to conbine with EMSIW respectively.Based on the structure,the coupling between the source and the load is added to improve the frequency selectivity of the filters.The center frequency of the first filter is around 3.66 GHz,3d B bandwidth is about 450 MHz with 1.36 d B measured insertion loss.The center frequency of the second filter is around 4.93 GHz,3d B bandwidth is about 650 MHz with 1.5 d B measured insertion loss.The return losses are less than-17 d B and-12 d B,respectively.Compared with the traditional full-mode substrate integrated waveguide filter,the sizes of filters are reduced by 83.3%.2.A two-layer fourth-order filter based on eighth-mode substrate integrated waveguide(EMSIW)technology is developed in this part.The filter consists of four EMSIW cavities.The top and bottom EMSIW resonators are coupled through fan windows.The measurement shows that the center frequency of the filter is 3.52 GHz and 3d B bandwidth is 390 MHz.The measured minimum in-band insertion loss is nearly 2.06 d B and passband return loss is better than-10 d B.Compared with the traditional full-mode substrate integrated waveguide filter,the size of the filter is reduced by 87.5%.3.One half-mode substrate integrated waveguide(HMSIW)resonator and two quartermode substrate integrated waveguide(QMSIW)resonators are combined to design two singlelayer third-order bandpass filters.In this part,two different coupling methods are used for coupling between cavities.The center frequency of the first filter is around 9.07 GHz,3d B bandwidth is about 1.15 GHz with 1.5d B measured insertion loss.The center frequency of the second filter is around 11.2 GHz,3d B bandwidth is about 1.37 GHz with 1.4d B measured insertion loss.These two filters are connected with the T-junction of the microstrip line to develop a diplexer.The isolation is better than 30 d B.In both of the passbands,the return losses are less than-12 d B.