Investigation And Design On High Performance Planner Integrated Band-pass Filters

As a key component in modern wireless communication systems,microwave filter will directly influence the quality of the entire system.With the rapid development of wireless communications and system in package,there are more and more urgent demands on the high performance of filter in the microwave and millimeter wave system.Therefore,it is necessary to design filters with high integration,high performance,and miniaturized size.Employing the two-mode technology and controllable mixed electric and magnetic coupling for the substrate integrated waveguide(SIW)resonators,a novel dual-mode substrate integrated waveguide band-pass filter and a type of quasi-elliptic filter with controllable electric and magnetic mixed coupling are investigated respectively.Experimental study on each research topic was also carried out to verify the design methodology.The dissertation is organized as follows:The introduction briefly describes the background and significance of the related field at first.And then,the paper summarizes the current research status of SIW based on related literatures.Next,the main contents of the dissertation are summarized.Chapter two introduces the theoretical framework of filters.From different perspectives,this chapter focuses on the classification of filters,which describes the concepts theory and the related technical indicators of filters.Then several types of the normalized low-pass filter prototype are analyzed,including Butterworth low-pass filters,Chebyshev low-pass filters and Quasi-elliptic low-pass filters.The conversion of low-pass prototype to band-pass is provided in the end.Chapter three proposes a novel dual-mode substrate integrated waveguide band-pass filter.The return loss of this filter is better than 20 dB at the center frequency of 11.33 GHz and the insertion loss in pass-band is less than 1.2 dB.Two transmission zeros are obtained at the both below and above sides of the pass-band.To validating the filter design,a filter example is fabricated utilizing a single layer PCB process.Good agreements are obtained between the measured and simulated results.The Measured results show that the size of designed filter is reduced,and make a better development on the attenuation on both sides of the pass band.In addition,the filter show the advantages of the reduce radiation loss,easy miniaturization,good frequency selectivity,and so on.Chapter four presents a novel substrate integrated waveguide(SIW)band-pass filterwith controllable electric and magnetic mixed coupling to obtain additional transmission zeroes based on SIW cavity resonators using one-layer PCB process.Mixed coupling is achieved by etching three symmetrical slots on the top surface and introducing an iris-window between two SIW cavities.Coupling coefficient can be controlled by adjusting the dimensions of the slots and width of the iris-window.Three-order directly coupled quasi-elliptic filters is designed,simulated and fabricated using the mixed electric and magnetic coupling second-order filtering units at C-band.Simulations and measurements verify the design idea and the proposed filter show the advantages of low insertion,good selectivity with controlled transmission zeros,wide upper stop-band,and easy integration with other planar.