Design,Fabrication And Properties Of AFSIW Filter Based On LTCC Technology

With the development of the 5th generation mobile networks?5G?,the internet of things?Io T?and artificial intelligence?AI?,the demand of miniaturized,highly integrated and high-frequency electronic components are becoming more and more urgent.The circuits and components based on substrate integrated waveguide?SIW?structure are the hotspots in the research field of microwave and millimeter wave systems.Filters have been widely studied as essential key components in electronic communication systems.Traditional microstrip-line filters could not meet the requirements of high Q and low insertion loss in millimeter wave systems.The previous studies shown that the SIW filters made by LTCC technology had obvious advantages,such as small device volume,easy processing,and flexible in design and manufacturing structure.They can not only improve performance of filter,but also achieve miniaturization.The main content of this thesis is to design and fabricate the SIW filter based on LTCC technology.The main works of this thesis are as follows:?1?The working principle,design and preparation method of the SIW filter were introduced.The classical method and group delay simulation method were tried and discussed.In the subsequent filter simulation process,the advantages of the two methods were applied,which accelerate the simulation and design process of filter structure.?2?A 26 GHz SIW filter was designed by combining electromagnetic field simulation and circuit simulation.The influence of material performance,filter structure and other parameters on the SIW filter performance was analyzed.A structure with via grounding was proposed to make the port structure more suitable for actual testing.The center frequency of the designed SIW filter is 26.4 GHz,the relative bandwidth is 14.5%,the minimum insertion loss is 0.68 dB,and the return loss S₁₁is less than 17 dB in the band.The fabrication process of the SIW filter based on LTCC were further optimized in combination with the characteristics of independent LTCC materials and preparation process.The test results show that the measured results are in good agreement with the simulation.?3?In order to improve the performance of the SIW filter and reduce the filter size,the SIW filter embedded with air-cavity structure were designed and analyzed.The effect of location,size and numbers of the air-cavity on the filter performance were studied.A third-order air-filled SIW?AFSIW?filter was designed with a center frequency of filter is 26.3 GHz,a insertion loss of 0.51 dB and a relative bandwidth of16.4%.Compared with the above SIW filter,the volume of the AFSIW filter is only increased about 30%.?4?A modified process by screen printing on the back of the LTCC green tape was used to achieve high quality via filling.The LTCC embedded air-cavity structure was constructed through a special lamination process without the addition of the sacrificial materials.The center frequency of the obtained AFSIW filter sample was26.3 GHz.The minimum insertion loss and the relative bandwidth are 0.66 dB and16.3%,respectively.The return loss in-band is better than 18 dB.The measured results of the obtained sample are in good agreement with the simulation results,which proves that the insertion of air-cavity in the SIW filter could improve the transmission performance of the filter and control the volume of the filter.