Design Of Microstrip Filter Based On Composite Right/Left Handed Metamaterial

The rapid development of Internet of things communication puts forward higher requirements for radio frequency system.The performance of filter with frequency selection function directly determines the transmission quality of communication system.In recent years,RF system has put forward higher requirements for the performance of filter such as easy integration,miniaturization,low insertion loss,high selectivity and wide stopband.As a new type of artificial material,electromagnetic metamaterial is widely applied in the design process of RF microwave devices because of its unique singular characteristics.In the design process of microwave devices,the classical transmission line form of composite right/left handed transmission line(CRLH TL)has the advantages of miniaturization and new structure.Basing on the theoretical basis of CRLH metamaterials,two miniaturized and high-performance composite right/left handed transmission line microstrip filters are designed in this paper.The work of this paper is mainly divided into the following sections:1.Based on the non-resonant CRLH TL resonant unit proposed in this paper,a single-pass bandpass filter with miniaturization,low insertion loss,and high selectivity is designed to work in the L-band by using coupling with C-type transmission lines.Firstly,by analyzing the zero-order and negative-order resonant modes of CRLH TL,extracting equivalent circuit,the filter structure parameter model is obtained and simulated.Then,the broadband characteristics are improved.By analyzing the attenuation characteristics of CSRR DGS,which is loaded into the filter to achieve broadband.The simulation results show that the filter has the characteristics of miniaturization,low insertion loss,high selectivity and wide stopband.2.Basing on the novel CSRR proposed in this paper,it is loaded into SIW and a resonant CRLH TL dual-band bandpass filter is designed,which works in WLAN.The filter structure model is constructed by analyzing the SIW theory and the new CSRR structure.Firstly,a single passband filter is designed,which acts at 5.1 GHz;Then,on the basis of single-band filter structure,the same new CSRR is loaded.By analyzing the influence of structure parameters on transmission characteristics,a dual-band filter with resonant frequency of 2.45 GHz and 5.2 GHz is finally designed.3.Inversing the extracted equivalent parameters by Matlab software combining with S parameters to verify that the non-resonant and harmonious mode CRLH TL filter design has the left and right hand transmission characteristics of electromagnetic metamaterials in a specific frequency band,which fully demonstrates the correctness of the design of CRLH TL microstrip filter.Then,two CRLH TL filters are compared with other similar filters to show the advantages of the filter design in this paper.4.Physical processing and testing.The test results of the two filters are in good agreement with the simulation results.It is verified again that the non-resonant CRLH TL single-band filter design has the characteristics of miniaturization,low insertion loss,high selectivity and wide stopband,and acts in the L-band.The resonant CRLH TL dual-band filter has the characteristics of miniaturization and high selectivity,which acts on WLAN.In this paper,the filter designed has certain engineering application value.