Research On Wave Absorber Based On Metamaterial And Its Application In Antenna

Metamaterial is an artificial electromagnetic material composed of subwavelength periodic array structure.Through reasonable design of the geometric structure,size and other parameters of metamaterial,the equivalent dielectric constant ε(ω)and equivalent permeability μ(ω)can be effectively regulated,so as to achieve the absorption of incident electromagnetic wave.Based on the characteristics of metamaterial,a broadband absorber is designed and its absorbing mechanism is discussed.At the same time,the cross polarization of the original antenna is reduced by integrating the absorber with the antenna.The main contents are as follows:(1)Terahertz and infrared wideband absorber based on metamaterials.For the terahertz broadband absorber,firstly,a plurality of perfect absorption units with similar absorption peak frequencies are designed,and then these units with different absorption frequencies are arranged in a certain way to form a 5×5 array,so as to realize broadband absorption by means of multiple absorption peaks superimposed.The simulation results show that the proposed terahertz absorber can achieve more than 90%absorption in the 0.88-1.08 THz band,and the relative bandwidth is about 20%,which meets the requirements of broadband absorption.The central frequency of the absorption band is 0.99 THz,and the structure has the characteristics of low profile.For the infrared wideband absorber,based on the three-layer structure of "metal-media-metal",the absorption rate reaches more than 90% in the band range of10-12.7THz,and the relative bandwidth reaches 23%,realizing the wideband absorption.Moreover,the structure has the same absorption effect on TE incident wave and TM incident wave,that is,the absorber is not sensitive to the polarization mode of incident wave.In addition,the absorber also has the advantages of simple structure and easy processing.(2)Application of broadband microwave absorber in antenna based on metamaterial.Firstly,a polarization-sensitive electromagnetic absorber based on metamaterial is designed.For vertically polarized incident waves,the absorber can achieve more than 90%broadband absorption in the 6.4-13.3GHz frequency band,and the relative bandwidth is60%.The absorptivity of the incident wave with horizontal polarization is approximately 0.Secondly,a high-end port isolation dual polarization antenna is designed.The horizontal port isolation and vertical port isolation of the designed dual polarized antenna are both below-30 d B.When the horizontal port is fed,the main polarization gain of the antenna reaches 7.7d Bi,and the cross polarization of the antenna E plane is below-10 d B.The cross polarization of H-plane is below-28 d B;When the vertical port is fed,the main polarization gain of the antenna reaches 7.7d Bi,and the cross polarization of the antenna E plane is below-18 d B.The cross polarization of H-plane of the antenna is below-15 d B.Then,the designed microwave absorber is integrated with the antenna.The simulation results show that the working bandwidth of the integrated antenna is expanded,and the port isolation is all below-30 d B.When the horizontal port is fed,the main polarization wave of the integrated antenna is not affected,the cross polarization of E-plane is almost unchanged,and the cross polarization of H-plane decreases about 10-15 d B in the radiation direction of the antenna.When the vertical port is fed,the cross-polarized wave radiated by the integrated antenna is absorbed by the absorber.Obviously,after the integration of the absorber and antenna,the cross-polarization of the original antenna is reduced on the premise that the performance of the main polarized wave is almost not affected.Finally,the designed device is processed and measured.Through comparison,it is found that the measured results are basically consistent with the simulation results,which better verifies the performance of the designed device.