Research On Broadband Transparent And High-efficiency Absorber Based On Metamaterial

Electromagnetic absorbing materials refer to materials that can attenuate and absorb incident electromagnetic wave energy,and are an important research direction from the intersection of two important fields of modern information communication and materi-als.In order to solve the application problem of absorbing materials in aircraft cockpit glass,ship portholes,radio frequency identification systems and other scenarios that re-quire transparency,absorbing materials need to have good visible light transparency char-acteristics.Through investigation,it is found that the current researchers have proposed that the absorption intensity of incident electromagnetic wave energy by the proposed ab-sorbing material is 90%,and with the advancement of radar detection technology,this absorption intensity may not be able to meet the application fields such as information hiding.Therefore,the research focus of this thesis is to study the balance compatibil-ity between the two requirements of high-efficiency transparent absorbing materials with higher absorption strength（99%,99.8%）and wide absorption frequency bands.The spe-cific work is as follows :First,this study proposes a planar periodic broadband high-efficiency transparent absorbing material,which combines lead tin oxide（ITO）on top of polyethylene tereph-thalate（PET）material.The transparent conductive film is etched into a metamaterial structure as the conductive impedance layer on the top layer,air as the intermediate di-electric layer,and a continuous ITO conductive film as the bottom floor layer.In order to achieve the perfect match between the absorbing material and the free space,and com-plete the high-intensity absorption of incident electromagnetic wave energy,this research utilizes the compactness of the hexagonal periodic structure to design a hexagonal ring high-efficiency absorbing material.In order to expand the absorption bandwidth of the absorbing material and solve the problem that the high-efficiency absorbing bandwidth is too narrow,this study introduces an additional resonance unit based on the hexagonal ring structure to realize the combination of resonance and expand the resonance bandwidth.Practical applications require certain physical properties.In this study,a wave absorb-ing material using transparent polymethyl methacrylate（PMMA）as the dielectric layer was proposed.In this study,the designed air-dielectric broadband high-efficiency trans-parent absorbing material was processed.After actual measurement,its high-efficiency absorption（absorption intensity 99.8%）bandwidth reached 39%.Secondly,this study proposes a three-dimensional periodic broadband high-efficiency transparent absorbing material.The PET-ITO transparent conductive film is etched into a metamaterial structure.The conductive impedance layer of the material is placed up-right on the bottom transparent floor layer film.In this study,the three-dimensional periodic structure can achieve two-dimensional absorption of incident electromagnetic waves,and design a three-dimensional double-split ring broadband high-efficiency trans-parent absorbing material.In order to further enhance the absorption strength of the ab-sorbing material,the structure is optimized in this study,and the ring combination unit is designed to increase the absorption strength of the material.In addition,consider-ing the polarization characteristics of the material,this study proposes a polarization-insensitive broadband high-efficiency absorber with a centrosymmetric design.Finally,the designed single-polarization broadband high-efficiency transparent absorbing mate-rial was processed in this study,and its high-efficiency absorption（absorption intensity99.8%）bandwidth reached 31% after actual measurement.Finally,this research proposes a non-uniform period broadband high-efficiency trans-parent wave absorbing material.The PET-ITO transparent conductive film is etched into a non-uniform period metamaterial structure as the conductive impedance layer of the mate-rial,the middle layer uses air as the medium,and the bottom layer uses air as the medium.The floor layer is a continuous ITO transparent conductive film.This study utilizes the perfect matching mechanism to design strip-shaped high-efficiency absorbing materials with high absorption strength.In order to further expand the high-efficiency absorption bandwidth,a non-uniform periodic structure was introduced in this study,and a broadband high-efficiency transparent absorbing material with a strip-shaped non-uniform periodic structure was designed.The simulation results show that its high-efficiency absorption（absorption intensity of 99.8%）has a bandwidth of 36%.BeIn conclusion,the three design schemes proposed in this study realize the design of broadband high-efficiency transparent absorbing materials in different ways.The pro-posed design provides an idea for the compatibility design of the absorption strength en-hancement and absorption bandwidth expansion of the absorbing material,and has broad application prospects in the fields of military information hiding and civil electromagnetic compatibility.