| Metamaterials,as special materials and devices with artificial structures,have attracted extensive attention from researchers for their miraculous physical properties and artificial tunability of electromagnetic parameters.Electromagnetic waveabsorbing devices based on the design concept of metamaterials have also been fully developed,and have broad application scenarios in the fields of electromagnetic stealth and energy harvesting.In addition,in the electromagnetic spectrum,from microwaves to visible light and even ultraviolet band,metamaterial absorbers have their unique construction methods and functional characteristics.Starting from the development,theory and application of electromagnetic metamaterial based wave absorbing devices,this article describes the related concepts of electromagnetic metamaterial absorbers in detail,as well as the development process and current status of metamaterial absorbers working in the microwave and visible near-infrared spectrum range,at the same time,the relevant theories of metamaterial absorbers are properly analyzed.In addition,in response to the needs of absorbers with more types and better properties,four absorbers with different performances are proposed.Aiming at the collection of solar energy and light energy from visible light to nearinfrared,a wideband absorber working in the wavelength range of 400-1600 nm is proposed,through the simulation calculation of FDTD,it has an average absorption of97.2% in the working band.Physical excitation phenomena such as surface plasmon,Mie resonance,electric dipole resonance and cavity resonance are the main causes of absorption.Meanwhile,the sudden change of absorptivity based on Rayleigh-Wood anomaly is also analyzed quantitatively.The absorber has good polarization insensitivity and angle stability,and the influence of some dimension parameters on the absorption is analyzed from the perspective of absorption mechanism.A wideband transparent absorber working in microwave band is proposed,which is mainly based on ITO film with micro structure,in the frequency range of 6.93-16.68 GHz,it has an absorption of more than 97%.Since the materials that make up the metamaterial absorber are flexible and transparent,the wave absorber has conformality,can be arranged on a surface with a certain curvature,and has a certain degree of optical transparency.The wave absorber also has good polarization characteristics and oblique incidence characteristics,and the conductive film made of ITO and its artificially designed unit microstructure are the main part of the absorbing effect and energy loss.Finally,the processing and preparation of samples are completed by stacking ITO-PET films and PVC flexible plates layer by layer.The reflectance of metamaterial samples is measured by arch method,and the transmittance of metamaterial samples is measured by free space method.For the currently popular metal-dielectric structure microwave absorber,two different absorber structures are designed,they are a three-band absorber based on the metal-dielectric-metal classic structure,and a multi-band absorber based on copperFR4 copper clad laminate multilayer stacking.At the same time,spectral analysis,multi-peak source analysis,angle performance analysis,electromagnetic field and surface current analysis,and size parameter analysis were carried out on them respectively.For the three-band absorber,the sample processing is carried out by standard PCB processing technology,and for the multi-band absorber with multi-layer stacking,the sample is realized by CNC milling single-layer copper clad laminate and stacking layer by layer.Finally,the absorption performance is tested by the arch method experiment. |
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