| Metamaterial is a kind of artificial composite material whose unit size is periodic arrangement of sub-wavelength structure.Its characteristic is that by rationally designing the shape and structure of the metamaterial unit,rationally optimizing the size parameters of the unit,and rationally arranging the arrangement of the unit,the physical properties that are not available in the existing materials in nature can be obtained.These physical properties are especially concentrated in electromagnetic properties,such as negative permeability,negative permittivity,negative refractive index,and Anticherenkov radiation.People can customize the electromagnetic wave through the rational design of the metamaterial unit structure according to the required electromagnetic characteristics and from the perspective of reverse thinking.Metamaterial absorbers have the characteristics of high absorption rate,thin thickness and light weight,and are widely used in electromagnetic shielding,stealth,microwave and radio frequency energy harvesting,solar cells and other fields.To solve the problems of low absorption rate,narrow absorption frequency band,and inability to conform to curved surfaces of existing metamaterial absorbers.In this paper,starting from the absorption mechanism of metamaterial absorbers,the principle of absorption based on impedance matching principle,equivalent circuit model,and interference theory is studied.The ultra-wideband flexible absorber based on multi-layer integrated structure and the transparent ultra-wideband flexible absorber based on indium tin oxide ITO film are designed respectively.The main content includes the following three aspects:(1)A multi-layer integrated structure metamaterial absorber composed of a top square ring array resonant structure layer,a middle metal plate-polymer interlayer,and a bottom continuous metal ground layer vertically stacked.The designed multi-layer integrated absorber has an absorption rate of over 85% in the wide frequency range of 7.8?10.3GHz,and has high absorption performance under the conditions of different polarization angles and incident angles.In addition,multi-physics analysis of surface electric field,surface current,and surface heat distribution has also verified the electromagnetic energy-thermal energy conversion of the metamaterial absorber.(2)An ultra-wideband optically transparent metamaterial absorber using a square ring and a cross-shaped composite resonance mechanism composed of a transparent indium tin oxide(ITO)resistive film is proposed.The designed transparent absorber has an absorption rate of over 90% in the ultra-broadband range of 8-30.3 GHz,and the average optical transmittance of the entire structure in the visible light range exceeds 78%.And it has the absorption characteristics of insensitive to polarization and wide angle of incidence.In addition,by replacing the intermediate air gap with polydimethylsiloxane(PDMS)and polymethylmethacrylate(PMMA)media,the transparent metamaterial absorbers that can be used for stealth weapon conformal applications and rigid window glass are designed.The wideband absorption mechanism of metamaterial absorber is also verified by analysis of surface electric field and surface current distribution.(3)Using high-density interconnection(HDI)technology and micro-electromechanical system(MEMS)technology to fabricate two kinds of ultra-wideband flexible absorber samples,and test the absorption rate of the two kinds of absorbers samples in the free space method test system.The test results show that the measured results of the processed absorbers are consistent with the simulation results. |
PDF Full Text Request