Studies On Bending Behaviors Of Electromagnetic Metamaterials And Its Effect On Electromagnetic Properties

Electromagnetic metamaterials,as an artificial composite material,can have extraordinary physical properties through unique design on key physical scales,with excellent designability and broad application prospects,covering many fields such as civil,military and national defense field.As one of the main application forms,electromagnetic metamaterial absorbers are favored because of their advantages of high efficiency absorption and light and thin structure compared with traditional absorbers.The excellent performance of electromagnetic metamaterial absorbers using flexible thin film materials as intermediate media in terms of conformability and tunability makes it a popular research topic.For flexible thin-film materials,bending is the main form of deformation,so studying the effects of bending damage on the electromagnetic properties of thin-film metamaterials has important application value.Firstly,using a flexible material as an intermediate medium,a thin-film electromagnetic metamaterial absorber designed to achieve dual-frequency absorption in the C-band has been designed.The absorber is not sensitive to the polarization mode.It is still relatively sensitive to electromagnetic waves incident obliquely within 30° Ideal absorption effect.By adjusting the size of the resonant unit,the influence of the structure parameters of the resonant unit on the electromagnetic performance is studied.According to the simulation results,the loss mechanism of the electromagnetic energy of the absorber is analyzed from the perspective of electric field strength and surface current distribution.Secondly,on the basis of the metamaterial absorber designed above,the effect of harmonic bending on it was studied.For the overall bending,by calculating the radar scattering cross section of the absorber unit array with different bending degrees in a planar state and comparing it with the metal conductor of the same shape,the impact of bending damage on the electromagnetic performance is characterized,at the resonance frequency point The absorber can effectively reduce the radar cross section.For local bending,the electromagnetic simulation was performed by establishing a multi-period element model in the Miura-Ori folding mode to verify the accuracy of the change in absorption performance when the electromagnetic wave was obliquely incident,and found the instability of the inner ring of the resonant element in the bidirectional folding mode And analyzed the cause of this phenomenon.Finally,the influence of the fracture of the surface metal resonance layer on the performance of the absorber under excessive bending is analyzed,and the electromagnetic properties when cracks are generated in several typical parts are calculated.Based on the analysis method of force electromagnetic coupling,the ability to adjust the tensile strain to the electromagnetic performance was studied.The resonance element of the tunable electromagnetic metamaterial absorber was optimized with prefabricated cracks to improve its safety,and the dielectric constant was considered.Variable materials to improve the tunable range of the absorber,and finally gave a dual-frequency tunable absorber design.