Research Of Stealth Technology Based On Matematerial

As an artificial composite structured material,metamaterial demonstrates a plenty of unique properties that are hard to found in nature,with powerful manipulations of different physical fields in the acoustic,electromagnetic and optical domains.It shows great potentials in applications like electromagnetic stealth and multiphysical control,and receives extensive attentions within the scientific community.This thesis is focused into these two areas,and the main contents and contributions are listed below:1)A transparent metamaterial absorber with large light transparency and prominent microwave absorption is proposed based on the transparent semiconductor indium tin oxide(ITO).The absorption bandwidth can be expanded by appropriately adjusting the resonance positions of the structure.The light transmittance of the overall structure is 77%.To create a conformal transparent coating,a flexible millimeter wave metamaterial absorber is designed and fabricated.After the optimization of the reflection response of the meta-atoms under oblique incidence,stable and excellent absorption is maintained within the Ku band when the incident angle changes from 0° to 60°,leading to great suppression of backscattering when a metal cylinder is covered with this material.In order to optimize the absorption performance of metamaterials,a broadband transparent metamaterial with the QR code shaped pattern is design on the basis of joint optimization with the tools of Matlab and CST.In addition to the absorption type metamaterial,a broadband low-scattering transparent stealth metamaterial is proposed and experimentally verified.Analogous to the optically rough surface,the designed metamaterial can disperse the reflected energy in various directions of the upper space,with the 10 dB RCS reduction bandwidth ranging from 7GHz to 14 GHz.2)In order to overcome the incompatibility between infrared stealth and radar stealth,a lossy patch array is proposed with large metallic coverage and improved impedance matching,giving rise to the merits like low infrared emissivity,wideband microwave absorption,small thickness and light weight simultaneously.Furthermore,based on the idea of diffuse scattering,an infrared/radar compatible stealth metamaterial is designed and fabricated.The diffuse reflection and low infrared emission are obtained at the same time by arranging two coding elements with low-infrared emissivity,equal reflection amplitude but opposite phase in the microwave region.The infrared emissivity of the fabricated sample is less than 0.2,and the 10 dB RCS reduction bandwidth is 8 to 18 GHz.3)Based on the membrane-type structures,a multi-physical metamaterial with simultaneous sound insulation and low electromagnetic scattering is proposed and experimentally validated.When a thin PET membrane is coated by the conductive ITO film on which the lossy meta-patterns are etched by lithography,both the electromagnetic and sound responses can be created a the same time.It achieves excellent sound insulation performance from 1100 Hz to 1370 Hz,and the backward RCS is reduced by more than 10 dB in X band.Furthermore,a membrane-type metamaterial is further developed to realize the sound insulation and anisotropic electromagnetic manipulation simultaneously,which can respond in a distinct way to different polarization components.4)Since the aforementioned multiphysical metamaterial cannot achieve independent manipulation of sound wave and electromagnetic wave,a new type of metamaterial is proposed to overcome this limitation,as is made of four basic coding units with simultaneous phase responses to both acoustic and electromagnetic waves.By carefully choosing the coding sequences,we can adjust the sound wave and electromagnetic waves separately and simultaneously,offering a promising route for multiphysical control in the future.