Design And Application Of Broadband Polarization Conversion MetaSurface

Polarization conversion metasurface is an important branch of electromagnetic metamaterials,which can control the polarization state of electromagnetic waves and plays a crucial role in communication,radar,antenna,and optics fields.To address the issues of narrow polarization conversion bandwidth and low transmission efficiency in current polarization conversion metasurfaces,this article conducts the following research:Firstly,a reflection-type polarization conversion metasurface structure based on elliptical aperture rings and intermediate metal strips is proposed,which utilizes the resonances generated by the two patterns to induce electromagnetic coupling effect and achieves efficient reflection cross-polarization conversion in the frequency range of 10.4～3 6.5 GHz,covering the Ku and K bands,with a relative bandwidth of 111%.The variation of polarization conversion performance with structural parameters and incident angle is studied,and the polarization conversion mechanism is analyzed using surface current analysis.Secondly,a reflection-type polarization conversion metasurface structure based on mirrored double "C" shaped aperture rings is proposed,achieving polarization conversion performance of linear to left-handed circular polarization with axial ratio less than 3dB in the frequency range of 10～26.5 GHz,covering the Ku and K bands,with a relative bandwidth of 90%.This structure has great potential for integration into antenna systems.Thirdly,based on the polarization conversion metasurface unit structures designed above,a mirrored array structure based on reflection-type line-line polarization conversion metasurface unit is proposed,which utilizes the interference and cancellation of electromagnetic waves generated by two mirrored metasurfaces to achieve radar cross section reduction.Simulation results show that the mirrored array structure achieves a-1OdB reduction bandwidth in the frequency range of 10～19.8GHz,23～25.5 GHz,and 28.2～36.7 GHz,corresponding to the efficient polarization conversion frequency band of the designed structure,with a relative bandwidth of 102%.Fourthly,a’ transmission-type polarization conversion metasurface structure based on inward bent "H" shaped aperture rings is proposed.By selecting the polarization wave direction with metal gratings and the polarization wave rotation characteristics with anisotropic structures,transmission cross-polarization conversion is achieved in the frequency range of 6.2～23.2 GHz,covering the X and Ku bands,with a high relative bandwidth of 115%.Due to its asymmetric transmission characteristics,this structure has good application prospects in antenna covers.In conclusion,this article provides an in-depth analysis and discussion of the polarization conversion performance and mechanism of reflection-type and transmission-type polarization conversion metasurfaces,explores their applications in electromagnetic scattering field,and verifies the simulation results through experiments,providing ideas for the design of broadband,efficient polarization conversion metasurfaces and their related applications.