Multifunction Cross Polarization Converter Based on Ultra-Thin Transmissive Chiral Metasurface in C and X Bands

Polarization is an essential feature of electromagnetic (EM) waves, and the variety and simplicity of polarization conversion have substantial demands in wireless systems. Metasurfaces, two-dimensional artificial electromagnetic structures, are emerging as novel modulation solutions for EM waves. In this work, a multifunction polarization converter based on a transmissive metasurface (MPC-TMS) is suggested. This planar structure is made up of a copper-clad dielectric substrate with top and bottom orthogonal slotted sheets joined by a metal via. With frequency selectivity, x- and y-linear cross-polarization transformations are efficiently achieved between 8.04-8.82 GHz (9.25%) and 7.04-9.07 GHz (25.19%), respectively. Meanwhile, the presented microstructure is capable of rotating a circularly polarized incident wave into its opposite handedness from 8.16 to 8.87 GHz (8.46%). Both peak transmission efficiency and the polarization conversion ratio exceed 0.95 simultaneously. In addition, resonance superposition and coupling effects are investigated to explain the operating mechanism. This microstructure not only has a simple construction with an ultra-thin thickness (0.06 lambda), but also reveals superiorities in bandwidth, transmission, and efficiency. To verify the above quadruple polarization conversion, measurement has been implemented, and the results are reasonably accordant with simulation, suggesting that the low-profile converter is conducive to future telecommunication design where polarization diversity is needed.