Design and verification of a two-dimensional wide band phase-gradient meta-surface

For dealing with circularly polarized waves, a high-efficient two-dimensional dispersionless phase-gradient metasurface is devised and achieved by spatially arranging co-polarized reflective metasurface unit cells. The phase of the co-polarized reflection can be freely modulated via a rotating metallic wire of the co-polarized reflective metasurface unit cell in-plane. The achieved phase gradient metasurface can produce opposite-sign phase gradient for left-and righthanded circularly polarized incident waves. During linearly polarized wave incidence, the reflected waves will decompose into two counter-directionally propagating circularly polarized waves. Reflective power density spectra for the linearly polarized wave in normal incidence are simulated, which are well consistent with the theoretically designed anomalous reflection direction. A 2 mm thick sample is fabricated and the mirror reflectivity curve is measured. Experimental results show that for linearly polarized wave normal incidence, the mirror reflectivity is reduced to below -5 dB in a wide band from 9.5 to 17.0 GHz.