An Ultra-Wideband Reflective Phase Gradient Metasurface Using Pancharatnam-Berry Phase

Abstract

Designing a transmissive and reflective phase gradient metasurface (PGM) using Pancharatnam-Berry (PB) geometrical phase must be based on an appropriate metasurface, which can realize circular-polarization (CP)-conversion transmission and CP-maintaining reflection, respectively. When an appropriate metasurface is proposed, a PGM can be easily constructed by gradually rotating the anisotropic or chiral resonators in different unit cells. In this paper, to design an ultra-wideband reflective PGM, first, an ultra-wideband CP-maintaining metasurface is proposed, and the numerical simulation results show that the proposed metasurface can realize CP-maintaining reflection at CP incidence between 8.43 and 26.93 GHz; in addition, a PB phase will be generated in its co-polarized reflection coefficient by rotating the anisotropic resonators in its unit cells. Thus, based on the metasurface, an ultra-wideband PGM is constructed successfully, the simulated and experimental results show that the PGM can realize ultra-wideband anomalous reflection at arbitrarily polarized incidence, and almost all the reflected waves at right-handed and left-handed CP (RHCP and LHCP) incidences will both be deflected to an anomalous direction; in addition, the reflected waves at linear and elliptical polarized (LP and EP) incidences will be separated into two beams for the LP and EP waves that can both be decomposed into a pair of RHCP and LHCP waves. Furthermore, finally, a detailed theoretical analysis is presented for the CP-maintaining reflection of the proposed metasurface.