Dual-Polarized Reconfigurable Metasurface for Multifunctional Control of Electromagnetic Waves

This article presents a reconfigurable multifunctional metasurface (RMM) with independent control of orthogonally polarized waves. Each meta-atom of RMM has four varactor diodes (two sets of orthogonal parallel diodes) connected and voltage biased. The voltage difference of the two sets of parallel varactor diodes is a constant. Thus, the orthogonally polarized reflected wave can be tuned independently. Unlike in other reported voltage-controlled RMMs, in the developed RMM, biasing voltages can be applied in one direction only. A tunable range from 7.2 to 7.8 GHz can be achieved. Two functionalities of the proposed RMM, namely, beam steering and polarization conversion, are demonstrated numerically and experimentally. Beam steering can be independently achieved in the ${x}-/y$ -directions when the incident plane wave is an $x-/y$ -polarized plane wave. For an arbitrary linear polarized incident plane wave, the decomposed orthogonally polarized waves can also be reflected toward two predefined directions based on the dual-polarized independent tunability of the proposed design. As for polarization conversion, the reflected waves can be flexibly switched among linear-to-orthogonal (LP-to-XP), linear-to-circular, and linear-to-elliptical polarizations in the operating frequencies depending on the phase requirement. The polarization conversion ratio is up to 90% for LP-to-XP polarization and the axial ratio is smaller than 3 dB for linear-to-circular polarizations.