Dynamic phase gradient synthesis with a moiré metasurface and its application in microwave beam manipulations.

In this Letter, we theoretically explore the potential of a moiré metasurface that achieves dynamic synthesis of phase gradients via dislocation. Our moiré metasurface consists of two cascaded metasurface layers encoded with spatially conjugate quadratic phase profiles, and linear phase modulation carrying a synthesized phase gradient can be constructed as the phase moiré pattern formed by two overlapped phase layers. As a proof of concept, a moiré metasurface operating at a center frequency of 2.5 GHz is designed and theoretically investigated. The numerical results show that the synthesized phase gradient yields a beam deflection of up to ±54° (a total coverage of 108°), demonstrating continuous spatial beam steering capability via tunable dislocations among the metasurface layers. Our work reveals that the phase gradient synthesis strategy empowered by the moiré effect would provide an alternative for low-cost microwave beamforming systems, which potentially facilitates radar techniques and wireless communications.