Guided-Wave-Excited Binary Huygens’ Metasurfaces for Dynamic Radiated-Beam Shaping with Independent Gain and Scan-Angle Control

This paper presents a reconfigurable metasurface that is able to dynamically and independently control the gain and propagation direction of the radiated field, with reduced biasing complexity and power consumption at a low profile. Moreover, the proposed metasurface is guided-wave fed thus leading to a compact tunable leaky-waveguide structure. Heretofore, reported reconfigurable metasurfaces have mainly demonstrated dynamic tailoring of free-space waves by redistributing their reflection or transmission phase profiles at a fixed amplitude. In contrast, we demonstrate dynamic transformation of a guided wave into an aperture field with controlled amplitude such that the gain and scan angle of the corresponding radiated field are dynamically and independently controlled. In particular, the aperture field is digitally synthesized by the proposed tunable Huygens’ metasurface whose local transmission coefficient is able to be dynamically tuned as two digital bits of $-|T_o|$ and $+|T_o|$, where $T_o$ represents a user-defined constant. This digital synthesis and the deliberate utilization of a nonbianisotropic type Huygens’ metasurface simplify biasing requirements, and make the proposed design more feasible. Through simulations and experiments, we show dynamic steering of a beam from $-{40}^{\circ }$ to $+{40}^{\circ }$, and two broadside radiations with different radiation gains at a fixed operating frequency of 5 GHz.