Reconfigurable Omni-Metasurface for Single-Beam Steering Based on Simultaneous Transmission–Reflection Continuous Pre-Phase Technique

This article proposes an omnidirectional metasurface capable of simultaneous transmission–reflection and continuous pre-phase control for low sidelobe level (SLL) bidirectional single-beam scanning under plane-wave incidence from both <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\pm z$ </tex-math></inline-formula>-directions. We present a continuous pre-phase technique to suppress SLLs in a 1-bit phase-only controlled metasurface. Unlike present algorithm-optimized pre-phase distributions, this method significantly reduces computational complexity and reduces coupling from metasurface discontinuities while maintaining a lower SLL. Subsequently, we derive the transmission and reflection Jones matrices for two distinct types of circularly polarized (CP) bidirectional unit cell. The derived matrix results demonstrate that the electrical phase and the geometric rotational phases can be decoupled by appropriately rotating the upper and lower structures, demonstrating the effectiveness and practicality of continuous pre-phase control in the proposed bidirectional metasurface. Moreover, by integrating two positive–intrinsic–negative (p-i-n) diodes, the proposed metasurface enables 1-bit phase electrical control of both reflected and transmitted waves. To verify the approach, we designed, fabricated, and measured a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$12\times 12$ </tex-math></inline-formula> element array. The experimental results confirm that under plane-wave illumination from <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\pm z$ </tex-math></inline-formula>-directions, both transmitted and reflected waves successfully achieve single-beam scanning from 0° to 45° with consistently low SLL.