Dual-Band Nonlocal Reconfigurable Intelligent Surfaces for Precise Full Half-Space Beam Shaping

초록

This paper presents the synthesis, design, and experimental verification of a nonlocal, dual-band reconfigurable intelligent surface (RIS) capable of generating arbitrary radiation patterns over the full half-space at 4.0 GHz and 6.3 GHz. The proposed RIS consists of dual-band unit cells, each comprising a pair of interleaved sub-cells engineered to operate independently at their respective target frequencies. This hardware-level band decoupling enables the nonlocal synthesis based on microwave network theory to be applied independently at each frequency, thereby allowing efficient optimization of the RIS impedance distribution for complex wavefront transformations. Based on this framework, various full half-space radiation patterns—including single-beam steering, dual-beam generation, and sector-pattern synthesis—are independently synthesized at each of the two operating frequencies. These patterns are numerically and experimentally validated using an RIS prototype consisting of 14 × 14 varactor-loaded unit cells. The measured radiation patterns show good agreement with the predicted responses, highlighting the potential of the proposed RIS as a versatile wave-control platform for next-generation smart radio environments. © 1963-2012 IEEE.

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