Transmissive Programmable Metasurface Based on Multimode Resonance With a Single Liquid Crystal Layer

To address the limitations of liquid crystal (LC)-based transmissive programmable metasurfaces in the microwave bands—specifically restricted phase tuning ranges and excessive LC layer thicknesses—this work proposes a novel via-free transmissive LC unit cell and metasurface design based on multimode resonance theory (MRT). By integrating four scaled LC resonant structures within a single unit-cell plane, the design leverages multimodal coupling to achieve a continuous transmissive phase shift exceeding 360◦ with an LC layer of only 9 μm, effectively overcoming the phase-range deficiency inherent in LC transmissive elements. This architecture is highly compatible with existing LC fabrication processes and mitigates the risk of LC leakage. Experimental results demonstrate that a 42 × 42 element 1-D transmissive array based on the proposed unit cell achieves a wide-angle beam scanning capability of up to 70◦ from 23.6 to 24.9 GHz, exhibiting excellent beam reconfigurability. This study proposes a novel design paradigm for realizing low-cost, high-performance continuously tunable microwave transmissive metasurfaces, which hold broad applica- tion prospects in future communications, high-resolution imaging, and electronic countermeasures.