Design of the reconfigurable Mmwave-metasurface based on liquid crystals

Abstract Dynamically tunable metasurface, a new generation of electromagnetic manipulation devices, has shown significant application potential in millimeter-wave communication, intelligent sensing, phased array antennas, and other related domains. Nonetheless, the majority of current dynamically tunable metasurface continue to face significant hurdles regarding compactness, tuning speed, and extensive angular operational range. Here, we propose a deep-subwavelength (≈ λ/11) metasurface modulator employing a 30 μm-thick liquid crystal (LC) layer to improve the tuning speed, while providing capabilities of amplitude/phase modulation. The underdamped condition with maximum 2π phase shift is investigated by the coupled mode theory (CMT). Subsequently, as a proof of concept,the finite element method is employed to establish the metasurface with specific pattern parameters to verify the establishment of the overdamping state. The simulations results indicate that the modulator's capacity for amplitude and phase modification can be achieved by the tunable dielectric constant of liquid crystal. The amplitude modulation |r|2 range is 0.126 to 0.938, while the phase modulation Δφ of 277° is attained at 28.58 GHz. Furthermore, the modualtion capacity of the amplitude and phase can be maintained under a broad angular range of 70°. This work establishes physics-based design guidelines for the design and downsizing of millimeter wavefront manipulation devices.