Ultra-Wideband Frequency Beam-Steering Transparent Metasurface Enabled by Fine Metal Line

Abstract

Optically transparent and ultra-wideband metasurfaces are key enablers for future wireless–optical systems, offering electromagnetic functionality without compromising visible-light transmission. In this work, a flexible and transparent beam-steering metasurface is demonstrated, based on a three-layer fine metal line (FML) network patterned on PET substrates with an interleaved air gap. The metasurface enables linear polarization rotation and broadband phase compensation while achieving high optical transparency (∼70%) and mechanical flexibility. The transmitarray is optimized to steer beams over a broad frequency range from 13 to 32 GHz through passive frequency-dependent phase dispersion. Simulations and measurements confirm consistent beam deflection from 26° to 9°, with a peak gain of 26.03 dBi and stable aperture efficiency above 40%. Conformal simulations demonstrate that beam-steering performance is maintained under bending angles up to 20°, with no degradation in optical or electromagnetic functionality. Combining with ultra-wideband operation, transparency, conformability, and scalable fabrication, the proposed metasurface presents a promising solution for next-generation transparent antennas, radomes, and smart wireless–photonic platforms.