A frequency-reconfigurable ultra-wideband 1-bit phase-shifting metasurface

In this paper, a design method is presented for frequency-phase composite reconfigurable metasurfaces. <i>N</i> PIN diodes are introduced into the metasurface unit. The on-off states of these PIN diodes regulate the resonance characteristics of the unit, constructing 2<sup><i>N</i></sup> switchable reflection phase states. After optimizing structural parameters, these reflection phase curves show that there is a 180° phase difference between different frequency bands. By regulating frequency and phase regulation, the operational bandwidth of reconfigurable phase-shifting metasurface is effectively expanded. Based on this method, an ultra-wideband 1-bit phase-shifting metasurface unit is designed. Its 1-bit phase regulation band covers 5.4–13.0 GHz, with a relative bandwidth of 82.6%. Lumped capacitors are adopted and their positions are optimized to precisely adjust current distribution, enabling low-loss performance of the unit. The unit with a thickness of only 0.09 <i>λ</i> features low profile, low cost, and low loss. A 16×16 unit array is further constructed. Through coding regulation, the metasurface can generate scattering-controllable beams and orbital angular momentum vortex waves. Experimental results show that the metasurface can achieve a radar cross section reduction of over 10 dB in the ultra-wideband range, demonstrating dynamic beam steering capability and high-efficiency low-scattering performance. This design offers new insights into applying reconfigurable metasurfaces to broadband communication, radar stealth, and intelligent electromagnetic environment regulation.