A Polarization-Controlled Beam Scanning Metalens with 3D Meta-Atoms in Frequency–Phase Decoupled Resonant Cavity Units

Size-variable units are commonly employed in metalens design for gradient phase modulation. However, geometric variations inherently couple the phase and resonant frequency responses, causing amplitude degradation across the operational bandwidth. This paper proposes a polarization-controlled beam scanning metalens utilizing resonant cavity units comprising novel 3D meta-atoms to achieve frequency–phase decoupling. The decoupling mechanism leverages opposite phase trends between resonator dimensions: increasing the resonator’s length reduces the resonant frequency and induces phase delay, whereas increasing the resonator’s height decreases the resonant frequency yet introduces phase advancement. By synergistically designing these two dimensions, stable transmission amplitude is maintained throughout the operating band, thus enabling high-Q resonators to serve as effective phase-shifting elements. To validate this concept, two metalenses employing localized phase gradients and geometric phase compensation are synthesized and integrated, achieving polarization-controlled and continuous wide-angle beam scanning (± 60°) at the Ku-band. The proposed metalens accomplishes continuous beam scanning with minimal gain roll-off and high gain, demonstrating significant potential for vehicular communication, maritime surveillance, and various mobile platform applications.