A Wideband Millimeter-Wave Circularly Polarized Metasurface Antenna Array Loaded With Dual-Layer LC Decoupling Resonators

This letter presents a wideband, high-gain, and low-profile dual-layer metasurface (MTS) circularly polarized (CP) antenna array for millimeter-wave (MMW) applications. A modal-split synergistic frequency tuning (MSFT) strategy guided by characteristic mode analysis (CMA) is proposed: by achieving controlled separation of orthogonal modes via H-shaped slots and utilizing the dual-layer MTS structure for synergistic tuning to broaden the modal bandwidth, this strategy fundamentally realizes the synchronized expansion of impedance and axial ratio (AR) bandwidths. Additionally, a novel dual-layer LC decoupling resonator (LCDR) network is introduced to efficiently suppress array mutual coupling by generating anti-phase compensating magnetic fields. Measured results of a 4 × 4 array prototype indicate that, with an ultra-low profile of only 0.13$\lambda _{0}$, it achieves an impedance bandwidth of 39.20%, an AR bandwidth of 38.75%, and a peak gain of 20.45 dBic.