To address the challenges of low efficiency and insufficient polarization control in generating cylindrical vector beams (CVBs) using single-layer metasurfaces, this study proposes an efficient CVB generation scheme based on a double-layer metallic metasurface. At 0.1 THz, the structure achieves high co-polarized transmission coefficients ( \(T_{xx}\) = 0.782, \(T_{yy}\) = 0.863) and a near- \(\pi\) phase delay (188.156°), successfully constructing a half-wave-plate functional unit. Full-wave simulations demonstrate that the structure maintains stable polarization conversion characteristics across the 0.08–0.12 THz band. Based on the Pancharatnam–Berry (PB) phase principle, a 31 × 31 metasurface array converts X- and Y-polarized incident plane waves into radially and azimuthally polarized CVBs, respectively, with clearly observed near-field polarization singularities. A comparative study under plane-wave and spherical-wave illumination reveals consistent polarization distribution at the center, while edge regions exhibit polarization scrambling due to wavefront curvature, nonuniform phase modulation, and limitations of the horn antenna model. Furthermore, leveraging the polarization-sensitive properties of the unit cell, vortex beams with topological charges \(l = \pm 1\) are generated under circularly polarized incidence. The metasurface was fabricated using standard printed circuit board (PCB) technology and validated via a terahertz imaging system. The measured field intensity distributions agree well with theoretical simulations, confirming the efficient generation and control of CVBs.
