A high-resolution near-field focusing metasurface lens (MSL) was proposed to meet the high-resolution and miniaturization requirements of focusing devices in the Ka-band passive millimeter wave (PMMW) imaging system. Based on coaxial ring structure with polarization insensitivity, the design of a single refraction surface phase gradient MSL capable of focusing on plane waves is completed. Furthermore, the near-field focusing is realized by the method of phase superposition. The overall size of the lens s is 80 × 80 mm², composed of 25 × 25 unit with the thickness of only 0.24λ. The feed source used a tapered slot antenna based on substrate integrated waveguide. The simulation results indicate a good spatial resolution of the presented lens, which can focus the electromagnetic wave radiated from the feed antenna at 70 mm with the focal spot size of 9 mm. The lens can effectively reduce the system volume and achieve high resolution imaging when utilized in PMMW imaging system.

为了满足Ka波段无源毫米波（PMMW）成像系统中聚焦器件的高分辨率和小型化要求，提出了一种高分辨率近场聚焦超表面透镜（MSL）。基于偏振不敏感的同轴环结构，完成了能够聚焦平面波的单折射面相位梯度MSL的设计。此外，近场聚焦是通过相位叠加的方法实现的。透镜整体尺寸为 80 × 80 mm ²，由厚度仅为 0.24 λ的 25 × 25 单元组成. 馈源采用基于基片集成波导的锥形缝隙天线。仿真结果表明，该透镜具有良好的空间分辨率，可以将从馈电天线辐射的电磁波聚焦在 70 mm 处，焦斑尺寸为 9 mm。该镜头用于PMMW成像系统，可有效减小系统体积，实现高分辨率成像。