折射率渐变透镜的数值设计

传统折射率渐变透镜的设计要求初级馈源天线具有稳定的相位中心，这就限制了透镜的应用范围。为拓宽透镜的应用范围，提出了一种折射率渐变透镜的数值设计方法，通过对馈源天线的极化电场离散采样获得相位信息，并据此设计透镜，随后用金属短线结构的新型人工电磁材料来实现这种透镜。这种设计方法简单灵活，对馈源天线没有限制。以经典矩形贴片天线为例，比较了贴片天线和透镜天线的回波损耗和远场方向图，结果表明运用这种方法设计的透镜使贴片天线的增益提高了2 dB，口径效率从62%提高到了99%。

Numerical method for designing gradient refractive index lens

The orthodox method for designing gradient refractive index lens requires that the feeding antenna possesses a steady phase center, which restricts the application of this lens. To break through the restriction, the paper presents a numerical method. By sampling the polarized electric field of the feeding antenna, phases of the electric field are got. Then they are used to design the gradient refractive index lens, which is fabricated from metamaterials with cut-wires structure. The design method is straightforward and flexible, with no restriction on the feeding antenna. Taking patch antenna as demonstration, the return losses and radiation patterns of the patch antenna and the lens antenna are compared. The data show that the lens obviously improves the gain and efficiency of the patch antenna. The gain is improved by 2 dB and the efficiency is increased from 62% to 99%.