A high-gain bow-tie antenna with double-layer phase-gradient metasurface (PGMS) lens is proposed. A modified bow-tie antenna is designed as a feed, which has end-fire characteristics. The proposed PGMS can transform quasi-spherical electromagnetic wave to plane wave within the frequency band from 1.7 to 2.1 GHz, thereby the proposed lens antenna has a good beam focusing effect. The measured gain is from 9.5 to 12.8 dBi and a −3 dB gain bandwidth of around 20% is achieved. At the same time, the gain increases 6.5 dB on average in the whole working frequency band. Simulated and measured results show that the designed modified bow-tie antenna with PGMS lens has high gain and high directivity, which can well meet the requirement of microwave imaging system.

中文翻译：

---

具有相位梯度超表面透镜的高增益蝴蝶结天线

提出了一种具有双层相位梯度超表面（PGMS）透镜的高增益蝴蝶结天线。改进的领结天线设计为馈源，具有端射特性。所提出的PGMS可以将1.7至2.1 GHz频段内的准球形电磁波转换为平面波，因此所提出的透镜天线具有良好的波束聚焦效果。测得的增益为 9.5 至 12.8 dBi，实现了约 20% 的 -3 dB 增益带宽。同时，增益在整个工作频段平均增加6.5dB。仿真和实测结果表明，所设计的改进型带PGMS透镜的蝴蝶结天线具有高增益和高方向性，可以很好地满足微波成像系统的要求。