为了提高太赫兹通信天线的增益和定向性, 提出了“井”字堆叠型透镜天线。该透镜天线工作在太赫兹第一大气传播窗口内, 由初级馈源天线和透镜两部分构成。设计了角锥喇叭天线作为透镜天线的初级馈源; 根据菲涅耳-基尔霍夫衍射理论和傍轴近似条件设计了“井”字堆叠型透镜用于聚焦太赫兹波, 并分析了透镜结构在平面波入射时的聚焦场分布。利用控制变量法分析了透镜天线的全波周期和焦径比等结构参数对其远场辐射性能的影响。对所设计的透镜天线进行了实物加工和测试。实验结果表明: “井”字堆叠型透镜天线的加工和组装工艺简便, 具有对称的辐射模式, 在320~380 GHz的工作频段内的增益高于26.4 dB, 3 dB主瓣宽度低于4.8°, 基本满足太赫兹通信系统对天线的高增益和强定向性等要求。

In order to improve the gain and directionality of terahertz communication antenna, a cross-like rings stacked lens antenna was proposed in terahertz atmospheric transmission I window. The lens antenna was consisted of a diagonal horn antenna and a multilayer stacked lens. The diagonal horn antenna was adopted as the primary feed and the multilayer comprised cross-like rings. Far field characteristics of the lens antenna was studied by using Fresnel-Kirchhoff diffraction theory and paraxial approximation. Furthermore, the effects of the full-wave period and the focus diameter ratio on radiation characteristics were analyzed by using variable-controlling approach. The proposed lens antenna was fabricated and experimentally tested. The results show that the proposed lens antenna has common processing methods and axisymmetric radiation patterns. The gain is over 26.4 dB and the 3 dB main lobe beamwidth is lower than 4.8° throughout the whole operation bandwidth from 320 to 380 GHz. The good focusing characteristics and great directionality indicate that the designed lens antenna is qualified for applications in THz wireless communication systems.