This letter presents a novel wideband printed circuit board (PCB)-stacked Luneburg lens antenna with a flared open edge for multibeam scanning application at 5G millimeter-wave band. The lens consists of two groups of parallel PCBs. Each group includes 12 layers of low-cost FR4 PCB, which are fixed by metal screws. Inside the lens there is no dielectric, resulting in an air-filled structure. With drilling holes of different radius in each PCB layer (except the top and bottom layers), the air spacing between the two groups of PCBs varies discretely which approximates the graded refractive index. Eleven antipodal linearly tapered antennas are placed on the focuses of the lens as feed elements, permitting the beam to cover a wide angular range. To enhance the gain of the lens, the radiation aperture is flared, like an H-plane horn. Measurements of the lens antenna with a diameter of 130 mm show good agreement with the theoretical predictions. The measured impedance bandwidth covers 26–37 GHz with isolations better than 18.8 dB. The measured peak gain is around 15.4 dBi at 29 GHz. By switching the 11 feed elements, the overall 2-D beam scanning coverage is up to ±72°. The results indicate that the proposed Luneburg lens antenna demonstrates a good application potential for 5G millimeter wave wireless communication.

中文翻译：

---

适用于5G毫米波应用的宽带PCB堆叠式空气填充Luneburg透镜天线

这封信介绍了一种新颖的宽带印刷电路板（PCB）堆叠式Luneburg透镜天线，其天线具有张开的开口边缘，适用于5G毫米波波段的多光束扫描应用。镜头由两组平行的PCB组成。每组包括12层低成本FR4 PCB，这些层由金属螺钉固定。镜头内部没有电介质，从而形成了充满空气的结构。在每个PCB层（顶层和底层除外）中钻不同半径的孔时，两组PCB之间的气隙离散地变化，这近似于渐变的折射率。透镜的焦点上放置了11个对角线线性锥形天线，作为馈电元件，使波束能够覆盖较宽的角度范围。为了增强透镜的增益，辐射孔像H平面喇叭一样张开。直径为130 mm的透镜天线的测量结果与理论预测吻合良好。测得的阻抗带宽覆盖26-37 GHz，隔离度优于18.8 dB。在29 GHz处测得的峰值增益约为15.4 dBi。通过切换11个馈电元件，整个二维光束扫描范围可达±72°。结果表明，提出的Luneburg透镜天线具有5G毫米波无线通信的良好应用潜力。