This article presents a compact slot array antenna combined with quad-polarization for mm-wave applications. A novel modified short-circuit termination with inclined slot is proposed in this paper and a dual-layer structure has been adopted to achieve miniaturization and also to design a circular polarization feeding network. Two linear polarization feeding networks are designed independently so that four polarization states can be realized. Four polarization states, namely vertical linear polarization, horizontal linear polarization, left hand circular polarization (LHCP), and right hand circular polarization (RHCP) can be switched by feeding corresponding ports. Judging from impedance matching and axial ratio (AR), the antenna exhibits wide bandwidth. The −10 dB impedance bandwidth and 3 dB AR bandwidth are better than 14.2% (26-30 GHz) with gain about 5-8 dBic for both LHCP and RHCP. The linear polarization states have |S₁₁| < −10 dB and a gain of 5-7 dBi over 26.5-29.5 GHz (10.7%). The size of the slot array antenna is 65 × 65 × 1.156 mm and measured results are consistent with simulations.

中文翻译：

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28GHz双层基片集成波导缝隙阵列天线结合四极化

本文介绍了一种紧凑型缝隙阵列天线，结合了适用于毫米波应用的四极化。本文提出了一种新型的带有斜槽的改进短路终端，采用双层结构实现小型化并设计圆极化馈电网络。两个线性极化馈电网络独立设计，可实现四种极化状态。通过馈入相应的端口，可以切换垂直线偏振、水平线偏振、左旋圆偏振（LHCP）和右旋圆偏振（RHCP）四种偏振状态。从阻抗匹配和轴比（AR）来看，该天线具有较宽的带宽。−10 dB 阻抗带宽和 3 dB AR 带宽优于 14。2% (26-30 GHz)，LHCP 和 RHCP 的增益约为 5-8 dBic。线偏振态有 |S₁₁ | < −10 dB，在 26.5-29.5 GHz (10.7%) 范围内增益为 5-7 dBi。缝隙阵列天线尺寸为 65 × 65 × 1.156 mm，实测结果与仿真一致。