This paper presents the design and validation of a slot-patch-hybrid circularly polarized antenna array for 28 GHz millimeter (mm) wave (mm-wave) applications. The proposed design has a simple geometry that facilitates the fabrication process, which is otherwise a challenging task due to the sub-mm dimensions of the circuit in the mm-wave band. In the proposed structure, aperture-coupled series slot-fed array is utilized to excite the 45° inclined pair of patches. The feeding array aperture is designed by printing a straight microstrip feed line with a matching stub at the open end. Further, a coupling slot is etched underneath the feed line in the conventional horizontal position, and two vertical slots are merged toward each end of the slot. For realization of the series phased array of (1 × (4 × 2)) elements, the slots are placed half guided wavelength away extending the array network along the feed line. A pair of the radiating patches are loaded on the top of the vertical slots. To ensure excitation of the 90° phase-shifted orthogonal field components of equal magnitude, the loaded patches are rotated by 45° in the azimuth plane. The produced circularly polarized (CP) fields are further refined by an additional diagonal radiating slot etched in the middle of the pair of radiating patches parallel to the non-radiating edges. With the combination of radiating patches and the slots, a wide axial ratio bandwidth of 27.5–28.5 GHz, broad impedance bandwidth, a highly directional beam, and a peak realized CP gain of 15.15 dBic is achieved. For realizing omnidirectional radiation pattern necessary for the base station applications, 3-dimentional hexagonal/octagonal topology is utilized in six- and eight-antenna configurations. A detailed theoretical and numerical analysis and the corresponding results shows that the adjacent beams could be merged together constructively to form omnidirectional radiation patterns. The advantage of the proposed technique is the ease of implementation without affecting the major performance figures.

本文介绍了用于 28 GHz 毫米波 (mm-wave) 应用的缝隙贴片混合圆极化天线阵列的设计和验证。所提出的设计具有简单的几何形状，便于制造过程，否则由于电路在毫米波段中的亚毫米尺寸，这是一项具有挑战性的任务。在所提出的结构中，孔径耦合的串联槽馈电阵列用于激发 45° 倾斜的贴片对。馈电阵列孔径是通过在开口端打印带有匹配短截线的直微带馈线来设计的。此外，在常规水平位置的馈线下方蚀刻了耦合槽，并且两个垂直槽朝向槽的每一端合并。为了实现 (1 × (4 × 2)) 元素的串联相控阵，槽被放置在半导波长之外，沿馈线延伸阵列网络。一对辐射贴片装载在垂直槽的顶部。为确保激发 90° 相移正交场分量等幅值，加载的贴片在方位平面旋转 45°。产生的圆偏振 (CP) 场通过在平行于非辐射边缘的一对辐射贴片中间蚀刻的附加对角辐射槽进一步细化。通过辐射贴片和槽的组合，实现了 27.5-28.5 GHz 的宽轴比带宽、宽阻抗带宽、高度定向的波束和 15.15 dBic 的峰值实现 CP 增益。为了实现基站应用所需的全向辐射图，3 维六边形/八边形拓扑用于六天线和八天线配置。详细的理论和数值分析以及相应的结果表明，相邻的波束可以建设性地合并在一起以形成全向辐射方向图。所提出的技术的优点是易于实施而不影响主要性能数据。