A wideband circularly polarized (CP) waveguide array antenna is proposed in this article. The proposed array antenna consists of four antipodally ridged elements and a compact feeding network with two orthogonal septa inserted to a stepped cavity. Both the components are wideband and they can work independently or together. The proposed topology gives a good solution to feed a $2 \times 2$ waveguide subarray which is the basis of large-scale arrays. It exhibits a larger working bandwidth than the array antennas fed by high-order mode cavities. A prototype is fabricated using 3-D printing and milling technologies. Measured results demonstrate a bandwidth of 40.3% from 9.9 to 14.9 GHz, in terms of the reflection coefficients less than −15 dB and the axial ratios smaller than 3 dB. An expanded $8 \times 8$ CP array antenna is explored based on the proposed $2 \times 2$ subarray to show the potentials of our design, and a total efficiency over 78% within a bandwidth of 38.7% is obtained by simulation.

中文翻译：

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一种紧凑高效馈电网络的宽带圆极化阵列天线

本文提出了一种宽带圆极化（CP）波导阵列天线。所提出的阵列天线由四个对映脊元件和一个紧凑的馈电网络组成，其中两个正交隔板插入到阶梯腔中。这两个组件都是宽带的，它们可以独立工作或一起工作。所提出的拓扑提供了一个很好的解决方案来馈送 $2 \times 2$ 波导子阵列是大规模阵列的基础。与由高阶模腔馈电的阵列天线相比，它具有更大的工作带宽。原型是使用 3D 打印和铣削技术制造的。测量结果表明，从 9.9 到 14.9 GHz 的带宽为 40.3%，反射系数小于 -15 dB，轴比小于 3 dB。一个扩展 $8 \times 8$ CP 阵列天线的探索基于所提出的 $2 \times 2$ 子阵列来展示我们设计的潜力，通过仿真获得了在 38.7% 的带宽内总效率超过 78%。