In this article, a balanced low-profile, unidirectional circularly polarized (CP) stacked loop antenna with wide beamwidth is proposed. The antenna is composed of a pair of stacked nonuniform loops with different radii. The larger loop serves as a principal radiator, and the smaller one acts as an auxiliary one. The feed structure consists of a pair of dipole launchers with vertical transmission line. A bonded coaxial cable is used to simultaneously excite the loops at the center. As experimentally validated, the predicted results are in good agreement with the measured results. Compared to its unbalanced counterparts, the proposed antenna can exhibit impedance bandwidth of 40% (20 log |S₁₁| < −10 dB), 3-dB axial ratio (AR) bandwidth of 4%, front-to-back ratio (FBR) up to 18.5 dB and beamwidths in E-plane and H-plane of 118°/90° with low profile of 0.09-wavelength.

中文翻译：

---

平衡低剖面宽波束圆极化堆叠环形天线

在本文中，提出了一种具有宽波束宽度的平衡低剖面、单向圆极化 (CP) 堆叠环形天线。天线由一对不同半径的堆叠非均匀环路组成。较大的回路用作主要散热器，而较小的回路用作辅助散热器。馈电结构由一对带有垂直传输线的偶极子发射器组成。使用粘合同轴电缆同时激励中心的环路。经实验验证，预测结果与实测结果吻合良好。与其不平衡对应物相比，所提出的天线可以表现出 40% (20 log |S ₁₁| < -10 dB)，3-dB 轴比 (AR) 带宽为 4%，前后比 (FBR) 高达 18.5 dB，E 平面和 H 平面中的波束宽度为 118°/90°，低0.09 波长的轮廓。