This study investigates a low-profile circularly polarized (CP) antenna using coplanar waveguide feeding. Rectangular-shaped slots and an inverted L-shaped slit are entrenched into the ground plane to enhance the impedance bandwidth of the antenna. Furthermore, the antenna is implemented with six elliptical electromagnetic band gap structures on its substrate to enhance the −10 dB return loss bandwidth and also to generate CP waves. The experimental and theoretical results closely match each other and indicate that a simple and compact design antenna with dimensions of 0.317λ0 × 0.317λ0 × 0.023λ0(λ0 is the operating wavelength at 4.74 GHz in free space) achieves 36.9% (3.91–5.68 GHz) of the −10 dB return loss bandwidth and 9.98% (4.09–4.52 GHz) of the 3-dB axial ratio bandwidth, thus making it a favorable entrant for radio altimeter and wireless avionics infra-communication systems.

本研究调查了使用共面波导馈电的低剖面圆极化 (CP) 天线。矩形槽和倒 L 形槽固定在接地平面中，以提高天线的阻抗带宽。此外，该天线在其基板上采用六个椭圆电磁带隙结构实现，以增强 -10 dB 回波损耗带宽并产生 CP 波。实验和理论结果紧密匹配，表明设计简单紧凑的天线尺寸为 0.317 λ 0 × 0.317 λ 0 × 0.023 λ 0 ( λ 0是自由空间中 4.74 GHz 的工作波长）实现了 -10 dB 回波损耗带宽的 36.9%（3.91-5.68 GHz）和 3-dB 轴比带宽的 9.98%（4.09-4.52 GHz），因此使其成为无线电高度计和无线航空电子基础设施通信系统的有利进入者。