We propose and analyze a circularly polarized slot antenna built on a ferrite substrate which is saturated normal to its plane and metalized on both sides. The antenna is built by etching a circular slot in the top metal layer. The antenna operates in the frequency range where the effective permeability of ferrite is negative. An accurate analytical model is derived for the antenna by solving the integral equation for the electric field on the circular slot. The results obtained are in good agreement with numerical simulations. Using the analytical results, a practical antenna is designed that uses a microstrip feed line. For an antenna with inner and outer radii of 4.9 and 5.9 mm, the results show a 3 dB axial ratio (AR) beam width of 200⁰ which is highly desirable in mobile or fixed satellite communication systems such as GPS. Furthermore, the operating frequency can be tuned in the 3.78–3.98 GHz range by changing the magnetic bias field from 15 to 30 kA/m. Compared to other CP antennas, our proposed antenna is compact, has at least twice 3-dB AR beamwidth (200⁰), and is tunable.

我们提出并分析了一种圆极化缝隙天线，该天线建立在铁氧体基板上，该基板垂直于其平面饱和并在两侧金属化。天线是通过在顶部金属层上蚀刻一个圆形槽来构建的。天线工作在铁氧体有效磁导率为负的频率范围内。通过求解圆形槽上电场的积分方程，推导出天线的精确解析模型。所得结果与数值模拟吻合良好。利用分析结果，设计了一种使用微带馈线的实用天线。对于内半径和外半径分别为 4.9 和 5.9 mm 的天线，结果显示 3 dB 轴比 (AR) 波束宽度为 200 ⁰这在移动或固定卫星通信系统（如 GPS）中是非常理想的。此外，通过将偏磁场从 15 更改为 30 kA/m，可以在 3.78-3.98 GHz 范围内调整工作频率。与其他 CP 天线相比，我们提出的天线结构紧凑，具有至少两倍的 3-dB AR 波束宽度（200 ⁰），并且是可调谐的。