We propose a method to design compact circularly polarized (CP) antenna using a novel sunshine-shaped slotted radiating patch, which exhibits slow wave and other interesting properties. The structured radiating patch introduces adjustable coupling between a pair of orthogonal modes (TM₁₀ mode and TM₀₁ mode) to facilitate good axial ratio (AR) and reflection parameters of the antenna simultaneously in the radiating frequency band. A $\pi $ /2 balun is employed to excite the TM₁₀ and TM₀₁ modes by using back feeding structure. Based on the proposed method, a compact left-hand CP antenna is designed, fabricated, and measured to verify the feasibility of the design method. The whole antenna is $0.17\lambda _{0}\times 0.17\lambda _{0}$ in dimension ( $\lambda _{0}$ is the wavelength in free space) and the measured maximum gain is 5 dBic in the working band, and 3 dB AR bandwidth is 0.4% for left-hand CP.

中文翻译：

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使用阳光形开槽贴片的紧凑型圆极化天线设计

我们提出了一种使用新型阳光形开槽辐射贴片设计紧凑型圆极化 (CP) 天线的方法，该贴片具有慢波和其他有趣的特性。结构化辐射贴片在一对正交模式（TM ₁₀模式和TM ₀₁模式）之间引入了可调耦合，以促进天线在辐射频带内同时获得良好的轴比（AR）和反射参数。一种 $\pi $ /2 balun 用于激励TM ₁₀和TM ₀₁模式，采用后馈结构。基于所提出的方法，设计、制造和测量了一个紧凑的左手CP天线，以验证该设计方法的可行性。整个天线是 $0.17\lambda _{0}\times 0.17\lambda _{0}$ 在维度 ( $\lambda _{0}$ 是自由空间中的波长），测得的最大增益在工作频段为 5 dBic，左手边 CP 的 3 dB AR 带宽为 0.4%。