A miniaturized planar microstrip circularly polarized ultrawideband (UWB) antenna loaded by annular-ring slot is proposed and implemented in the paper. With the annular-ring slot loaded in the radiating patch of the antenna, the side of the radiating patch is connected by the asymmetric inverted L-shaped microstrip. At the same time, a quarter of a circle is cut off from the radiating patch. The above designed structure shows improvements on the operating frequency band and realization of the circular polarization radiation. A tapered microstrip is placed between the feed line and the radiating patch to achieve the slow-changing impedance transformation. The results of simulation and measurement demonstrate that the 3 dB axial ratio (AR) fractional bandwidth of the antenna structure achieves 21.25%. The peak gain within the 3 dB axial ratio bandwidth fluctuates between 3.74 and 4.59 dBi. The antenna shows good impedance matching in the ultrawideband range. With the compact structure of the UWB antenna, it has potential application in various wireless communication devices.

中文翻译：

---

环形环槽加载平面微带超宽带圆极化天线的设计

本文提出并实现了一种环形环缝加载的小型平面微带圆极化超宽带（UWB）天线。在天线的辐射贴片中装入环形圈槽的情况下，辐射贴片的侧面通过不对称的倒L形连接。形的微带。同时，从散热片上切下四分之一圆。以上设计的结构示出了对工作频带的改进以及圆偏振辐射的实现。锥形微带线放置在馈线和辐射贴片之间，以实现缓慢变化的阻抗变换。仿真和测量结果表明，天线结构的3 dB轴向比率（AR）分数带宽达到21.25％。3 dB轴向比率带宽内的峰值增益在3.74至4.59 dBi之间波动。该天线在超宽带范围内显示出良好的阻抗匹配。由于UWB天线的紧凑结构，它在各种无线通信设备中都有潜在的应用。