Optically transparent flexible tag antennas are highly desired for some applications, where unobtrusiveness and capability of mounting on curved surfaces are required. On the other hand, circular polarization minimizes signal degradation due to polarization mismatch between the reader and tag antennas, thus ensuring good communication quality and accuracy. In this letter, we present an optically transparent and flexible radio frequency identification passive tag antenna operating in the ultrahigh frequency band and exhibits circular polarization. It is thin, lightweight, and completely encapsulated inside transparent polymer, which protects it against dust, water, heat, and mechanical stress. The tag antenna is made by utilizing highly flexible and transparent conductive-mesh-polymer composite through a simple and low-cost manufacturing process. The antenna design is based on a planar square ring. It achieves a measured maximum read range of about 8.3 m and approximately 47 MHz (885–932 MHz) 3 dB axial-ratio bandwidth (ARBW).

中文翻译：

---

用于 UHF RFID 标签的光学透明柔性坚固圆极化天线

一些应用非常需要光学透明的柔性标签天线，在这些应用中需要不显眼和安装在曲面上的能力。另一方面，圆极化最大限度地减少了由于阅读器和标签天线之间的极化不匹配而导致的信号衰减，从而确保了良好的通信质量和准确性。在这封信中，我们展示了一种光学透明且灵活的射频识别无源标签天线，该天线在超高频段工作并呈现圆极化。它很薄、很轻，并且完全封装在透明聚合物中，可以保护它免受灰尘、水、热和机械应力的影响。标签天线采用高度灵活且透明的导电网状聚合物复合材料，通过简单且低成本的制造工艺制成。天线设计基于平面方环。它实现了约 8.3 m 的测量最大读取范围和约 47 MHz (885–932 MHz) 3 dB 轴向比带宽 (ARBW)。