ABSTRACT We report a broadband ultra-high frequency (UHF) radio frequency identification (RFID) tag antenna of compact size mounted on a metallic object in a near field communication (NFC) RFID system. One half of the square radiation patch has a semi-annular strip feedline embedded inside a semicircle-shaped slot to improve the antenna bandwidth and gain, and the other half of the radiation patch has an L-shaped slot and a shorting pin to increase the circular polarization (CP) bandwidth and reduce the antenna size. The resonant input impedance of the tag antenna can be tuned easily by varying the length of the semi-annular feedline, and the gap between the feedline and the etched semicircular slot. The proposed tag antenna has a wide measured impedance bandwidth (−10-dB |Γ|) covering the whole operating frequency range of 181 MHz (from 790 to 971 MHz) for a UHF RFID system. The measured 3-dB axis ratio (AR) bandwidth is 43 MHz (from 895 to 938 MHz), which is much larger than those of the CP tag antennas reported in the literature for metallic objects. Further experiment has shown that the proposed tag antenna can provide a stable reading range when mounted on metal plates of various sizes.

中文翻译：

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用于金属安装的紧凑型宽带圆极化 UHF RFID 标签天线

摘要 我们报告了一种安装在近场通信 (NFC) RFID 系统中的金属物体上的紧凑尺寸的宽带超高频 (UHF) 射频识别 (RFID) 标签天线。方形辐射贴片的一半在半圆形槽内嵌入半环形带状馈线，以提高天线带宽和增益，另一半辐射贴片有L形槽和短路销，以增加天线的带宽和增益。圆极化 (CP) 带宽并减小天线尺寸。标签天线的谐振输入阻抗可以通过改变半环形馈线的长度以及馈线与蚀刻半圆形槽之间的间隙来轻松调整。所提出的标签天线具有很宽的测量阻抗带宽 (-10-dB |Γ|)，覆盖了 UHF RFID 系统 181 MHz（从 790 到 971 MHz）的整个工作频率范围。测得的 3-dB 轴比 (AR) 带宽为 43 MHz（从 895 到 938 MHz），远大于文献中报道的金属物体 CP 标签天线的带宽。进一步的实验表明，当安装在各种尺寸的金属板上时，所提出的标签天线可以提供稳定的读取范围。