用于超高频射频识别的小型宽带高定向天线

基于Moxon天线具有高前后比和小型化的优点,并结合蝶形偶极子天线宽带的工作特性,设计了一款用于超高频(ultra-high frequency, UHF)射频识别(radio frequency identification, RFID)手持读写器的小型宽带高定向平面印刷天线。该天线采用Moxon和蝶形偶极子复合结构,利用平行双线馈电,引入微带渐变巴伦实现馈电平衡。最终天线尺寸为0.34λ₀×0.22λ₀(λ₀为中心频率工作波长),相比微带准八木天线实现了小型化。实测结果表明:在865~1 054 MHz频率范围内,天线的|S₁₁|＜-10 dB,增益均在3.5 dB以上,相对工作带宽达到20%;并且在UHF开放频段902~928 MHz频率范围内,天线的驻波比(voltage standing wave ratio, VSWR)小于1.4,前后比大于15 dB,增益高于5 dB。

Small broadband high directional antenna for UHF RFID

Based on the advantages of high front-to-back ratio and miniaturization of Moxon antenna, and combined with the broadband characteristics of bowtie dipole antenna, a compact broadband high directional planar printed antenna for ultra-high frequency (UHF) radio frequency identification (RFID) handheld reader is designed. The antenna adopts the composite structure of Moxon and bowtie dipole, uses the double-sided parallel-strip line feed, and introduces the microstrip tapered balun to achieve the feed balance. The ultimate antenna size is 0.34λ₀×0.22λ₀ (λ₀ is the wavelength of the central frequency), making it smaller than the microstrip quasi-yagi antenna. The measured results show that the reflection coefficient of the antenna in the 865~1 054 MHz frequency band is less than -10 dB, the gain is more than 3.5 dB, and the relative operating bandwidth reaches 20%. In addition, in the UHF unlicensed band of 902~928 MHz, the voltage standing wave ratio (VSWR) of the antenna is less than 1.4, the front-to-back ratio is greater than 15 dB, and the gain is higher than 5 dB.