中文摘要：

轮胎嵌入式超高频无源RFID系统在轮胎生命周期管理和安全监控中将发挥十分重要的作用。为此,该文研究了轮胎嵌入式超高频无源RFID系统功率传递特性。轮胎嵌入式超高频无源RFID系统中,读写器和电子标签间的无线链路需要穿过空气和轮胎,路径损耗主要包括空气-轮胎界面间的反射损耗和轮胎中的衰减。基于轮胎介电常数和空气-轮胎界面的边界条件,研究轮胎嵌入式超高频无源RFID系统功率传递特性,提出了一种基于终端开路同轴探针的轮胎介电常数的比对测量方法,建立了轮胎嵌入式超高频无源RFID系统功率传递模型。数值分析表明,提出的基于端开路同轴探针的轮胎介电常数的比对测量方法误差小,测量、仿真的反射系数差的绝对值小于0.04,而为了提高轮胎嵌入式超高频无源RFID系统读取距离和可靠性,读写器天线应采用水平极化方式,并且尽可能直视电子标签;应合理设计电子标签嵌入轮胎的深度,避免功率传递函数处于波谷位置。该研究可为轮胎嵌入式超高频无源RFID电子标签与胎压监测系统的设计提供参考。

英文摘要：

Acting as sensors, passive radio frequency identification devices（RFID） tags can avoid sensor nodes bulky and realize battery-powered. So, ultra high frequency（UHF） passive RFID tags embedded in tires have a deep impact on tire life cycle management and tire monitoring,and have been used widely in the USA and the European Union. However, the transmission range is one of the hardest challenges in UHF passive RFID embedded in tires, because the rubber makes it harder to read the tag. The main difference between the common RFID and RFID embedded in tires is the communication medium, which attenuates RF power from the reader in RFID embedded in tires. To improve the transmission range and reliability of RFID embedded in tires, it is of great concern to study power transmission of wave propagation for UHF passive embedded RFID in tires, because the tags do not contain any battery and rely on the electromagnetic field for both power and communication. In this work, we studied the power transmissions for UHF passive embedded RFID in tires. In UHF passive embedded RFID systems in tires, the bidirectional radio link between reader and tags goes through air and tires.The total path loss is caused by several factors： reflection loss due to reflected power at tire-air boundaries,attenuation loss in the tires, and spreading loss which is simply due to the radiation properties of antenna. Each of these factors can be analyzed using the permittivity of tires and tire-air boundary conditions. So, the power transmissions are based on the permittivity of tires and tire-air boundary conditions. We use the OCP（open-ended coaxial probe） method to measure the permittivity of tires. By analyzing the radio link for UHF passive RFID, we establish a model of power transmissions of UHF embedded RFID in tires and make numerical analyses.Numerical analyses show that the error of the OCP methods for measuring the permittivity of tires is small, and the absolute error between the measured reflection coefficients and the simulated