超高频RFID近场系统的研究设计

发布时间：2018-05-16 16:02

本文选题：无线射频识别技术 + 超高频近场系统　；参考：《杭州电子科技大学》2015年硕士论文

【摘要】：随着互联网和通信技术的日益成熟，物联网（IoT）这个新兴概念越来越多的被人所提及，而作为物联网核心技术的无线射频识别技术（RFID）也被广泛的应用于物流、制造、公共安全等领域中。一直以来，RFID技术的应用方向分为超高频的托盘级识别和高频/低频的物品级识别，在同一频段同时实现托盘级识别和物品级识别一直备受关注，超高频近场系统被认为是解决这一难题的主要方案。天线是RFID系统中的一个重要组成部分，直接影响着整个系统的工作性能。本项目的近场系统工作在天线的感应场区，采用电感耦合的工作方式，以环天线理论和半波偶极子天线理论为基础，分别对近场系统的标签天线和读写器天线展开研究：（1）通过分析超高频近场标签天线电路模型，提出偶极子天线加载电小环天线的天线结构。但由于尺寸的限制，单个偶极子臂有效长度不足以达到谐振频率所对应的四分之一波长，故无法保证天线工作频率达到设计要求；而且近场标签要有较强的环境适应能力需要有块状结构形成大电容以增强储存能量的能力。因此，提出一种特殊结构电小环集成圆弧形偶极子臂的天线结构，并用HFSS进行建模仿真，优化设计后得到最优结构和尺寸，最终仿真结果显示天线中心频率为910MHz，与芯片阻抗匹配，，电压驻波比小于1.5。（2）以读写器天线近场区域能够产生均匀的电磁场分布为设计核心，提出反向电流对加载开口谐振环的天线结构：用偶极子臂构建反向电流对，用电小环天线构建开口谐振环，并用HFSS进行建模仿真，优化设计后得到最优结构和尺寸，仿真结果显示读写器近场区域内电磁场分布均匀，且具有较强的电场强度和磁场强度，天线中心频率为920MHz，与50欧姆实现阻抗匹配，电压驻波比小于1.5。最后，对该超高频RFID近场系统测试，测试结果显示该系统阅读性能良好，可达6.5cm；系统具有较强的环境适应性，贴附在各种材质上的阅读距离均可大5cm，但在金属环境中使用时需离开金属表面至少1cm。
[Abstract]:With the development of Internet of things and communication technology, the new concept of IoT has been more and more mentioned, and RFID, the core technology of Internet of things, has been widely used in logistics and manufacturing. In areas such as public safety The application of RFID technology has been divided into ultra-high frequency pallet level identification and high frequency / low frequency object level identification. UHF near-field system is considered to be the main solution to this problem. Antenna is an important part of RFID system, which directly affects the performance of the whole system. The near field system of this project works in the inductive field region of the antenna. Based on the theory of loop antenna and half wave dipole antenna, the label antenna and reader antenna of the near field system are studied by inductively coupled mode. 1) by analyzing the circuit model of UHF near-field tag antenna, the antenna structure of electric small loop antenna loaded with dipole antenna is proposed. However, due to the limitation of size, the effective length of a single dipole arm is not enough to reach the 1/4 wavelength corresponding to the resonant frequency, so it is impossible to guarantee the antenna working frequency to meet the design requirements. In addition, the near field tag needs to have a large capacitance to enhance the energy storage ability to have a large block structure to be able to adapt to the environment. Therefore, an antenna structure with a special structure, the electric small ring integrated circular arc dipole arm is proposed, and the optimal structure and size are obtained by HFSS modeling and simulation. The simulation results show that the center frequency of the antenna is 910MHz, which matches the chip impedance, and the VSWR is less than 1.5. Taking the near-field distribution of electromagnetic field in the near field of reader antenna as the design core, an antenna structure with reverse current pair loaded with open resonant ring is proposed: the reverse current pair is constructed by dipole arm, and the open resonant ring is constructed by electric small loop antenna. Using HFSS to model and simulate, the optimal structure and size are obtained after optimized design. The simulation results show that the electromagnetic field in the near field region of the reader is uniform, and has a strong electric and magnetic field intensity. The center frequency of the antenna is 920MHz, and the impedance is matched with 50 ohms. The VSWR is less than 1.5. Finally, the test results of the UHF RFID near-field system show that the reading performance of the system is good, which can reach 6.5 cm, and the system has strong environmental adaptability. The reading distance attached to various materials can be 5 cm, but when used in metal environment, it must be at least 1 cm off the metal surface.
【学位授予单位】：杭州电子科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TP391.44

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