可用于金属表面上的平面型RFID标签天线设计

摘 要

无线射频识别技术(Radio Frequency Identification RFID)是从二十世纪九十年代兴起的一项利用射频信号进行非接触式双向通信，自动识别目标对象并获取相关信息数据的无线通信技术。它利用射频信号的空间耦合(交变磁场或电磁场)实现无接触信息传递并通过所传递的信息达到识别对象的目的．

一些研究已经提出了一种用于金属物体表面的平面倒F形状的贴片天线，实验证明这种天线在高传导性的材料上运作良好。当然，作为天线实体的一部分，大面积的地平面已经被包含在天线当中了。然而，这种结构的天线也存在一些缺点，如，由于需要许多放空引脚和大块的地平面，它的制造成本高、加工工艺高、制造困难。

本文中描述了一种简单的低成本的平面贴片天线，它通过结合两种旋向不同的偶极子天线结构减小了金属物体对天线的影响。在这种设计中，这两种不同结构天线的电抗在高传导性材料表面沿相反的方向变化，从而使得在金属表面也会有很稳定的性能。

关键词：RFID；贴片天线 ；金属表面；寄生电容 ；阻抗匹配

ABSTRACT

Radio Frequency Identification (RFID) is one of Automatic Identification technologies springing up in 1990s，which is used with the coupling of radio magnetic filed to realize wireless communication and identify the items．

Some studies have proposed tag antennas using a planar inverted-F structure for metallic objects. These antennas operate well on high-conductivity materials, since they already include large-area ground planes as part of the antenna body. These structures, however, have certain shortcomings, such as high cost and difficulty of fabrication, because they require shorting pins and a large ground plane.

In this Letter, we propose a simple low-cost planar tag antenna that reduces the influence of a metallic object by incorporating two different antenna structures; wherein the reactance of the two structures changes in opposite directions in the presence of high-conductivity surface materials. In affect, the antenna works well on high-conductivity surface materials.

Key words：RFID; tag antenna; metallic surface; parasitic capacitance; impedance match

目 录

第一章 绪 论 ..............................................................................................................1

1.1 RFID研究背景 ......................................................................................... 1

1.1.1 RFID技术发展历史 ....................................................................... 2 1.1.2 RFID应用领域 ............................................................................... 2 1.1.3 RFID技术的优势 ........................................................................... 4 1.2 RFID系统组成及工作原理 ..................................................................... 5

1.2.1 UHF以及微波频段阅读器工作原理 ............................................ 7 1.2.2 UHF以及微波频段应答器（电子标签）工作原理 .................... 8

第二章 天线介绍 ..........................................................................................................9

2.1 天线基本概念 ........................................................................................... 9 2.2 远区场分析 ............................................................................................. 12

第三章 HFSS（High Frequency Structure Simulator）简介 ...............................14

3.1 HFSS功能概述 ....................................................................................... 14 3.2 HFSS仿真原理 ....................................................................................... 15 3.3 HFSS天线仿真设计流程 ....................................................................... 17

第四章 可用于金属表面的平面型RFID标签天线设计 ........................................19

4.1 一种新颖的标签天线 ............................................................................. 19 4.2 仿真设计 ................................................................................................. 21

4.2.1 画出天线结构 ............................................................................... 21 4.2.2 定义端口和添加空气盒子 ........................................................... 25 4.2.3 定义求解参数与参数扫描 ........................................................... 27 4.2.4 定义远场球面 ............................................................................... 28 4.3 仿真结果与分析 ..................................................................................... 29

4.3.1 S参数分析..................................................................................... 29 4.3.2 观察天线阻抗 ............................................................................... 31 4.3.3 表面电流分布： ........................................................................... 33 4.3.4 天线辐射方向图： ....................................................................... 35

4.3.5 仿真小结 ....................................................................................... 37

结 论 ..........................................................................................................................38 参考文献 ......................................................................................................................39 附 录 ....................................................................................... 错误！未定义书签。 谢 辞 ......................................................................................................................41