NFC天线设计

摘要

NFC，即近距离无线通信，是工作在13.56MHz，用于近距离（小于10厘米）安全通信的无线通信技术。NFC天线作为手机支付系统的一个不可缺少的重要部分，已经伴随着手机支付功能的发展而日益受到非常广泛的研究和应用，国内外早已经开始专门研究用于手机支付功能的NFC天线，并提出了多种天线模型。

本文是基于天线基本理论以及天线仿真软件HFSS进行了大量的实验仿真，主要是研究NFC天线的设计方法及其小型化技术。本文共设计了三款天线，分别是双面矩形天线、双面螺旋天线、单面圆角矩形天线，同时仿真出天线的电感随天线各个参数的变化关系，主要是天线绕线数、绕线宽度及间隔与天线等效电感之间的变化关系，讨论并分析各个参数的变化趋势，总结规律，结合实际的需求，得到一款理论上性能最好的天线，并使用网络分析仪中进行了电感测试，测试结果与理论结果较一致。

本文还通过串并联电容和电阻的方式，对着三款天线分别进行了阻抗匹配，使得在13.56MHz处回波损耗达到最小，并且都达到了很好的匹配效果。本文的研究为各种不同尺寸、不同形状的小型天线设计奠定了理论基础，具有实际意义。

关键字：NFC 线圈天线输入阻抗回波损耗阻抗匹配

Abstract

NFC, namely close wireless communication, is working in 13.56MHz.It was used to close (within 10 cm) security communication as a kind of wireless communication technology. In mobile payment system, with the development of function mobile payment by extensive research and application, NFC antenna plays an indispensable part, specially for the mobile payment, the NFC antenna has the function of antenna model proposed at home and abroad.

In the master antenna theory basis and antenna simulation software HFSS conditions, this thesis did a large number of experimental simulation, mainly is the study of the NFC antenna design method and its miniaturization. The thesis designs three antennas, respectively is two-sided rectangular antenna, double-sided helical round antenna, single rounded rectangle antenna. At the same time, the inductance of the antenna simulation with the change of the various parameters antenna relations, mainly is the antenna coiling number, coiling width and with the antenna interval equivalent inductance of the relationship between changes, then discusses and analyzes the change trend of various parameters and make a conclusion. Combined with the actual demand, we get a theory of the best performance antenna. Finally, we use the network analyzer in inductance test, the results and the theoretical results are consistent.

This thesis also through the parallel capacitor and resistor way, to the three paragraphs antenna, the impedance matching is made in 13.56MHz place return loss minimum, and reached the very good matching effect. This thesis studies for many different sizes, different shapes of small antenna design and provides the theoretical basis and with the practical significance.

Keywords：NFC, Coil antenna, Input impedance, Return loss, Impedance matching

目录

摘要.................................................................................................................................................. I Abstract......................................................................................................................................... II 目录............................................................................................................................................... I II 第1章绪论 (1)

1.1 课题背景 (1)

1.2 国内外NFC技术的使用现状 (1)

1.3 仿真工具HFSS介绍 (3)

1.4 本文的研究内容 (4)

第2章NFC的工作原理 (5)

2.1 引言 (5)

2.2 天线的基本参数 (5)

2.3 NFC的工作原理 (8)

2.3.1 简介 (8)

2.3.2 通信模式 (9)

2.4 线圈天线 (11)

2.4.1 磁场分析 (11)

2.4.2 激励加载 (12)

2.5 电感耦合原理 (12)

2.6 天线电感的计算 (14)

2.7 小结 (15)

第3章双面矩形天线的设计 (17)

3.1 前言 (17)

3.1.1 天线尺寸的选择 (17)

3.1.2 天线电感值的大小 (17)

3.1.3 天线变量的选择 (17)

3.2 天线模型及参数 (18)

3.2.1 建模 (18)

3.2.2 天线模型 (19)

3.3 天线的电感随参数的变化分析 (19)