Dual-band Dipole Antenna for ISO 18-6/ISO 18-4 Passive RFID Tag Applications Seunggil Jeon (1), Yeonsik Yu (1), Sungtek Kahng (2), Juderk Park (3), NaeSoo Kim (3), Jaehoon Choi (1) * (1)Department of Electrical and Computer Engineenng, Hanyang University 17 Haengdang-Dong, Seongdong-Gu, Seoul, 133-791, Korea Tel: +82-2-222-376, Fax: +82-2-2293-377 (2)Department of IT Communication Engineering, University of Incheon 177 Dohwa-Dong, Nam-Gu, Incheon, 42-749, Korea (3)RFID/USN Research Group, Telematics & USN Research Division, ETRI 161 Gajeong-dong, Yusong-gu, Daejeon, 35-7, Korea Email: jsg@ihanyang.ac.kr, choijh@hanyang.ac.kr* (corresponding author) Abstract In this paper, a slot coupled dipole antenna was presented for dual band passive RFID tag applications. Structures using a slot coupled feed and a resonator are explored to achievable dual band operation. It shows good impedance and radiation characteristics from 86 MHz to 96 MHz (ISO 18-6) and from 2.4 GHz to 2.5 GHz (ISO 18-4). The return loss is verified by comparing the calculations and measurements, which show good agreement. Radiation patterns are omni-directional for operation frequencies. Numerical results are calculated using Ansoft HFSS (High Frequency Structure Simulator). Introduction Radio Frequency Identification (RFID) of objects or people has become very popular in many services in the industry, distribution logistics, manufacturing companies and goods flow systems [1]. Several frequency bands have been assigned to the RFID applications, such as 125 khz, 13.56, 91 MHz and 2.45 GHz. At present, most of RFID systems operate in UHF range (typically at 91 MHz) and higher frequencies that utilize free microwave ISM band such as 2.45 GHz are under active development. In this paper, a novel design of a dual band dipole antenna is presented. It consists of a dipole antenna and a slot coupled structure. By properly selecting a coupled slot on a dipole antenna which covers the band of ISO 18-6 RFID tag applications, dual band and tunable impedance bandwidth characteristics for ISO 18-4 RFID tag applications could be achieved. Details of the antenna design and both theoretical and experimental results are presented and discussed. Antenna Configuration The configuration of the proposed antenna design is shown in Fig. 1. The antenna 1-4244-123-2/6/$2. 26 IEEE 4285
is symmetrical and its basis is a dipole structure with feed terminals. A coupled slot with lengths of L 2, S 2 and S 3 was placed inside of dipole antenna with length L 1. A numerical simulation [2] shows that the phase difference between the current at the end of dipole antenna (L 1 ) and that of coupled slot section (L 2 ) is about 18. It shows each section (L 1, L 2 ) is operated as the approximated halfwave dipole antenna with center feeding [3]. To determine the detailed design parameters for the given structure, the tag antenna was optimized to work at the frequency bands of ISO 18-4 and ISO 18-6. The three design goals considered were a suitable impedance bandwidth, omni-directional radiation pattern and simple structure. Optimized design parameters were found with the following dimensions: W=15 mm, L 1 =151 mm, L 2 =31 mm, W 1 =5.5 mm, W 2 =5 mm, S a =S b =1 mm, S feed =2 mm, S 1 =1 mm, S 2 =21 mm, S 3 =22.5 mm. Antenna parameters used in this paper are S a (width of coupled slot) and S 2 (length of coupled slot). Based on those parameters the antenna characteristics are calculated and shown in the next section. Experimental results Fig. 2 shows calculated and measured return loss characteristics for the fabricated antenna. The measured return loss bandwidth less than -1dB for ISO 18-6 application is from 84 MHz to 96 MHz and the bandwidth (return loss < - 1dB) for ISO 18-4 application is from 2.33 GHz to 2.51 GHz. The proposed design has sufficient bandwidth to cover the requirement of RFID system in the ISO 18-6 and ISO 18-4 standards. Agreement between the experiment and simulation is generally good. Fig. 3 shows return loss characteristics when lengths L 2 and S a are varied. There are two resonant frequencies, 91 MHz and 2.45 GHz where the return losses are less than about -2 db. When the lengths of S 2 =2 mm and S a =1 mm, the return loss and band width characteristic are suitable for the applications. Fig. 4 shows radiation pattern at 91 MHz and 2.45 GHz for proposed antenna. Almost the omni-directional patterns in the H-plane are observed. Conclusion The analysis and design of a slot coupled dipole antenna with dualband performance has been proposed and implemented. With the insert of a coupled slot to the dipole antenna operating at 91 MHz, the proposed antenna can operate at 2.45 GHz. The antenna is simple and symmetrical and has good impedance bandwidth and radiation pattern. This design is not only suitable for use in ISO 18-6 (91 MHz) but is also applicable to ISO 18-4 (2.45 GHz) RFID systems. References [1] K. Finkenzeller, RFID Handbook, Wiley, England, 1999 4286
[2] Ansoft High Frequency Structure Simulator (HFSS), Ver. 1., Ansoft Corporation [3] W. L. Stutzman, Antenna Theory and Design, Wiley, America, 1998 (a) overall view (b) dimension Figure 1. Structure of the proposed passive RFID tag antenna Return Loss (db) -1-2 Simulation Measure -4.5 1. 1.5 2. 2.5 3. Frequency (GHz) Figure 2. Calculated and measured return loss of the proposed antenna 4287
Return Loss (db) -1-2 S 2 = 2mm S 2 = 22mm S 2 = 24mm S 2 = 26mm -4.5 1. 1.5 2. 2.5 3. 3.5 Frequency (GHz) (a) Return Loss (db) -1-2 S a = 1mm S a = 2mm S a = 3mm S a = 4mm -4.5 1. 1.5 2. 2.5 3. 3.5 Frequency (GHz) (b) Figure 3. Calculated return loss with varied parameters: (a) S 2 and (b) Sa -9-9 -6-12 -6-12 -1-1 -2-15 -2-15 -1-2 -4-4 -2-1 -18-1 -2-4 -4-2 -1-18 3-2 15 3-2 15-1 -1 6 12 9 (a) ISO 18-6 (91 MHz) E H E 6 12 H 9 (b) ISO-18-4 (2.45 GHz) Figure 4. Measured far-field radiation pattern 4288
易迪拓培训 专注于微波 射频 天线设计人才的培养网址 :http://www.edatop.com 射频和天线设计培训课程推荐 易迪拓培训 (www.edatop.com) 由数名来自于研发第一线的资深工程师发起成立, 致力并专注于微波 射频 天线设计研发人才的培养 ; 我们于 26 年整合合并微波 EDA 网 (www.mweda.com), 现已发展成为国内最大的微波射频和天线设计人才培养基地, 成功推出多套微波射频以及天线设计经典培训课程和 ADS HFSS 等专业软件使用培训课程, 广受客户好评 ; 并先后与人民邮电出版社 电子工业出版社合作出版了多本专业图书, 帮助数万名工程师提升了专业技术能力 客户遍布中兴通讯 研通高频 埃威航电 国人通信等多家国内知名公司, 以及台湾工业技术研究院 永业科技 全一电子等多家台湾地区企业 易迪拓培训课程列表 :http://www.edatop.com/peixun/rfe/129.html 射频工程师养成培训课程套装该套装精选了射频专业基础培训课程 射频仿真设计培训课程和射频电路测量培训课程三个类别共 3 门视频培训课程和 3 本图书教材 ; 旨在引领学员全面学习一个射频工程师需要熟悉 理解和掌握的专业知识和研发设计能力 通过套装的学习, 能够让学员完全达到和胜任一个合格的射频工程师的要求 课程网址 :http://www.edatop.com/peixun/rfe/11.html ADS 学习培训课程套装该套装是迄今国内最全面 最权威的 ADS 培训教程, 共包含 1 门 ADS 学习培训课程 课程是由具有多年 ADS 使用经验的微波射频与通信系统设计领域资深专家讲解, 并多结合设计实例, 由浅入深 详细而又全面地讲解了 ADS 在微波射频电路设计 通信系统设计和电磁仿真设计方面的内容 能让您在最短的时间内学会使用 ADS, 迅速提升个人技术能力, 把 ADS 真正应用到实际研发工作中去, 成为 ADS 设计专家... 课程网址 : http://www.edatop.com/peixun/ads/13.html HFSS 学习培训课程套装该套课程套装包含了本站全部 HFSS 培训课程, 是迄今国内最全面 最专业的 HFSS 培训教程套装, 可以帮助您从零开始, 全面深入学习 HFSS 的各项功能和在多个方面的工程应用 购买套装, 更可超值赠送 3 个月免费学习答疑, 随时解答您学习过程中遇到的棘手问题, 让您的 HFSS 学习更加轻松顺畅 课程网址 :http://www.edatop.com/peixun/hfss/11.html `
易迪拓培训 专注于微波 射频 天线设计人才的培养网址 :http://www.edatop.com CST 学习培训课程套装该培训套装由易迪拓培训联合微波 EDA 网共同推出, 是最全面 系统 专业的 CST 微波工作室培训课程套装, 所有课程都由经验丰富的专家授课, 视频教学, 可以帮助您从零开始, 全面系统地学习 CST 微波工作的各项功能及其在微波射频 天线设计等领域的设计应用 且购买该套装, 还可超值赠送 3 个月免费学习答疑 课程网址 :http://www.edatop.com/peixun/cst/24.html HFSS 天线设计培训课程套装套装包含 6 门视频课程和 1 本图书, 课程从基础讲起, 内容由浅入深, 理论介绍和实际操作讲解相结合, 全面系统的讲解了 HFSS 天线设计的全过程 是国内最全面 最专业的 HFSS 天线设计课程, 可以帮助您快速学习掌握如何使用 HFSS 设计天线, 让天线设计不再难 课程网址 :http://www.edatop.com/peixun/hfss/122.html 13.56MHz NFC/RFID 线圈天线设计培训课程套装套装包含 4 门视频培训课程, 培训将 13.56MHz 线圈天线设计原理和仿真设计实践相结合, 全面系统地讲解了 13.56MHz 线圈天线的工作原理 设计方法 设计考量以及使用 HFSS 和 CST 仿真分析线圈天线的具体操作, 同时还介绍了 13.56MHz 线圈天线匹配电路的设计和调试 通过该套课程的学习, 可以帮助您快速学习掌握 13.56MHz 线圈天线及其匹配电路的原理 设计和调试 详情浏览 :http://www.edatop.com/peixun/antenna/116.html 我们的课程优势 : 成立于 24 年,1 多年丰富的行业经验, 一直致力并专注于微波射频和天线设计工程师的培养, 更了解该行业对人才的要求 经验丰富的一线资深工程师讲授, 结合实际工程案例, 直观 实用 易学 联系我们 : 易迪拓培训官网 :http://www.edatop.com 微波 EDA 网 :http://www.mweda.com 官方淘宝店 :http://shop369289.taobao.com 专注于微波 射频 天线设计人才的培养易迪拓培训官方网址 :http://www.edatop.com 淘宝网店 :http://shop369289.taobao.com