Rapid Prototyping RFID Antennas Using Direct-Write

Optimization of radio-frequency identification (RFID) tags often requires several iterations of antenna design/fabrication/testing to meet cost and performance targets. The use of a rapid prototyping approach for antenna development would allow the designer an inexpensive and fast route to the refinement process. In this study, the performance of a commercial-off-the-shelf ultrahigh frequency (UHF) etched copper antenna was compared to printed silver antennas prepared by the following three direct-write techniques: maskless mesoscale materials deposition; matrix-assisted pulsed laser evaporation direct-write; and, collimated aerosol beam direct-write. The morphologies of the antennas were analyzed using contact and optical profilers with sheet resistance also being measured. Operational characteristics were determined by mounting silicon integrated circuits (IC) to the four different types of antennas. The performance of tags that utilized direct-write silver antennas was comparable to the copper-based commercial tag. To our knowledge, this is the first demonstration where some of the direct-write rapid prototyping attributes (e.g., slight overspray, overlap of written lines, overall thickness less than 500 nm) are shown to not seriously impede RFID tag performance. These results demonstrate the utility of direct-write for rapid prototyping studies for UHF RFID antennas.      

Geometric and Compaction Dependence of Printed Polymer-Based RFID Tag Antenna Performance

Radio frequency identification (RFID) tags with printed antennas are lower in cost but have lower performance than those with metal antennas. Printed antennas can replace metal ones if the performance is increased without raising cost. The performance of printed antennas can be increased if the series resistance in the antennas is lowered. The resistance is dependent on the line thickness and the resistivity of the conductive ink. Printed antennas with different line thicknesses were fabricated to investigate the effect of compaction and thickness on the resistance. The resistance of the printed antenna coils decreased by more than 40% after compaction, while the inductance and the parasitic capacitance were unchanged. RFIDs with compacted printed antennas were found to have significantly increased read range. RFIDs with thick printed antennas were fabricated and tested. These RFIDs were shown to have read ranges comparable to the RFIDs with copper wire antennas. Moreover, a geometry-independent plateau for the read range was found. The presence of a plateau is valuable for thick-line printed antenna since the plateau will enable the usage of low precision printing techniques to lower tag fabrication cost.     

模切法RFID天线制造技术

现有被动式RFID标签天线制造技术存在着不足：主流的蚀刻法工艺繁琐,产出速度慢,对环境有污染;印刷法使用的导电银油墨的成本居高不下,而且天线可靠性也存在问题;电镀法在大批量生产时才有成本优势。为此,提出了一种基于模切技术的天线制造方法：针对一款图案精细的超高频RFID天线,用两次模切排废的方法,得到了天线图形。天线与R...     

一种新颖的基于公司徽标的RFID UHF天线

提出了一种基于公司徽标设计RFID UHF标签天线图案的方法,详细介绍了其原理、设计过程及其天线特点。并给出了两个基于"华中科大"和"无锡邦普"字符的RFID UHF天线实例,并且制作了实物并测试,测试结果表明两者最大读距都在8 m以上。相比较于市面上的偶极子天线,这类天线具有增益高、阻抗匹配容易和工作频带宽等特点,更重要的是它可以指导人们开发基于自己公司徽标的天线。     

Reliability of washable wearable screen printed UHF RFID tags

Wearable antennas have an enormous potential in future welfare, healthcare, and childcare applications. These applications require the antenna to be an integral and unnoticeable part of clothing and to be able to endure different environmental conditions and repeated washing. We manufactured UHF RFID tags by screen printing polymer thick film ink antennas on two different fabric substrates and tested the effects of different types of washing cycles on two key properties of wearable passive UHF RFID tags: threshold power and theoretical read range. Despite the detrimental impact of the washing cycles and detergents, the RFID tags remained wirelessly readable at the distances of beyond 1.3 m, which is satisfactory for many field applications.     

Performance of Printed Polymer-Based RFID Antenna on Curvilinear Surface

The performance of flexible printed RFID tags affixed onto cylindrical containers is dependent on the inductive behavior of the bent antenna on the tag. Conductive polymeric coil antennas were screen printed onto flexible substrates, and the coil resistances, the inductances, and the S-parameters of the antenna coils were measured and analyzed. The RFID dies were mounted onto the antenna coils and the read ranges were characterized as a function of curvature. The results show that the coil inductance decreased slowly with increasing curvature, and the maximum read range of the tags was markedly reduced with the curvature. The decrease in the coil inductance and the maximum read range were hypothesized to vary with the projected bent coil area instead of the geometric coil area. Experimental results confirmed that the maximum read range of an RFID tag affixed on a curvilinear surface can be predicted by the classical inductive coupling model with the bent projected coil area. On the basis of the experimental and analytical results, a reading reliability factor of two is proposed as a design parameter for flexible RFID tags.     

Chipless RFID tags fabricated by fully printing of metallic inks

This paper reviews recent advances in fully printed chipless radio frequency identification (RFID) technology with special concern on the discussion of coding theories, ID generating circuits, and tag antennas. Two types of chipless tags, one based on time-domain reflections and the other based on frequency domain signatures, are introduced. To enable a fully printed encoding circuit, linearly tapering technique is adopted in the first type of tags to cope with parasitic resistances of printed conductors. Both simulation and measurement efforts are made to verify the feasibility of the eight-bit fully printed paper-based tag. In the second type of tags, a group of LC tanks are exploited for encoding data in frequency domain with their resonances. The field measurements of the proof-of-concept of the tag produced by toner-transferring process and flexible printed circuit boards are provided to validate the practicability of the reconfigurable ten-bit chipless RFID tag. Furthermore, a novel RFID tag antenna design adopting linearly tapering technique is introduced. It shows 40 % save of conductive ink materials while keeping the same performance for conventional half-wave dipole antennas and meander line antennas. Finally, the paper discusses the future trends of chipless RFID tags in terms of fabrication cost, coding capacity, size, and reconfigurability. We see that, coupled with revolutionary design of low-cost tag antennas, fabrication/reconfiguration by printing techniques, moving to higher frequencies to shrink tag sizes and reduce manufacturing cost, as well as innovation in ID generating circuits to increase coding capacities, will be important research topics towards item-level tracking applications of chipless RFID tags.     

Segmented loop antenna for UHF near-field RFID applications

A segmented loop antenna is presented for ultra-high frequency (UHF) near-field radio frequency identification (RFID) applications. The proposed segmented configuration makes the current along the loop remain in-phase even though the perimeter of the loop is comparable to the operating wavelength, so that a strong and uniform magnetic field is generated in the region surrounding the antenna. The antenna printed on a FR4 printed circuit board (PCB) with an overall size of 160 x 180 x 0.5 mm achieves good impedance matching and uniform magnetic field distribution over an operating bandwidth of 800?1040 MHz, which is desirable for UHF near-field RFID reader applications.     

Virtual Private Networks [Guest Editorial]

Handheld radio frequency identification reader units become increasingly important with the adoption of passive ultra-high frequency RFID systems in supply chain, warehouse, and retail store management. Important requirements for the handheld reader unit are ergonomic size and weight, sufficient battery life, and suitable read range for the desired applications. In addition, usability of the reader unit in terms of reading directions and orientations of tags has to be taken into account. This article presents a performance comparison of compact reader antennas for a handheld UHF RFID reader unit. The reader antennas presented in this study are designed to be affixed either inside the casing of the reader unit or into an external reader antenna module. The presented antenna designs have been optimized with finite element method modeling. The resonance frequency and bandwidth characteristics are analyzed using modeled and measured results. Read range measurement results with the antenna designs affixed to the handheld reader are presented and analyzed to verify the practical performance. All the antenna designs presented in this article are applicable to a handheld RFID reader unit     

一种面向卷烟包装新型超高频rfid标签天线设计

本文设计了一种新型的抗金属无源UHF射频识别(RFID)印刷标签天线.该天线可以应用在卷烟包装上,仿真和实测数据证明,在915MHz处天线的阻抗为(20+j149)Ω,能和Alien Higgs -2芯片很好的实现共轭匹配.该标签天线的工作带宽为31MHz,通过RFID阅读器实测表明,所设计的标签天线读取距离可达到0.8m.     

手持式超高频RFID读写器天线设计技术综述

天线作为手持式超高频射频识别技术(Radio frequency identification technology,RFID)读写器中的关键部件,其性能直接影响到RFID系统的读写距离和读写器体积大小.论文分析研究各种手持式超高频RFID读写器天线的设计技术,重点介绍应用最广的微带天线设计方法、技巧及发展趋势.     

Broadband RFID tag antenna with quasi-isotropic radiation pattern

A passive RFID tag antenna in the UHF band using two bent dipoles and a modified double T-matching network is proposed. The antenna was fabricated with a thin copper layer printed on a 50 /spl mu/m-thick PET substrate for low-cost production. The proposed antenna provided a quasi-isotropic radiation pattern and a fairly broad bandwidth S/sub 11/<-10 dB, 8.5%) for conjugate-matching with a commercial tag chip. The efficiency of the antenna was about 90% in the operating frequency band. The measured readable range was between 170 -240 cm for an arbitrary rotation angle of the tag.     

A Novel Graphene Conductive Ink Based Circular Patch Antenna for 2.4 GHz Application

Graphene conductive ink based microstrip line fed circular patch is presented in this paper. The main objective of this work is to replace copper with graphene which is an emerging promising material, in the field of patch antennas with conventional rigid substrates using a simple printing technique and to measure its performance. The prototyped screen printed graphene antenna is perfectly radiating and the return loss, VSWR and gain of the graphene antenna is found to be better than conventional copper antenna. Also, the bandwidth of the graphene antenna is 1.6 times greater than that of the conventional copper antenna on rigid substrate.

     

适用于IT设备资产管理的RFID标签天线设计

针对用于IT设备资产管理的RFID系统存在读取率低、读取范围小、易受干扰的问题,设计了一种具有抗金属、抗移动通信终端干扰、高增益的双频微带天线。HFSS仿真结果显示,标签天线在CDMA800和GSM的UHF频段 S11值大于-10 dB,天线最大增益为7.28 dBi,标签最大读取距离理论估值为17.66 m。设计的RFID标签天线适应IT设备资产管理环境特殊要求。     

UHF reader loop antenna for near-field RFID applications

A novel reader loop-type antenna for ultra-high-frequency (UHF) near-field radio frequency identification (RFID) applications is presented. This antenna, printed on a 0.8 mm-thick FR4 substrate with a diameter of 16 cm, is composed of four curved strips and four pairs of coupled stubs, and achieves a wide impedance bandwidth from 840 to 1300 MHz. The proposed structure can make large currents along the loop so that a strong and uniform magnetic field distribution is excited in the region around the antenna. Measurements show that the antenna operating with a commercial reader demonstrates good performance of tag identification with inductive coupling for near-field RFID applications.     

纳米导电油墨及其在印刷天线中的应用

文章以印刷RFID天线作为印刷电子技术的应用实例,介绍了利用纳米导电油墨印刷RFID天线的优势、进展与发展展望。     

A Dual-Band Circularly Polarized Hexagonal Ring Antenna for Handheld RFID Readers

In this paper, a compact, lightweight, low-profile dual-band circularly polarized antenna is presented for handheld radio frequency identification (RFID) readers. The proposed antenna consists of two concentric hexagonal rings and a feed network printed on different layers of the dielectric substrate. The antenna configuration exploits a stacked-coupled technique for gain enhancement and single-port feeding for easy manufacturing. The center frequencies of the two resonating bands are 0.92 GHz (UHF) and 2.45 GHz (ISM). The antenna exhibits circular polarization characteristics in both the resonating bands, therefore encountering the losses due to polarization mismatch and increasing the tag detection reliability. A prototype of the proposed RFID antenna is simulated and fabricated, and experimental results are in close agreement. The peak antenna gain is 3.3 dB and 5 dB in the UHF and ISM bands, respectively. The overall size of the RFID antenna is 80 mm?×?80 mm?×?7.76 mm.

     

Design of the compact UHF RFID meander-line antenna loaded with CPW elements

In this paper, Coplanar Waveguide (CPW) elements are used to load UHF RFID meander-line antennas. Although, the insertion of these elements allow to design small antennas their gain decrease depending on the CPW structures are connected. In this sense, a new location to print CPW elements in the meander-line antenna is proposed aiming not to deteriorate the gain. A multi-objective optimization algorithm is applied in the meander-line antennas loaded with CPW elements in different positions and a comparison between their performances is done. To validate the computational model of the proposed antenna its input impedance is measured.     

一种新型RFID宽带标签天线的分析与设计

由于各个国家分配给UHF频段RFID系统的频率不同,以及全球跨国供应链中物品跟踪管理的发展要求,宽带RFID标签天线已然成为各国学者研究的一个热点。文中采用在辐射贴片上开槽来拓展带宽的方法,设计了一款双T型槽宽带标签天线。所设计的天线为无通孔与短路结构的简单天线,尺寸仅为33mm×25mm×1.6mm,工作带宽覆盖了各个国家分配给UHF频段的频率范围,最大理论读取距离可达7.58m。通过改变槽的尺寸可以方便地调节天线与标签芯片之间的匹配。与其他宽带标签天线相比,该天线在小型化、读取距离方面具有明显优势。由于测试条件有限,天线输入阻抗实测曲线走势与仿真曲线基本一致,但实测曲线向低频偏移了200MHz左右,实测值与仿真值相比有一定程度的衰减。     

UHF RFID tag antenna with broadband characteristic

A novel UHF RFID tag antenna with broadband characteristic is presented. The structures of T-matching network and double symmetrical radiating patches shorted to the ground plane are employed. The measured half-power bandwidth of the proposed antenna is 12.9% and it covers two major frequency bands. The maximum readable distance of the tag achieved 6.5 m in the RFID bands for North America and Europe. All the results show that the proposed antenna can work not only in air but also on metallic objects in the North America and Europe UHF RFID band.