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.     

Applicability of Metallic Nanoparticle Inks in RFID Applications

Radio frequency identification (RFID) antennas for HF and UHF frequencies are ink-jet printed using commercially available silver nanoparticle ink. Quality factors of 5.3 and 9.4 are obtained for coil antennas targeted for 13.56 MHz when the printing and sintering process is repeated two and three times, respectively. The measured maximum effective aperture of the printed UHF antenna is only some decibels lower than that of an equivalent etched copper antenna and the maximum reading distance with 0.5 W (ERP) transmitted power is 3 m for continuous reading. These results suggest that obtaining a low enough series resistance for printed coils is challenging while printed RFID antennas for UHF do not set as strict requirements on conductivity. With a perfectly optimized structure, a UHF tag antenna printed in just one layer of ink can be practically equal in performance with the traditional etched copper and aluminum tags.      

UHF频段无源RFID标签阅读距离影响因素分析

在物品识别领域,RFID技术应用的快速发展对RFID标签的读出距离不断提出新的要求.通过对增加UHF900 MHz频段无源电子标签阅读距离的主要方法的研究,着重从电子标签设计中的如下几个要素进行了探讨:天线及标签芯片阻抗匹配、天线及标签芯片的品质因数以及标签基底材料的选择.     

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.     

Design of a RFID System for Real-Time Tracking of Laboratory Animals

In this paper, a real-time RFID system capable of tracking laboratory animals is designed and implemented. Four passive RFID tags based on low frequency are designed and implemented. The tags can be read by any RFID reader that operates on the low frequency range 125–134 kHz. The tags are designed through the investigation of various antenna, encoding, modulation, and energy harvesting techniques. The tag receives the electromagnetic signal via the antenna, and converts it to a DC signal that the microcontroller can use to manipulate the electromagnetic signal with the data such that the reader can decode the unique tag identifier. RFID sensors are designed and implemented to collect data from various monitored areas of a semi natural environment. The data is sent to a central data coordinator for pre-processing and middleware for data error checking, display and storage. The RFID system can successfully detect and store movement data in real time. A read range of 14.5 cm is achieved.     

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.     

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.     

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。     

轮胎嵌入式小型化UHF RFID 电子标签弯折天线设计

为提高轮胎嵌入式UHF RFID 电子标签读取可靠性,需要解决一对矛盾,即一方面,为保证电子标签与轮胎有良好的粘合性和绑定性,要求标签天线尺寸足够小;另一方面,轮胎无线电环境差,轮胎材料对电磁波的固有介质损耗和干扰要求电子标签天线尺寸应足够大,以提高电磁辐射能力。针对以往设计方法复杂、不利于标签与轮胎绑定的问题,根据Bode-Fano 阻抗匹配的约束,利用弯折天线的周期性和紧凑性,提出了一种简单、具有良好阻抗特性和绑定特性的轮胎嵌入式小型化UHF RFID 弯折天线方法,设计了一种物理空间受限的轮胎嵌入式小型化UHF RFID 弯折天线。HFSS 仿真验证表明,设计的天线在833 ~971MHz 频带范围内回波损耗小于-10dB,覆盖了美国RFID 标准带宽902 ~928MHz,最大辐射增益为2. 4dBi。最后,通过设计的轮胎嵌入式RFID 电子标签测试,结果表明:当读取距离小于90cm 时,标签识别率大都大于80%;当读取距离小于50cm 时,标签识别率大于90%,标签与轮胎具有良好的绑定效果,满足设计要求。     

An RFID Tag Using a Planar Inverted‐F Antenna Capable of Being Stuck to Metallic Objects

This letter presents the design for a low‐profile planar inverted‐F antenna (PIFA) that can be stuck to metallic objects to create a passive radio frequency identification (RFID) tag in the UHF band. The designed PIFA, which uses a dielectric substrate for the antenna, consists of a U‐slot patch for size reduction, several shorting pins, and a coplanar waveguide feeding structure to easily integrate with an RFID chip. The impedance bandwidth and maximum gain of the tag antenna are about 0.3% at 914 MHz for a voltage standing wave ratio (VSWR) of less than 2 and 3.6 dBi, respectively. The maximum read range is about 4.5 m as long as the tag antenna is on a metallic object.     

小型化低剖面UHF RFID抗金属标签天线设计

针对超高频抗金属射频识别(RFID)标签的小型化和低剖面需求,提出了一种可用于金属表面的超高频RFID标签天线,其尺寸为50 mm×20 mm×0.9 mm。该设计采用CST MWS软件进行建模仿真,分析了嵌入式馈电结构尺寸变化和矩形开槽尺寸变化对标签天线输入阻抗的影响,并调整相应参数以达到标签天线输入阻抗与芯片阻抗的共轭匹配。实测结果表明,标签天线输入阻抗与芯片阻抗匹配良好,在910 MHz处有最大实测阅读距离为4.3 m,且具有小尺寸和低剖面,可应用于物流、医疗、零售等多种领域的金属场景。     

Testing the effects of temperature and humidity on printed passive UHF RFID tags on paper substrate

This article is an interesting substrate material for environmental-friendly printable electronics. In this study, screen-printed RFID tags on paper substrate are examined. Their reliability was tested with low temperature, high temperature, slow temperature cycling, high temperature and high humidity and water dipping test. Environmental stresses affect the tag antenna impedance, losses and radiation characteristics due to their impact on the ink film and paper substrate. Low temperature, temperature cycling and high humidity did not have a radical effect on the measured parameters: threshold power, backscattered signal power or read range of the tags. However, the frequency response and the losses of the tags were slightly affected. Exposure to high temperature was found to even improve the tag performance due to the positive effect of high temperature on the ink film. The combined high humidity and high temperature had the most severe effect on the tag performance. The threshold power increased, backscattered power decreased and the read range was shortened. On the whole, the results showed that field use of these tags in high, low and changing temperature conditions and high humidity conditions is possible. Use of these tags in combined high-humidity and high-temperature conditions should be carefully considered.     

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.     

A 2.45-GHz Near-Field RFID System With Passive On-Chip Antenna Tags

The design of a 2.45-GHz near-field RF identification (RFID) system with passive on-chip antenna (OCA) tags is very challenging as the efficiency of RF power conversion is very low. It poses multidisciplinary research challenges such as ultra-low-power circuits design, semiconductor process technology, and integrated antenna design. This paper describes the designs of such an RFID system, the reader, and OCAs, as well as the passive tag integrated circuits in detail. The passive tag chip with 128-bit nonvolatile memory has been realized using CMOS 0.13- technology. The OCA is fabricated on top of the chip using post-processing technology. The complete RFID tag with an integrated OCA is smaller than 0.5- with a thickness of 0.1 mm. With the reader generating an output power of 0.5 W, the RFID system is able to perform with RF read/write functions at a distance of .     

低成本射频识别标签模拟前端分析与设计

提出一种新的低成本射频识别标签模拟前端,同时兼容ISO 14443A和ISO 14443B协议.相比于传统模拟前端,本设计采用面积更小的单线圈天线代替传统大面积多圈天线,使得标签的封装成本大幅度降低.考虑到单线圈天线的性能降低,设计了一个新的具有高效率低启动电压的电荷泵整流电路.整体电路采用SMIC 0.18μm EEPROM工艺实现,测试结果显示电荷泵驱动120kΩ等效负载时,整流效率达到36%,输入交流幅度仅0.5V时,输出电压达到电路工作电压1V.标签的阅读距离可以达到22cm.     

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.      

Design of RFID tag antenna for metallic surfaces using lossy substrate

A novel low-cost antenna design suitable for radio frequency identification (RFID) tags mountable on metallic surfaces is presented. The antenna consists of two shorted patches printed on a lossy FR4 substrate and their radiating edges are facing each other. A tag chip feed is placed between two patches and a stacked shunt capacitor is formed to adjust the antenna impedance. The proposed design reduces the substrate loss and improves the radiation efficiency by more than double compared with a conventional planar inverted-F antenna, which is verified by simulation and measurement.     

Miniature and near-3D omnidirectional radiation pattern RFID tag antenna design

A planar and miniature (0.09lambda times 0.13lambda) radio frequency identification (RFID) tag antenna is described whose radiation pattern is near omni-directional in three dimensions, with less than 2.6 dB gain deviation in all directions. The antenna is comprised of an open-loop radiating element, which is excited by a small loop. The minimum and maximum read ranges of the implemented RFID tag are approximately 2.3 and 2.6 m, respectively. Comparison between the simulated and measured results for the radiation and read patterns are shown to be in good agreement.     

Design of planar RFID tag antenna for metallic objects

Proposed is a novel RFID tag antenna consisting of an inner spiral dipole, an outer bent dipole and a double T-matching network that is suitable for attaching to metallic objects. For low-cost fabrication, the antenna is printed on a single-layer substrate without a ground plane or shorting pins. The detailed design parameters of the antenna were optimised using the Pareto genetic algorithm so that the antenna would operate adequately both in fiee space and on metallic objects. The antenna was fabricated, based on the optimised design, and the performance in fiee space and on a metallic surface were measured. The half-power matching bandwidth (VSWR < 5.8) and the reading range of the antenna in fiee space were 7.6% and 2.8 m, while on a metallic surface the corresponding values were 0.8% and 1.8 m. For non-metallic surfaces (i.e. low dielectric targets, 2 < epsiv_r < 4), the antenna exhibited the reading range of 2-3 m.