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.     

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.      

一种超高频射频识别读写器天线

本文提出了一种适用于我国UHF RFID读写器的宽带圆极化叠层微带天线,通过选用廉价FR4板、空气层介质和对角线切角的正方形贴片组成叠层结构,采用S型水平蜿蜒带条激励主辐射贴片的馈电方式,展宽了天线的阻抗带宽和轴比带宽.所提出的S型水平蜿蜒带条馈电技术,实现了对称的辐射方向性图.给出了天线设计思路,并利用电磁仿真软件分...     

Near-Field Loop Antenna for the UHF RFID Reader

A loop antenna for near field readers is proposed.Through periodic interdigital capacitors,the phase of the current on the loop is compensated and kept in phase.Hence,a loop with a perimeter of one wavelength at 900 MHz achieves a uniform near magnetic field distribution inside the loop.A novel method is proposed to evaluate the performance of the coplanar waveguide (CPW) to coplanar stripline (CPS) transition,which is used as a balun for the feeding network in this paper.This loop antenna has a 70 MHz operating bandwidth and 12 cm maximum reading range when the output power is 24 dBm,which is suitable for most near field radio frequency identification (RFID) applications.     

Design of an Ultra‐Compact UHF Passive RFID Tag Antenna for a Medical Sample Tube

In this letter, a small‐sized ultra‐high frequency (UHF) RFID tag antenna for a medical sample tube is proposed. The RFID tag antenna is designed and fabricated based on the circular loop antenna used in the UHF band (Korea standard, 917 MHz to 923.5 MHz). The tag antenna size is reduced using a circular meander stub. The antenna has a physical size of 8 mm, which is about λ/40 in electrical length. The proposed tag antenna is molded into a medical sample and multitag identification is performed.     

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.     

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.     

A broadband circularly polarized antenna of square-ring patch for UHF RFID reader applications

A circularly polarized, broad bandwidth, square-ring patch antenna for radio-frequency identification (RFID) is proposed. The antenna has a dimension of 100 × 100 × 22.9 mm³. By using a Wilkinson power divider and a patch-antenna structure, a measured 3-dB axial-ratio bandwidth of approximately 140 MHz (16.47%), an impedance bandwidth of 136 MHz (15.81%), and a measured peak gain of approximately 6.8 dBic are being achieved. The operating band of the proposed antenna is suitable for China (840–846 MHz), Europe (865–868 MHz) and the United States (902–928 MHz) ultra-high frequency (UHF) RFID applications.     

HF RFID Reader Antenna with Loop Switch for Avoiding Magnetic Coupling

This paper studies the magnetic coupling between two adjacent loop antennas that are parallel to each other in a plane and presents a new practical method to avoid the resulting magnetic coupling interference. The study focuses on the high frequency radio‐frequency identification (RFID) system for casino applications, where several loop antennas are closely built into a game table to monitor gaming chips. In this case, neighboring loop antennas may severely interfere with each other by magnetic coupling, which leads to the malfunction of the RFID system. In this paper, we present a practical loop antenna with a new loop switch circuit for avoiding magnetic coupling. The loop switch circuit is integrated with a matching circuit and automatically operated by using an interrogating signal from a reader. We verified the validity of the proposed design by showing that an RFID reader with the proposed antenna can exactly and separately read the gaming chips placed on the different betting zones of a game table.     

一种新型圆极化UHF通用型RFID读写器天线

面向超高频(UHF)通用型射频识别(RFID)读写器天线的应用需求,设计了一款完全覆盖全球UHF(840-960MHz)频段的RFID圆极化读写器天线。天线采用平面缝隙贴片结构,以共面波导(CPW)馈电方式实现宽频带圆极化特性。测试结果表明,天线的阻抗带宽为735-1014MHz(S11<-10dB),相对带宽31.9%,并且在840-960MHz频段内S11<-20dB,3dB轴比带宽为838-1134MHz,相对带宽30.0%,工作频带内有大于3.5dBi的平坦增益。仿真结果与测试结果基本吻合,天线结构精简,易于加工,满足全球UHF RFID读写器天线的应用需求。     

Characteristics of a Metal-Backed Loop Antenna and its Application to a High-Frequency RFID Smart Shelf

In this paper, a metal-backed loop antenna (MBLA) at high frequency (HF) is characterized and applied to a radio-frequency identification (RFID) smart-shelf system. The antenna is investigated in terms of impedance matching, resonant frequency, magnetic-field intensity/field distribution, quality factor, and detection range. The study shows that the magnetic-field distribution of the metal-backed loop antenna can be effectively controlled by changing the size as well as the separation of the backing metal plate. As a result, the detection range of an RFID system using such an antenna can be controlled. Such a feature offers great promise for the metal-backed loop antenna in applications for RFID smart-shelf systems. For such systems, controlling the coupling zone of the antennas is vital for constraining the interference between the antennas in adjacent tiers of the shelves, in order to achieve high system-detection accuracy. In addition, using a metal-backed loop antenna provides more flexibility for RFID smart-shelf-system design and implementation, so that the system is more cost effective.     

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.

     

Inductively coupled small self resonant coil (SSRC) reader antennas for HF RFID applications

A new model of inductively coupled high frequency radio frequency identification (HF RFID) reader antennas is presented in this paper based on the idea of using the self resonance frequency (SRF) of a small multi turn coil. The introduced multi turn small self resonant coil (MT SSRC) antenna is mathematically analyzed in terms of SRF, number of turns, dimensions and dielectric characteristics of the insulation, where present. Based on the analysis, a compact planar version of MT SSRC antennas having two turns, the two turn planar SSRC (TTP SSRC), is investigated and the dependency of the SRF to the antenna dimension is observed. A TTP SSRC antenna operating at 13.56 MHz is fabricated and is compared with an old model of HF RFID antennas; an optimized Q factor and a more uniform near field pattern is obtained for the new antenna. The benefits of the obtained optimized Q factor and uniform near pattern is explained for smart shelf application. Also, a number of TTP SSRC antennas operating at a distinct frequency, 13.56 MHz here, are fabricated on different substrates and it is shown that the Q factor and dimension of the TTP SSRC antenna could be controlled and adjusted based on the dielectric characteristics of the substrate. The new antenna prototype has a beneficial application to smart shelf applications in HF RFID.     

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。     

一种新型宽带双频段圆极化RFID读写天线

提出了一种新型宽带双频圆极化射频识别(RFID)读写天线,由上层的旋转对称折合振子和缝隙加载的方形贴片以及下层的紧凑型馈电网络构成。天线具有两个外部端口,分别激励低频0.9 GHz和高频2.45 GHz双频段的圆极化辐射。借助HFSS对天线进行了建模、仿真和优化,最后采用FR4板材制作天线实物并完成了试验测试。天线的外部尺寸为0.6λ0×0.6λ0×0.1λ0(λ0为0.9 GHz频点下的自由空间波长),测试结果表明,天线在低频段和高频段的-10 dB阻抗带宽和3dB轴比带宽分别为91.1%(4.9%)和87.8%(1.3%),频段内的峰值增益为5.48 dBic(3.63 dBic),最小轴比为1.1 dB(1.2 dB),在高低频段内,天线的辐射方向图对称稳定。该天线不仅能够满足全球通用型UHF频段(0.84~0.96 GHz)和ISM频段(2.4~2.5 GHz)RFID读写应用需求,而且具有低成本、易加工等优点,在物联网领域将具有很好的应用前景。     

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.      

Curved RFID tags for metallic gas cylinders

Presented is a radio frequency identification (RFID) tag antenna designed to fit around the neck of a small gas cylinder and capable of operation at the European and American UHF RFID bands. The design is readable from all directions in the plane of the cylinder neck and is mounted on cheap synthetic rubber (neoprene) of thickness 2 mm with dimensions of 125 x 20 mm. The tag antenna was conjugally matched to the complex impedance of the transponder IC chip.     

A novel circularly polarized reader antenna design for UHF RFID applications

Wireless Networks - In this article, a novel ultra-high frequency radio frequency identification (UHF RFID) reader antenna is proposed and experimentally investigated. The proposed RFID antenna...     

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...     

Broadband UHF RFID tag antenna with a pair of U slots mountable on metallic objects

A broadband ultra-high frequency radio frequency identification (UHF RFID) tag patch antenna with a pair of U slots is presented. By embedding a pair of U slots on the patch, a new resonant mode adjacent to the origin mode is excited and a broadband characteristic is achieved. The measured half-power bandwidth of the proposed antenna is 133 MHz and it covers all UHF RFID frequency bands. Measurement results show that the proposed antenna can work on metallic objects of different sizes in both North America and Europe bands.