Broadband CPW-fed folded-slot monopole antenna for 5.8 GHz RFID application

A folded slot is introduced to expand the impedance bandwidth and miniaturise the size of a coplanar waveguide (CPW)-fed patch monopole antenna for radio frequency identification (RFID) applications. The designed antenna, which, including ground plane, is only 13 mm in height and 11 mm in width, can operate at the 5.8 GHz band with measured impedance bandwidth and average antenna gain of 30% and /spl ges/5 dBi, respectively, and also conical radiation patterns. These properties make the antenna suitable for RFID tags.     

用于UHF频段的RFID波束扫描阵列天线设计

为了扩大射频识别系统阅读范围和提高识别效率,设计了一款应用于多标签高效读取的射频识别( RFID)波束扫描阵列天线。采用空气层结构设计出增益值为6 dBi的圆极化天线阵元并组成2×2平面天线阵,使用开关线型移相器与威尔金森(Wilkinson)功分器设计出天线馈电网络,并使用现场可编程门阵列(FPGA)模块控制阵元间相位变化,实现波束30°偏转。整体模型尺寸为350.0 mm×350.0 mm×5.7 mm,分别使用微波暗室、射频网络分析仪以及连接RFID阅读器测试,表明天线实现了4个方向波束偏转以及识别多个标签。     

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.     

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 microstrip antenna with U and T slots for 2.45/2.41 GHz RFID tag

A novel single-layer passive RFID tag antenna for the resonant frequency 2.45/2.41 GHz using a square microstrip patch with a pair of U and T slots is proposed, which is suitable for attaching to metallic objects. The proposed antenna was fabricated with a thin copper layer printed on a thin lossy FR4 substrate for low-cost production. The dimensions of the proposed antenna are around 35 times 35 mm. The antenna shows near-linear phase characteristics, 250 MHz bandwidth under the condition of voltage standing-wave ratio less than 2 and it covers all RFID microwave bands. The gain of the proposed antenna is 2.0 2.2 dBi for worldwide RFID microwave bands. Half-power bandwidth is about 108.     

Planar inverted-F antenna for radio frequency identification

A small and low-cost antenna solution for radio frequency identification (RFID) tags is presented. The impedance of the antenna is designed to match directly to the impedance of the RFID microchip. Also, the impedance of the antenna is immune to the platform. Thus, the antenna is applicable in many different environments. The design and measurement results are reported and discussed.     

一种UHF频段RFID阅读器天线的小型化设计

采用1／4波长微带贴片以缩小天线面积,利用商业软件Ansoft HFSS10．0进行设计仿真和优化,成功研制了一款可用于UHF频段（915MHz）RFID读写器的小型化微带天线。经过实际测试,天线在工作频段内性能优良,驻波比FSWR〈2时阻抗带宽达到30MHz。贴片天线的尺寸与性能完全满足手持RFID阅读器的需求。     

远距离RFID读写天线的研究

自动识别技术是将信息数据自动识读、自动输入计算机的一种重要方法。接触式识别易受恶劣环境影响且易受机械磨损,而射频识别（RFID）技术以非接触性解决卡中无源和免接触等难题。通过研究射频天线各种性能参数,提出一种远距离RFID读写天线的设计优化方法,使频率为13．56MHz,遵循ISO15693协议的RFID读写器有效读写距离拓展到30cm左右．实现RFID读写器的远距离读写功能。     

一种小型UHF RFID读写器天线设计

基于RFID系统对天线的要求,提出了一种适用于UHF频段上的RFID读写器天线。该天线采用背馈馈电方法,通过在分形结构上采用非对称矩形切角来实现天线的小型化和圆极化。利用电磁仿真软件分析了天线性能,仿真与测试结果吻合良好。     

基于多项式的弯折偶极子射频识别标签天线阻抗预测研究

在解决射频识别(RFID)标签天线设计中阻抗计算速度慢的问题的过程中,针对其中较为复杂的阻抗耦合情况,该文提出一种基于多项式的弯折偶极子RFID标签天线阻抗预测方法.首先使用基于天线尺寸的阻抗变换与线性化假设建立模型假设;然后在具体的天线结构中收集数据并进行相关性分析与回归拟合验证假设正确性;最后实验验证使用该方法进行的阻抗预测相对于计算机仿真的准确性、高效性与普适性.试验结果表明,使用该方法替代计算机进行弯折偶极子RFID标签天线阻抗计算时,其预测阻抗相对于计算机仿真结果在保持较高预测准确率的同时极大地缩短了阻抗计算时间,同时该方法在中国应用频段上针对不同弯折次数的弯折偶极子RFID标签天线仍然适用.     

基于多项式的弯折偶极子射频识别标签天线阻抗预测研究

在解决射频识别(RFID)标签天线设计中阻抗计算速度慢的问题的过程中,针对其中较为复杂的阻抗耦合情况,该文提出一种基于多项式的弯折偶极子RFID标签天线阻抗预测方法.首先使用基于天线尺寸的阻抗变换与线性化假设建立模型假设;然后在具体的天线结构中收集数据并进行相关性分析与回归拟合验证假设正确性;最后实验验证使用该方法进行...     

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。     

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.

     

射频识别贴片天线研究

近年来,自动识别方法在许多服务领域,诸如货物采购与分配、商业贸易、生产制造和物流等领域中,得到了快速地普及和推广。自动识别的任务和目的是提供关于个人、动物和商品的信息。自动识别系统克服了标签存储容量小和不能改写的缺点。自动识别系统在数据载体与一个所属阅读器之间进行非接触式传输。根据自动识别系统使用的能量和数据传输方法,我们把非接触式识别系统称为RFID 系统。RFID 系统是通过阅读器与标签之间的天线之间交换能量来读取数据的。常用于RFID 系统中的天线有偶极天线、Yaugi-Uda 天线、片状或微带天线和缝隙天线。     

基于BiLSTM代理模型的RFID标签天线快速多目标设计

为快速完成超高频(UHF)标签天线多目标设计,构建了基于双向长短期记忆(BiLSTM)神经网络的新型天线性能预测代理模型,并使用带精英策略的非支配排序遗传算法(NSGA-Ⅱ)配合静态惩罚对RFID标签天线进行多目标寻优.首先按照RFID标签天线延伸的趋势将天线结构序列化并依次输入BiLSTM网络结构,结合响应集训练出适...     

Dual-band fractal shape antenna design for RFID applications

A compact printed dipole antenna is proposed for radio frequency identification (RFID) applications. It consists of a combination of two kinds of fractal shapes with the aim of reducing antenna size. To ensure conjugate matching with the essentially complex impedance of the electronic chip directly embedded into the radiator, a double T-match structure is used. The antenna has been designed and optimised to cover the bi-band for the passive RFID tag at 915 MHz and 2.4 GHz. Details of the proposed antenna design and measured results are presented and discussed.     

远距离RFID读写天线的研究

自动识别技术是将信息数据自动识读、自动输入计算机的一种重要方法。接触式识别易受恶劣环境影响且易受机械磨损,而射频识别（RFID）技术以非接触性解决了卡中无电源和免接触等难题。通过对射频天线各种性能参数的研究,分析出了远距离RFID读写天线的设计优化方法．使工作频率为13．56MHz．遵循ISO15693协议标准的RFID读写器有效读写距离拓展到30cm左右,实现了RFID读写器的远距离读写功能。     

RFID sensors based on ubiquitous passive 13.56‐MHz RFID tags and complex impedance detection

Passive radio frequency identification (RFID) sensors are attractive in diverse applications where sensor performance is needed at a low cost and when battery‐free operation is critical. We developed a general approach for adapting ubiquitous and cost‐effective passive 13.56‐MHz RFID tags for diverse sensing applications. In developed RFID sensors, the complex impedance of the RFID resonant antenna is measured and correlated to physical, chemical, or biological properties of interest. In contrast to known wireless sensors, developed RFID sensors combine several measured parameters from the resonant sensor antenna with multivariate data analysis and deliver unique capability for multianalyte sensing and rejection of environmental interferences with a single sensor. Theoretical calculations and experiments in an anechoic chamber demonstrate that the developed RFID sensors are immune to common electromagnetic interferences and the sensor/reader system operates within regulated emission levels. Performance of developed RFID sensors is illustrated in measurements of toxic industrial chemicals (TICs) in air with the detection limit (DL) of 80 parts per billion and in a non‐invasive monitoring of milk spoilage. Sensors selectivity is demonstrated in the detection of different vapors with individual sensors. Copyright © 2008 John Wiley & Sons, Ltd.     

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.      

超高频RFID小型化读写器天线设计

提出了一款应用于超高频段(Ultra High Frequency,UHF)(912 ~935 MHz)的射频识别(RFID)读写器圆极化单层结构微带天线,基板采用FR4 板材达到价格低廉、辐射贴片采用开槽的结构实现小型化、接地板采用开槽结构提高天线的增益,该天线实现了小型化设计,满足了天线的设计要求。利用三维电磁仿真软件对天线模型进行了分析,仿真与测试结果吻合良好。天线测试结果表明:回波损耗小于-10 dB 的阻抗带宽为25 Hz(910 ~ 935 MHz),轴比(AR)小于3 dB的带宽为21 MHz(914 ~935 MHz);在UHF 频段内,读写器天线的最大增益为-1.2 dB,所以本天线能满足我国射频识别读写器的应用要求,具有良好的应用前景。