Development of a novel radio frequency identification chipless tag with multifrequency response

This article presents an innovative contribution, which is the design of a novel radio frequency identification chipless tag characterized by a reduced size and a multifrequency response. It consists of a microstrip grounded structure based on a circular patch coupled with meandered metal strip. The adopted approach is an encoding frequency approach that ensures a capacity of 20 data bits in the ultra wideband. The main aim of this contribution is to introduce a novel configuration resulting from the study of the classic principles of the chipless tag design. It focuses on the design of an encoding surface associated with the same shape having the role of the transmitter/receiver antenna in order to mainly gain time to work on another tag component. The tag is analyzed, optimized, and measured to validate its feasibility and to prove the possibility of its commercial application.     

无芯射频标签编码方式研究

无芯射频标签编码是射频识别技术中一项非常重要的技术。主要研究了基于蝶形无芯射频标签工作频率在2 GHz-10 GHz的雷达散射波的幅度或者相位,并对其相位或幅度采用PCM-△编码,是无芯射频标签编码的新方式。研究结果表明,该编码方式能够对紧凑的开槽标签结构进行有效编码,且编码方式灵活,扩充方便。     

A chipless RFID tag for smart temporal applications

A compact, robust, chipless radio frequency identification (RFID) tag is proposed. Resonant elements patterned in a concentric fashion encode data in the spectral domain employing frequency shift encoding. The proposed tag encodes 28.25 data bits over a miniscule physical footprint of 25 × 25 mm². The formulated scheme is demonstrated to be viable for encoding of temporal variables. The electromagnetic performance of the presented design is investigated for different laminates: Rogers RT/duroid® 5880 and Taconic TLX‐0. Multiple tag prototypes employing a variety of substrates are realized and evaluated for in‐laboratory performance. The proposed design is compared with existing work reported in literature. Code density of 4.52 bits/cm² has been successfully achieved. The tag design operates from 3.07 to 10.6 GHz and is readily realizable on flexible laminates. Smart retail, intelligent packaging, adaptive ticketing, and similar time‐related applications can be materialized using the proposed tag.     

Long read range and flexible UHF RFID tag antenna made of high conductivity graphene‐based film

An antenna made of a graphene‐based film with organic polyimide precursor of high conductivity 1.1 × 10⁶ S m^?1 and thickness 30 μm, operating in the ultrahigh frequency (UHF) band for radio frequency identification applications is presented in this article. The antenna is optimized to have a conjugate match to the impedance of the chip by tuning the design parameters. Tags are fabricated and tested using the designed antenna, which are shown to have realized gain above ?1.5 dBi and radiation efficiency beyond 90% in the whole UHF band from 860 to 960 MHz. The read range of proposed tag is greater than 12.3 m over the entire UHF band with a maximum value of 14 m at 920 MHz. In addition, the flexibility of the tags is demonstrated. After 2000 cycles of bending and stretching, the read range only decreases by 4.5 m comparing to the initial state at 915 MHz.     

A single sided dual‐antenna structure for UHF RFID tag applications

In this article, a dual‐antenna structure is presented for UHF RFID tag. The proposed structure is made of two L‐shaped strip antennas along with a cross‐shaped slot loaded patch. One antenna is exclusively used for receiving and harvesting full energy with complex conjugate of tag chip, whereas another used as backscatter to enhance maximum differential radar cross section with purely real input impedance, which results in the enhancement of read range. Further, electromagnetic band gap structure is used around the dual‐antenna structure to increase the gain which results in improved read range. The proposed antennas are fabricated and the S‐parameters are measured with the help of differential probe technique. Simulation and measurement results are found in good agreement. The performance of the proposed antenna is also investigated when it placed on different materials such as metal, wood, glass, and plastic. The study shows that the read range of antenna increases considerably when it is mounted on a metallic surface, while the maximum performance is observed when the antenna is attached on a glass surface with highest relative permittivity. © 2015 Wiley Periodicals, Inc. Int J RF and Microwave CAE 25:619–628, 2015.     

柔性标签弯曲及对RFID系统识读距离的影响研究

针对平面结构标签在使用过程中经常发生弯曲形变的问题,研究一种柔性标签发生圆弧形弯曲和垂直折叠形变时天线性能的变化以及对RFID系统识读距离的影响。介绍柔性标签天线的研究现状,分析影响RFID系统识读距离的关键因素,通过示意图阐述弯曲天线模型的建模方法,基于HFSS仿真分析阻抗、增益和辐射效率等的变化规律。通过实际测量验证了RFID系统识读距离的仿真结果及该方法的可行性。     

RFID tag antenna for ultra and super high frequency band applications

A novel dual‐band antenna for radio frequency identification tag is proposed for ultra high frequency (UHF: 915 MHz) and super high frequency (SHF: 2450 MHz) bands. The proposed tag antenna is a single sided dual‐antenna structure, designed on the grounded (metallic) dielectric substrate. The proposed tag antenna can be used on any kind of surfaces including metals without severe performance degradation due to its metallic ground plane. At UHF band, proposed tag antenna works as dual‐antenna structure. In the dual‐antenna structure, one antenna works for receiving and another for backscattering. Due to separate backscatterer, the maximum differential radar cross section improved and results in the enhancement of the maximum read range. Whereas at SHF band, proposed antenna works as conventional single antenna structure and during operations it switches between receiving and backscattering modes. The proposed antenna consists of a meandered line antenna and a rectangular patch antenna loaded with an F‐shaped and an inverted L‐shaped slots. The S‐parameters are measured by means of differential probe technique. Simulated and measured results are observed in good agreement. The read range is observed about 5 and 6 m at 915 and 2450 MHz, respectively. © 2016 Wiley Periodicals, Inc. Int J RF and Microwave CAE 26:640–650, 2016.     

Design of a compact size tag antenna based on split ring resonator for UHF RFID application

In this article, a new design of miniaturized split‐ring resonator antenna using a meander line technique with a simple impedance matching method applicable to UHF‐RFID tags is presented. The new approach is based on the integration of a meander line into the radiating element of SRR to reduce the electrical tag size and a theoretical demonstration to calculate the conjugate impedance matching and directly attach the antenna with the chip. The new SRR antenna, which is printed on the flexible substrate Arlon CuClad 250LX, is designed using Alien Higgs 3 RFID ASIC whose input impedance is 25‐j190. The prototype antenna has a low‐cost compact size (18.28 mm × 18.28 mm) with a read range higher than 4 m within the RFID UHF band and with a roughly 4.2‐m peak range at 915 MHz. As a proof of behavior, a tag prototype is fabricated and measured to operate at a UHF RFID band. Based on some works' results, an optimized design is obtained with a 48% size reduction compared with the classic split ring resonator antenna and with a good impedance matching the antenna with RFID ASIC without the need for any external matching network.     

Compact meandered RFID tag antenna with high read range for UHF band applications

In this work, a compact, long read range, and an efficient spiral loop structure coupled tag antenna is proposed for UHF‐RFID applications. Meandered line element is inductively coupled to spiral loop for matching its input impedance to Higgs‐4 chip. Equivalent circuit of antenna is extracted to analyze its working mechanism in the operating band. Experimental characterization validates the performance of proposed tag antenna in free space and on cardboard sheet in terms of read range, tag sensitivity, and differential radar cross section with an EIRP of 3.28 W. The measured radiation pattern of the tag is found to be omnidirectional in H plane and figure of eight in E plane. The tag's read range is measured on objects like fiber, wood, plastic, and glass in outdoor scenario to study its environment tolerance. The tag antenna has volumetric size of 1736 mm³ and read range of 13.6 m in US RFID band.     

基于RFID的虚拟标签算法研究与改进

针对室内定位算法VIRE的定位精度,特别是邻近边界目标的定位精度较低的问题,以RFID标签定位为研究基础,从改变VIRE算法中虚拟标签的插值方式和在边界上加入虚拟标签两个方面进行研究和改进。使用拉格朗日插值代替VIRE算法中的线性插值方式,使虚拟标签的数据更加接近实际环境值;在边界上加入虚拟参考标签能增加已知标签数,防止在计算待定位标签坐标时引入误差标签。实验结果表明,标签定位精度有了明显提高,整体能提高了35%,邻近边界标签定位精度提高较大,可达到50%以上。     

A broadband radar cross section reduction metasurface based on integrated polarization conversion and scattering cancelation

In this paper, we proposed and demonstrated a broadband radar cross section (RCS) reduction metasurface by integrating polarization conversion and scattering cancelation. A broadband polarization conversion structure was designed based on split concentric ring. We used a 4 × 4 array of split ring structure and its mirror‐symmetric structure as the super‐cell units to construct a metasurface with chessboard structure. The metasurface can efficiently reduce the co‐polarization RCS for all azimuth angles of incident wave. The metasurface sample with optimized structure parameters was fabricated and measured. The measured 10 dB RCS reduction band of the metasurface is from 8.6 to 17.7 GHz.     

Ultra‐wideband radar cross‐section reduction using polarization conversion metasurface

In this paper, a novel ultra‐wideband (UWB) chessboard structured metasurface has been designed to realize the monostatic radar cross‐section (RCS) reduction. The unit has a periodic simple multi‐V‐shaped structure can convert linear polarized waves into their orthogonal polarized ones in an UWB ranging from 14.5 to 41 GHz. In addition, the RCS reduction of two kinds of chessboard structures which composed of the proposed unit are compared in this paper, and one of them has been fabricated and tested. Experiments and simulation results show that, under normal incidence of electromagnetic wave, it can achieve RCS reduction over 10 dB within an UWB of 20.5 GHz.     

基于有源RFID的极低功耗温湿度传感标签的设计

提出了可以显著降低功耗的有源RFID标签工作流程,设计出一种极低功耗的温湿度传感标签。该标签采用微控制器PIC24F16KA102为核心,以温湿度传感器SHT21S和射频收发芯片nRF24L01为外围器件,完成温湿度及电池电量信息的检测和发送。该有源标签在开阔场地的有效阅读距离可以达到80m左右,标签连续工作时的电池寿命为9年以上,具有体积小、寿命长等优点,可广泛应用于生产车间的温湿度监测、冷链物流、医疗系统、仓储物资管理等方面。     

Linearly tapered meander line broadband monopole tag antenna with T‐match for Ultra High Frequency Radio Frequency Identification applications

In this paper, a compact, broadband linearly tapered meandered monopole tag antenna for UHF‐RFID is designed and optimized using particle swarm optimization (PSO) algorithm. An inductive T‐match network is utilized for impedance matching with capacitive Higgs‐4 chip. The optimization goal of PSO was conjugate matching and in consequence the maximization of read range. Equivalent circuit of the proposed tag antenna is derived using ADS software to validate its impedance characteristics. The performance of the proposed tag in terms of tag power sensitivity, read range, realized gain, and differential radar cross section has been experimentally characterized. To check the tolerance of the designed tag to various object platforms, its read range performance is also verified on objects like wood, fiber, plastic, and so forth. Furthermore, read pattern of the proposed tag has been measured and found to have figure of eight in E‐plane and omnidirectional in H‐plane. Experimental results reveal that the proposed tag covers 865‐867 MHz (ETSI band, Europe) and 902‐928 MHz (FCC band, United States) both major RFID bands with a read range of 10 and 12 m, respectively. The proposed tag has 2060 mm³ of volumetric size with maximum measured readable distance of 12 m with EIRP of 3.28 W.     

Wideband and low profile polarization conversion meatasurface‐based circularly polarized slot antenna

The purpose of this study is to investigate the application of a polarization conversion meatasurface for constructing a low profile, wideband circularly polarized slot antenna, which consists of a new Polarization conversion metasurface (PCM)‐based square‐corner‐cut artificial magnetic conductor cell structure and a feeding slot antenna. PCM possesses two frequency points of polarization rotation (PR), produced by appropriately adjusting width between the two triangular metallic patches. A 39.3% (4.7‐7 GHz) of big PR band was realized through the combination of two neighboring PR frequency points. The impedance bandwidth of PCM based patch antenna was measured to be 43.5% (4.5‐7 GHz), with 17.2% (5.3‐6.3 GHz) of 3 dB axial ratio (AR) bandwidth and 0.045λ₀ of profile. It also generated 7.3 dBic of high broadside gain in operational bandwidth.     

Joint tracking and classification based on aerodynamic model and radar cross section

We present interacting multiple model regularized particle filter for the X-band active surveillance radar to jointly track and classify air threaten targets. The actual aerodynamic equations for flight are used as motion model, and automatic target classification is made possible by the inclusion of radar cross section in the measurement vector. Thus, tracking and classification are closely coupled, giving full play to the advantages of joint tracking and classification. The proposed methodologies show good performance according to simulations.     

RCS2D: A 2D MoM and FDTD‐based scattering simulator

A Java‐based, two‐dimensional electromagnetic (EM) scattering field simulator—RCS2D—is introduced. It enables one to explore EM wave—arbitrary object interaction under a plane wave illumination. RCS2D uses both method of moments and finite‐difference time‐domain models for both transverse magnetic and transverse electric polarizations. © 2013 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2013.     

Stretchable,flexible, and adherable polarization volume grating film for waveguide‐based augmented reality displays

We report a stretchable, flexible, and adherable polarization volume grating (PVG) film and propose a compact optical system for augmented reality displays based on it. The Bragg reflection band shift, deflection angle change, and the mechanical robustness under stretch‐release cycles of the PVG film are also investigated.     

Modeling and robust adaptive iterative learning control of a vehicle‐based flexible manipulator with uncertainties

In this brief, this paper deals with a robust adaptive iterative learning control (ILC) problem for a flexible manipulator attached to a moving vehicle with uncertainties. To begin with, considering the infinite dimensionality of the flexible distributed parameter system, a coupled ordinary differential equation and partial differential equation model is established without any discretization. Then, it is followed by a presentation of an adaptive ILC strategy, which can drive the vehicle and joint to the desired positions based on a proportional‐derivative feedback structure with unmodeled dynamics and external disturbances. The deformation of the flexible manipulator can also be suppressed simultaneously under the proposed control laws. By using Lyapunov's direct method, the stability of the closed‐loop system is demonstrated. The simulation results are provided to illustrate the effectiveness of the proposed control laws.     

Parameter estimation of the 2D‐GTD model and RCS reconstruction based on an improved 2D‐ESPRIT algorithm

The two‐dimensional estimating signal parameter via rotational invariance techniques (2D‐ESPRIT) algorithm is a classical method to estimate parameters of the two‐dimensional geometric theory of diffraction (2D‐GTD) model. While as signal‐to‐noise‐ratio (SNR) decreases, the parameter estimation performance of 2D‐ESPRIT algorithm is severely influenced. To solve this problem, a performance‐enhanced 2D‐ESPRIT algorithm is proposed in this article. The improved 2D‐ESPRIT algorithm combines the conjugate data with the original back‐scattered data and obtains a novel covariance matrix by squaring the original total covariance matrix. Simulation results indicate that the improved algorithm has a better noise robustness and a more stable parameter estimation performance than the classical ESPRIT algorithm and the classical TLS‐2D‐ESPRIT algorithm. To further validate the superiority of the improved 2D‐ESPRIT algorithm, reconstructed radar cross section (RCS) is presented in this article. Compared with the classical 2D‐ESPRIT algorithm, the proposed algorithm presents higher RCS fitting precision. Furthermore, the impacts of other factors on parameter estimation, such as matrix pencil parameters and paring parameters, are also studied in this article.