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关键词： CMOS   D Flip-flop   Full Swing Gate Diffusion Input (FSGDI)   RFID Reader   Transistor Optimization  

摘要： CMOS technology, commonly used in RFID circuits, faces limitations in power efficiency and chip size. This study optimizes the D Flip-Flop in RFID readers using Full Swing Gate Diffusion Input (FSGDI) with added buffers to reduce transistor count, power consumption, and delay, enhancing system performance. FSGDI achieves a stable output voltage and the lowest power consumption of 32.74 mu W, reducing power by 84.91% with a lower delay of 0.15 ns and 3.3V compared to CMOS. The D-flip-flop with FSGDI integration proposed in this study is beneficial for improving power efficiency and signal stability in RFID readers.

关键词： Antenna measurements   Artificial intelligence   Semiconductor device measurement   Continuous wavelet transforms   Chipless RFID   Training   Testing   Radiofrequency identification   Phase measurement   Data models   Chipless radio frequency identification (RFID)   classification   continuous wavelet transform (CWT)   convolutional neural networks (CNNs)   filtering   inverse Fourier transform (IFT)   machine learning  

摘要： In this work, we propose a novel approach for the detection of chipless radio frequency identification (RFID) signals. The method is based on the application of transformations to the measurement, in conjunction with the utilization of Artificial Intelligence (AI) algorithms. In the initial stage of the process, frequency-related features are measured. Subsequently, a time-frequency representation of these measurements is generated through the application of the inverse Fourier transform (IFT), a time-gating strategy, and the continuous wavelet transform (CWT). The resulting representation is then used as input to a shallow convolutional neural network (CNN), which is able to learn complex patterns while being able to generalize to new measurements. Furthermore, the proposed scheme incorporates a filtering process, based on the probabilities derived from the model, to filter out low-confidence predictions. To assess the performance of the proposed method, we consider a population of 16 tags. We collected 4800 measurements for the training phase and 2400 measurements for the testing phase in a real-world environment. These measurements are recorded on different days and within a distance range of 50-140 cm from the tag to the antenna. The proposed method exhibited accuracies of 94% in the 110-140 cm range, 99% in the 80-110 cm range, and 100% in the 50-80 cm range, showcasing its suitability for chipless RFID detection. All the code and datasets used in this work are publicly available on GitHub and the IEEE dataport, respectively.

摘要： Cashierless stores rely on computer vision and RFID tags to associate shoppers with items, but concealed items placed in backpacks, pockets, or bags create challenges for theft prevention. We introduce a system that turns existing RFID tagged items into material sensors by exploiting how different containers attenuate and scatter RF signals. Using RSSI and phase angle, we trained a neural network to classify seven common containers. In a simulated retail environment, the model achieves 89% accuracy with one second samples and 74% accuracy from single reads. Incorporating distance measurements, our system achieves 82% accuracy across 0.3–2m tag to reader separations. When deployed at aisle or doorway choke points, the system can flag suspicious events in real time, prompting camera screening or staff intervention. By combining material identification with computer vision tracking, our system provides proactive loss prevention for cashierless retail while utilizing existing infrastructure. © 2025, CC BY.

关键词： harmonic tag   dual-band   dual-polarized   doubler circuit   nonlinear circuit   annular ring antenna   RFID  

摘要： Radio frequency identification (RFID) technology has gained significant attention in various industry sectors due to its potential for efficient inventory management, asset tracking, and object localization. Different RFID technologies are available;resorting to harmonic signals is currently less used but, recently, has gained interest in research activity. In this study, we present the design, prototype realization, and performance evaluation of a dual-band dual-polarized harmonic tag. The tag incorporates a dual-band matching circuit utilizing a zero-bias Schottky diode HSMS-2850 connected to a perturbed annular ring patch antenna. The antenna, in fact, is able to radiate in cross-polarization at the higher frequency. Through a comprehensive design methodology, including simulation optimization and prototype fabrication, we demonstrate the successful implementation of the tag. Measurements to validate the impedance matching properties, radiation patterns, and backscattering capability of the tag are also shown.

关键词： circular polarization   dual band   electromagnetic band gap structures   metasurface   RFID  

摘要： This article proposes a hexagonal shaped circularly polarized (CP) antenna at ultra-high frequency (UHF) for radio frequency identification (RFID) and X-band applications. Initially, the antenna operates only in X-band and to convert this CP dual-band antenna asymmetric ground plane and four electromagnetic band gap structures are employed. A metasurface consisting of two complementary metamaterial structures is positioned above the patch at a 9 mm distance to enhance the gain and impedance bandwidth in both the bands. The presented antenna whose electrical dimension 0.48 lambda g x 0.48 lambda g x 0.02 lambda g achieves an impedance bandwidth of 796 MHz and of 4.24 GHz in UHF-RFID and X-band spectrum, respectively. The proposed antenna achieves circular polarization and has a bandwidth of 995 MHz and 796 MHz which spans 2.28-3.28 GHz and 10.44-11.24 GHz, respectively, with a 3 dB axial ratio. In addition to these, a stable radiation characteristic with an average gain of 6 dBi at both 2.45 GHz and 11.21 GHz are achieved which makes it suitable for RFID based real time logistic warehousing applications.

关键词： Thick shell Cu@Ag particle   Sintering   Conductive ink   RFID  

摘要： This paper introduces a method to synthesize thick-shell Cu@Ag particles, with nanorod-shape silver wrapped on the copper surface after substitution and reduction reactions. The average size of silver nanorods is less than 50 nm and that of the copper particles is about 1 mu m. The surface morphology, structure, and sintering properties of Cu@Ag particles were characterized in detail. The results show that the sintering temperature of thick-shell Cu@Ag is 127.5 degrees C, which is lower than that of Cu@Ag particles covered with island-shape and block-shape silver nanoparticles. The conductive ink was prepared by mixing it with resin paste, and the bulk conductivity of the conductive paste under different sintering conditions was investigated. The optimal -process parameters were chosen to conduct the printing of radio frequency identification (RFID) antennas. The farthest reading distances achieved by the ultra-high frequency RFID (UHF RFID) and the high-frequency RFID (HF RFID) were 9.4 m and 3.5 cm, respectively, which have good prospect of practical application.

关键词： RFID   IPS   IIoT   smart wheelchair  

摘要： A new Radio-Frequency Identification (RFID) indoor positioning system (IPS) has been developed to operate in environments where the Global Positioning System (GPS) is unavailable. Traditional RFID tracking systems, such as anti-theft systems in clothing stores, typically work within close proximity to exit doors. This paper presents a novel RFID IPS capable of locating and tracking passive RFID tags over a larger area with greater precision. These tags, costing approximately EUR 0.10 each, are in the form of small stickers that can be attached to any item requiring tracking. The proposed system is designed for an autonomous wheelchair, built from scratch, which will be identified and monitored using passive RFID tags. Our new RFID IPS, with a 12 m range, is implemented in this "smart" wheelchair.

关键词： 射频识别   温敏膜   碳纳米管   二氧化钛   接收信号强度  

摘要： 针对现有管道温度检测技术存在的安装复杂、灵敏度不足及有线传输等问题，本研究提出了一种基于碳纳米管-二氧化钛/壳聚糖复合温敏薄膜的柔性超高频射频识别（radio frequency identification，RFID）标签传感器，实现了管道温度的非接触式无线监测。该传感器通过将具有温度响应特性的碳纳米管-二氧化钛/壳聚糖复合薄膜沉积于标签辐射片表面，利用温度变化对标签信号的影响，建立接收信号强度（received signal strength indicator，RSSI）与温度之间的定量关系模型。实验研究表明，该温敏薄膜可显著提升标签的温度响应特性，有效检测范围为25 °C -75 °C。相较于传统检测方法，本传感器具有两大技术优势：其一，柔性基板设计实现了与管道的共形贴附；其二，无线传输特性规避了布线施工的复杂性。研究结果表明，该无线温度传感系统在工业管道监测领域展现出良好的应用前景。

关键词： Radio frequency identification   Sustainable construction   Exploratory factor analysis   Fourth industrial revolution   Sustainable development and developing countries  

摘要： Purpose - This study aims to explore the critical application areas of radio frequency identification (RFID) technology for sustainable buildings. Design/methodology/approach - The quantitative research approach was adopted through a structured questionnaire administered to relevant stakeholders of construction projects. The data collected were analysed with the exploratory factor analysis, relative importance index (RII) and fuzzy synthetic evaluation (FSE). Findings - The study's results have categorised the crucial areas of application where construction industry stakeholders should focus their attention. These areas are divided into four categories: management technologies, production technologies, sensing technologies and monitoring technologies. The findings from the FSE indicate that monitoring technologies represent the most significant category, whereas management technologies rank as the least significant. Moreover, the RII analysis highlights that tools management stands out as the most important application of RFID, while dispute resolution emerges as the least significant RFID application. Practical implications - The study establishes the core areas of RFID application and their benefits to sustainable buildings. Consequently, it helps stakeholders (consultants, clients and contractors) to examine the RFID application areas and make informed decision on sustainable construction. Furthermore, it provides systematic proof that can aid the implementation of RFID in developing countries. Originality/value - The study provides an insight into the possible application areas and benefits of RFID technology in the construction industry of developing countries. It also developed a conceptual frame for the critical application areas of RFID technology in the construction industry of developing countries.

关键词： Sensors   Monitoring   Fabrics   Dielectrics   Substrates   Sensor phenomena and characterization   FCC   Antennas   Antenna measurements   Electronic healthcare   Antenna-based sensing   dielectric properties   dual-band   eHealth   hydration monitoring   low-cost sensors   multifabric applications   radio frequency identification (RFID) sensors  

摘要： Continuous monitoring of body fluids is essential to maintain health and prevent critical issues such as dehydration, especially among those engaged in physical activities, living in harsh environments such as warm climates, or belonging to vulnerable populations. Traditional hydration monitoring solutions often involved complex measurements, required body-worn devices, or relied on batteries, making them impractical for widespread use among the general population. However, the development of low-cost, noninvasive hydration monitoring technology that can be integrated into textiles, together with the generalization of the digital product passport (DPP), could play a crucial role in democratizing and enhancing eHealth. Building upon previous studies, this work delves into the use of ultrahigh-frequency (UHF) radio frequency identification (RFID) antennas as hydration sensors on various fabrics and frequency bands. After dielectric characterization of different fabrics when mixed with synthetic euhydrated and dehydrated sweat, we developed and evaluated different prototypes compatible with different fabrics, achieving a read range four times larger compared with previous works. In a controlled laboratory environment, we achieved 100% accuracy classifying between euhydrated and dehydrated sweat in fabrics with liquid concentrations greater than 50%. Furthermore, the improved classification method ensures compatibility with both the Federal Communications Commission (FCC) and European Telecommunications Standards Institute (ETSI) bands.