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关键词： Circular polarization  

摘要： In this paper, a novel cavity-backed slot-antenna (CBSA) antenna pair designed with shared-radiator is proposed for radio frequency identification (RFID) systems. The CBSA pair is co-circularly polarized, meanwhile exhibiting in-band full-duplex (IBFD) capability and good radiation pattern consistency in the RFID band. The near-field mode superposition method is employed to achieve isolation between the transmitting and receiving ports. Additionally, a patch is designed inside the cavity to reshape the original cavity’s electric field distribution, thus enhancing the mode superposition and improving isolation performance. Further regulation of the feeding ports’ positions and introduction of cross slots achieve the circular polarization. The proposed CBSA pair was fabricated and measured. The prototype achieves an overlapping bandwidth of 916.5–925.4 MHz, where the impedance matching, -20 dB decoupling, and -3 dB axial ratio criteria are simultaneously satisfied, effectively covering the RFID frequency range (920–925 MHz). Notably, the maximum decoupling level within this band reaches 27.4 dB. The proposed CBSA pair has advantages in compact size, co-circularly polarized and in-band full-duplex performance, and can serve as a good candidate for compact, high-performance RFID reader applications, and is well-suited for RFID systems requiring high-density target inventorying. © 1963-2012 IEEE.

关键词： Data accuracy  

摘要： In view of the problems in the existing methods such as large retrieval error, low data positioning accuracy, and long retrieval time, this paper proposes an intelligent retrieval method for book resources in smart libraries based on RFID. First, complete the rough extraction of the features of the book resources in the smart library. Then, set the length rule of book resource features, eliminate ambiguous data, determine the similarity of book resource features, and merge similar features through similar probability mapping. Finally, complete the feature data authentication, set the tag with RFID tag technology, locate the tag data location, build the book resource index tree, and determine the intelligent retrieval model. The test results show that the proposed method can reduce the intelligent retrieval error of book resources in smart libraries, improve the accuracy of data location, and reduce the retrieval time cost. Copyright © 2025 Inderscience Enterprises Ltd.

关键词： Effective permittivity   slot-type tag   patch-type tag   dual-polarization   polarization-independent   smart materials   humidity sensor   Effective permittivity   slot-type tag   patch-type tag   dual-polarization   polarization-independent   smart materials   humidity sensor  

摘要： This review paper presents comprehensive literature on passive chipless Radio Frequency IDentification (RFID) humidity sensor tags, including working principle, performance measures, and use cases. The RFID humidity sensor tag comprises of RF resonators for identification and separate resonators along with smart material for humidity sensing. The humidity sensor tags are effective permittivity-based sensors, where the smart material's effective permittivity changes with humidity. The change is recorded with different coding methods, whereas the sensitivity depends on both tag configuration and sensing material. Therefore, this paper emphasizes state-of-the-art tag configurations, approaches to designing RFID humidity sensor tags, and the properties of the humidity-sensitive material. Most of the RFID humidity sensors are designed based on the frequency coding method where coding capacity depends on the number of resonators, hence the overall size of the tag. Therefore, a variety of resonators like patch- and slot-types, along with their orientation with respect to linearly polarized reader antenna are discussed. The advantages of slot-type tags coated with humidity-sensitive material are highlighted in terms of dual-side readability, polarization-independent nature, higher data coding capacity, and better sensitivity. RFID humidity sensors will be beneficial for future Internet-of-things (IoT) applications.

关键词： Wireless communication   Training   Adaptation models   Cloning   Media Access Control   Graph neural networks   Robustness   Real-time systems   Security   Testing   RFID   graph neural network   cloning attack   real-time detection  

摘要： In the field of RFID systems, cloning attacks that replicate authentic tags to deceive readers pose a significant threat to corporate security, potentially leading to financial losses and reputational damage. Many existing solutions struggle to mitigate this threat without altering the Medium Access Control (MAC) layer protocols or integrating additional hardware resources, which are impractical adjustments for commercial off-the-shelf (COTS) RFID devices. This paper introduces an innovative system framework that leverages Graph Neural Network to detect RFID tag cloning attacks without the need to change the MAC protocols or add hardware resources. The system can automatically uncover implicit topological structures from RFID signal data and adaptively capture complex inter-signal relationships. By constructing dynamic graph and employing Graph Attention Network, this framework not only captures deep data correlations that traditional detection methods cannot identify but also demonstrates exceptional accuracy and robustness in experiments. Experimental results have proven that the framework maintains stable performance even when the training and testing data distributions are mismatched, as verified in both static and dynamic tag cloning attack scenarios. Furthermore, the framework effectively identifies anomalous behavior by comprehensively considering precision, recall, and F1 scores, especially when dealing with highly imbalanced datasets.

关键词： Time domain analysis  

摘要： Chipless Radio Frequency Identification (CRFID) systems have emerged as a cost-effective and scalable solution for various identification and tracking applications. However, multi-tag classification remains a significant challenge due to overlapping signal characteristics and the absence of on-chip processing, which hinders accurate tag differentiation, increases interference, reduces classification accuracy, and necessitates advanced signal processing techniques for reliable identification. This study presents a novel machine learning-based approach utilizing a Classifier Chain-AdaBoost (CC-AdaBoost) model to improve multi-tag classification accuracy. Un-like conventional methods that rely on calibration or background subtraction, the proposed approach directly processes raw time-domain signals, enabling efficient and accurate classification of multiple tags simultaneously. The model is evaluated on simulated CRFID data, achieving an overall accuracy of 85%. Performance metrics such as accuracy, Hamming loss, Jaccard score, and F1-score are analysed to assess both overall classification performance and label-wise evaluation. Results indicate that CC-AdaBoost effectively differentiates tag classes, particularly excelling in high-confidence classifications while maintaining a balance between precision and recall. This study demonstrates the feasibility of CC-AdaBoost for real-world CRFID applications and suggests potential improvements for optimizing multi-tag recognition in complex environments. © 2025, Electromagnetics Academy. All rights reserved.

关键词： Radiofrequency identification   Soil moisture   Sensors   Monitoring   Capacitance   Substrates   Soil measurements   UHF antennas   Permittivity   Dipole antennas   Battery-less   ultra high frequency radio frequency identification (UHF-RFID)   soil moisture monitoring   capacitive sensing   EM4152 RFID chip   interdigitated capacitor   IDC   wireless sensor   precision agriculture   volumetric water content (VWC)   sustainable agriculture  

摘要： Soil moisture monitoring is essential for optimizing irrigation strategies, enhancing crop yields, and conserving water resources in precision agriculture. Traditional sensing methods often rely on battery-powered devices, which require maintenance and periodic replacement. This work introduces a batteryless ultrahigh frequency radio frequency identification (UHF RFID) soil moisture sensor that leverages RFID technology and an interdigitated capacitor (IDC) for capacitive sensing. The proposed sensor integrates a meandered dipole antenna and an EM4152 RFID chip, enabling wireless monitoring of soil Volumetric Water Content (VWC) without the need for an external power source. The sensor's performance is validated through controlled soil moisture experiments, where capacitance readings are correlated with reference measurements from the commercial TEROS 10 soil moisture sensor. The sensor was tested and calibrated using three different soil types: sandy, clay, and a commercial combo substrate. The results demonstrate strong linear correlations with TEROS 10 measurements across all soil types, with coefficients of determination of R-2 = 0.9648 (sandy), R-2 = 0.9512 (clay), and R-2 = 0.9444 (combo). Furthermore, tests conducted at varying water contents and a read range of up to 3.5 meters validate the sensor's robustness across different soil conditions. The findings highlight the potential of battery-less RFID-based sensing for sustainable and maintenance-free soil moisture monitoring in agricultural applications.

关键词： Circular polarization  

摘要： In this letter, a dual-band rotational feed circularly polarized (CP) antenna array is proposed. The dual-band antenna element consists of two pairs of symmetric dipoles. The low-frequency CP radiation is achieved by the longer dipole pair, and the high-frequency radiation is mainly superimposed by the shorter dipole pair of the fundamental mode and the longer dipole pair of the higher-order mode. A compact and low-profile antenna array with a 1-to-4 rotational feeding network is introduced. The measured |S11| © 2002-2011 IEEE.

关键词： Radiofrequency identification   Standards   Companies   Ethics   Passive RFID tags   Wireless communication   Training   Recycling   Protocols   Investment   Circular economy   ethics   Internet of Things (IoT)   radio frequency identification (RFID)   traceability  

摘要： In a planetary context where natural resources, such as water, minerals, fossil fuels, and raw materials used for food and manufacturing, are increasingly overexploited to satisfy human needs, with increasingly worrying consequences for the environment and for future generations, new paradigms are emerging such as the circular economy. The aim is to identify new solutions for optimizing the use of resources and minimizing waste. In this context, RFID (Radio Frequency Identification) technology appears to be a relevant tool for many industrial sectors, as it can potentially track and identify an object throughout its life cycle. This article aims to reflect on the use and impact of RFID in the circular economy, highlighting key issues at stake. To provide a broader perspective, this discussion incorporates ethical and philosophical concepts.

关键词： RFID技术   智慧图书馆   图书定位导航  

摘要： 阐述RFID技术在高校智慧图书馆的应用现状，针对该技术在高校智慧图书馆应用中存在的成本较高、标准不统一、智慧建设不完善和读者使用不熟练的问题提出应对措施。

关键词： RFID天线   波束形成   大尺寸天线   近远场天线   多极化波束扫描  

摘要： 工业 4.0、工业物联网(Industrial Internet of Things,IIOT)与第五代移动通信系统(5th Generation Mobile Communication System,5G)的迅速发展对无线识别系统提出了高密度、高精度的需求。无线射频识别(Radio Frequency Identification,RFID)作为识别的关键技术,能够通过物体的独特特征实现精准识别,从而在通信、感知的基础上完成进一步的精细化管理。RFID读写器天线的性能则直接决定了系统的识别精度、识读范围与环境适应性,具有重要的研究价值。本文基于复杂应用场景开展了高精度识别RFID读写器天线的研究与设计实现,从大识读范围、高抗干扰特性、高重构特性三个维度进行高精度的天线性能的探索,并验证了天线在特定应用中的优异性能,主要创新点如下。 1.提出了一种基于角连接方式与多阶分形单元结构的大面积灵活扩展的近场天线。角连接方式使得天线能够具备在平面自由扩展的能力以及适应复杂场景的多种阵列形状的形成能力。通过多阶分形的单元结构,增加了近场磁场的强度与均匀性,提升了天线的近场读取距离。利用空气层的加载与基于行波电流的串馈阵列结构,减少了天线损耗,实现了大尺寸阵列的电流与磁场的均匀性,显著增加了阵列的识读面积。利用单元传输相位的优化,降低了阵列的远场辐射,获得了大尺寸下的低增益远场辐射方向图,具备抑制远场干扰的效果。1×8、2×4、3×3天线阵列测得的阻抗带宽均覆盖920-925 MHz频段,最大远场增益小于-8.6dBi,在360×360mm2以上的天线面积实现了至少57 mm的识读距离。与目前已发表的同类型天线相比,在近场读取距离不恶化的前提下,具有尺寸大、平面扩展灵活的显著优势。 2.提出了一种基于分段耦合的弯折四偶极子环与两入四出馈电网络的近远场可切换天线。通过分段耦合的微带线结构,抵消了传输线自身的相移,获得了强度均匀的表面电流分布。利用弯折、耦合结构的加载形成四偶极子环天线,实现了辐射结构的优化与强而均匀的近场磁场的产生。通过对两入四出馈电网络进行分析设计,实现了对于四天线双模式的相位定制与便捷的模式切换,使天线具备可重构特性。测得的天线在近场模式下的增益为-1.6dBic,形成差分的右旋圆极化辐射,在远场模式下的增益为3.7 dBic,形成定向的左旋圆极化辐射,且天线的端口隔离度高于22 dB,能够大幅度抑制两种模式下的互相干扰。近场模式下标签的识读范围至少为270 × 270 × 240 mm3。与目前已发表的同类型天线相比,具有近场模式识读范围大、识读距离远,以及近场、远场模式的端口隔离度高、增益差值大的显著优势。 3.提出了基于鱼骨形槽的平面多极化贴片与可重构馈电网络的远场多极化低剖面可重构波束扫描天线阵列。利用中心馈电的镜像对称的贴片结构,实现平面多极化辐射的产生与抗多径干扰的能力。利用鱼骨形槽与交指电容的加载,降低了谐振频率,提高了辐射效率。通过对贴片等效电路与表面电流的深入分析可实现贴片对于谐振频率与辐射效率的综合优化,给出了实现高极化纯度与高辐射效率的设计方法。利用可重构馈电网络实现0°、90°相位的切换,整体天线单元在维持低剖面性能的同时实现了多极化2 bit相位量化。8×8天线阵列在不同极化与波束状态下的测试阻抗带宽均覆盖5.63-5.94 GHz,最大增益为16.8dBi,剖面仅为1.827mm。天线在水平极化、垂直极化、45°极化、圆极化下的波束扫描范围为60°、50°、55°、30°。与目前已发表的同类型天线相比,在满足单馈电二维波束扫描的前提下具有多极化、低剖面的显著优势。