UHF RFID Tag Research Articles

Design and Evaluation of an RFID Localization System based on Read Count

In this paper, we propose a new robust algorithm to improve the localization accuracy without using additional materials. This algorithm is based on a probabilistic approach which only uses the read count (number of detection) of reference and target tags. The localization is performed through two steps. The first step consists of estimating a local position of object tags in a given zone, while in the second step, all estimated local positions are used to calculate one global position. Furthermore, a complementary study concerning the influence of reference tags positions, the movement nature and the coverage of the work area is presented and discussed. For the proof of concept, a series of tests were elaborated with the proposed localization system created comprising conventional passive EPCglobal Class-1 Gen-2 UHF RFID tags, a commercial UHF RFID reader and a laptop. Measurements are carried out in an indoor environment where the 5.5 m×1.25 m measurement zone was placed on drywalls. The experimental results show that the present algorithm gives higher localization accuracy than the conventional ones.

Modeling and Design of a Compact Metal Mountable Dual-band UHF RFID Tag Antenna with Open Bent Stub Feed for Transport and Logistics Fields

Modeling and Design of a Compact Metal Mountable Dual-band UHF RFID Tag Antenna with Open Bent Stub Feed for Transport and Logistics Fields

Trajectory-Tracking of UHF RFID Tags, Exploiting Phase Measurements Collected From Fixed Antennas

In this article we propose a novel method for tracking a moving UHF RFID tag in 3D space. The tag moves in an area monitored by at least two antennas fixed at known locations. Phase measurements from each antenna are collected. Assuming a grid of N initial positions, we calculate N possible trajectories, by deriving closed form expressions, exploiting only the phase measurements collected by each antenna separately. Then, using the measured phase-difference from each antenna-pair, a hyperbola's branch on which the tag must be located is calculated. We evaluate the distance of each trajectory from the hyperbolas. Finally, we select the trajectory that minimizes the distance. Experimental results, conducted with a SLAM (Simultaneous Localization and Mapping)-enabled robot show a mean error less than 20cm with estimations derived in the order of ms. Compared to prior art, the proposed method does not assume neither knowledge of the trace, nor of the initial position of the tag. Furthermore, it accomplishes high accuracy at reduced computation time.

ShakeReader: 'Read' UHF RFID using Smartphone

UHF RFID technology becomes increasingly popular in stores, since it can quickly read a large number of RFID tags from afar. The deployed RFID infrastructure, however, does not directly benefit smartphone users in stores, mainly because smartphones cannot read UHF RFID tags or fetch relevant information. This paper aims to bridge the gap and allow users to 'read' UHF RFID tags using their smartphones, without any hardware modification to either deployed RFID systems or smartphone hardware. To ‘read’ an interested tag, a user makes a pre-defined smartphone gesture in front of an interested tag. The smartphone gesture causes changes in 1) RFID measurement data captured by RFID infrastructure, and 2) motion sensor data captured by the user's smartphone. By matching the two data, our system (named ShakeReader) can pair the interested tag with the corresponding smartphone, thereby enabling the smartphone to indirectly 'read' the interested tag. We build a novel reflector polarization model to analyze the impact of smartphone gesture to RFID backscattered signals. We enhance the basic version of ShakeReader [6] by improving its performance in densely deployed scenarios. Experimental results show that ShakeReader can accurately pair interested tags with their corresponding smartphones with an accuracy of >96.3%.

Development and Validation of an Autonomous Radio-Frequency Identification Controlled Soaking System for Dairy Cattle

HighlightsThe high variation on how dairy cows experience heat stress opens the space for individual heat abatement options.We developed an UHF-RFID activated soaking system for dairy cattle and validated it statically and dynamically.Percentage of soaker activations was moderate when validated statically and very high when validated dynamically.Future research should validate the system using dairy cows and evaluate effects on physiology and behavior.Abstract. This study aim was to develop and validate a radio-frequency identification (RFID) controlled cattle soaking system for use in dairy cattle. The autonomous system was composed of a Raspberry Pi microcontroller, an ultra-high frequency (UHF) RFID system, a temperature-humidity sensor, and a water soaker. The system was developed and programmed to identify and tailor heat stress abatement to dairy cattle. The validation of the system was divided into static and dynamic phases. During the static phase, five UHF-RFID tags were statically placed 5 times in 11 points of interest on a ranging from 0 to 150 cm of the antenna. During the dynamic phase, 10 tags were moved 10 times each from 150 cm to the right (closer to the barn) to 150 cm to the left (further from the barn) of the center of the antenna mimicking a cow’s walking speed. During the static validation, the percentage of successful readings was moderate (MEAN±SD; 77.8±30.1%). We found that the distance from the antenna affected the percentage of successful readings (P<0.01), it was 100% up to 60 cm from the antenna and static readings were less successful from 120 cm left up to 90 cm to the right of the center of the antenna. During the dynamic validation, the percentage of successful readings was very high (96.0±7.0%). These results suggest that the autonomous soaker system seems to be able to detect cows in movement underneath the system. Future research should validate the system using live dairy cows. Keywords: Automation, Heat stress, Raspberry Pi, RFID.

Next Generation Auto-Identification and Traceability Technologies for Industry 5.0: A Methodology and Practical Use Case for the Shipbuilding Industry

Industry 5.0 follows the steps of the Industry 4.0 paradigm and seeks for revolutionizing the way industries operate. In fact, Industry 5.0 focuses on research and innovation to support industrial production sustainability and place the well-being of industrial workers at the center of the production process. Thus, Industry 5.0 relies on three pillars: it is human-centric, it encourages sustainability and it is aimed at developing resilience against disruptions. Such core aspects cannot be fully achieved without a transparent end-to-end human-centered traceability throughout the value chain. As a consequence, Auto-Identification (Auto-ID) technologies play a key role, since they are able to provide automated item recognition, positioning and tracking without human intervention or in cooperation with industrial operators. Although the most popular Auto-ID technologies provide a certain degree of security and productivity, there are still open challenges for future Industry 5.0 factories. This article analyzes and evaluates the Auto-ID landscape and delivers a holistic perspective and understanding of the most popular and the latest technologies, looking for solutions that cope with harsh, diverse and complex industrial scenarios. In addition, it describes a methodology for selecting Auto-ID technologies for Industry 5.0 factories. Such a methodology is applied to a specific use case of the shipbuilding industry that requires identifying the main components of a ship during its construction and repair. To validate the outcomes of the methodology, a practical evaluation of passive and active UHF RFID tags was performed in an Offshore Patrol Vessel (OPV) under construction, showing that a careful selection and evaluation of the tags enables product identification and tracking even in areas with a very high density of metallic objects. As a result, this article serves as a useful guide for industrial stakeholders, including future developers and managers that seek for deploying identification and traceability technologies in Industry 5.0 scenarios.

Wearable Metasurface-Enabled Quasi-Yagi Antenna for UHF RFID Reader With End-Fire Radiation Along the Forearm

We present a quasi-Yagi antenna mounted on a periodic surface for a wearable UHF RFID reader operating in the UHF RFID frequency band centered at 915 MHz. The periodic surface was co-optimized with the antenna to enhance the launching of surface waves to enable the end-fire radiation along the forearm so that a user can identify objects by pointing her/his hand towards them. In addition to the radiation pattern modification, the ground plane of the periodic surface serves the second purpose of isolating the antenna from the human body. We optimized the antenna in a full-wave EM simulator using a simplified cylindrical model of the forearm and in the simulation, it achieved the end-fire directivity of 5.9 dBi along the forearm. In the wireless testing, the quasi-Yagi antenna provided the read range of 3.8 m for a typical UHF RFID tag having 0 dBi gain when the reader’s output power was 32 dBm that corresponds with EIRP =0.56 W and SAR =0.191 W/kg in our simulations. Considering both, the RFID emission regulations with EIRP = 3.28 W or 4 W and the SAR limit of 1.6 W/kg averaged over 1 gram of tissue, the read range could be further enhanced for reader units with higher output power.

Recent Advances in Passive UHF-RFID Tag Antenna Design for Improved Read Range in Product Packaging Applications: A Comprehensive Review

Radio frequency identification (RFID) is a rapidly developing technology, and RFID sensors have become important components in many common technology applications. The passive ultra-high frequency (UHF) tags used in RFID sensors have a higher data transfer rate and longer read range and usually come in unique small and portable application designs. However, these tags suffer from significant frequency interference when mounted on metallic materials or placed near liquid surfaces. This paper presents the recent advancements made in passive UHF-RFID tag designs proposed to resolve the interference problems. We focus on those designs that are intended to improve antenna read range as well as scalability designs for miniaturized applications.

Patch Antennas with T-Match, Inductively Coupled Loop and Nested-slots Layouts for Passive UHF-RFID Tags

Patch Antennas with T-Match, Inductively Coupled Loop and Nested-slots Layouts for Passive UHF-RFID Tags

An UHF RFID tag characterization methodology including a low-Bcaosqsute rao,n Cdab rleoraw, S-ousa complexity SDR platform for information extraction

RFID concepts have been evolving for more than fifty years, nevertheless it was until the last decade that this technology settled as one of the leading commercial solutions being applied on, for example tracking, access management and document registration applications, among others. This technology has brought many benefits to the users, like automation processes, inventory time reduction and information transmission reliability. However, before commercializing the RFIDs, test and characterization procedures must be executed in order to provide the correct information to the user. Unfortunately, lack of characterization methodology standards, high cost and high-complexity test equipment are recurrently dis-advantages. This work presents an RFID characterization methodology that uses a low-cost and handy RF signal platform for Electronic Product Code (EPC) time extraction.

Corrigendum to “Wearable Passive E-Textile UHF RFID Tag Based on a Slotted Patch Antenna with Sewn Ground and Microchip Interconnections”

Corrigendum to “Wearable Passive E-Textile UHF RFID Tag Based on a Slotted Patch Antenna with Sewn Ground and Microchip Interconnections”

Low-profile folded dipole UHF RFID tag antenna with outer strip lines for metal mounting application

A metal mountable UHF RFID tag antenna with a low-profile folded dipole structure is proposed. It is fabricated on a single layer of polytetrafluoroethylene (PTFE) dielectric laminate. It is composed of two symmetrical C-shape resonators integrated with the outer strip lines. The IC chip's terminals are connected directly to the center of the C-shaped resonators. The outer strip lines are integrated with the C-shaped resonators, which function to lower the reflection coefficient so as to match the IC chip impedance. In particular, the outer strip lines increase the inductive reactance of the antenna impedance in order to realize IC chip impedance. The design has a simple structure, due to the fact that it lacks any metallic vias. Moreover, the gain of the tag antenna can be enhanced when positioned on a large metallic sheet. Installed on a $40$ $\times$ $40$ $cm^{2}$ metallic plate, the total gain of the proposed tag antenna is $3$ dB, with a maximum reading range of $5.77$ m, while it is $3.92$ m in free space. The simulation results were in excellent agreement with the fabricated design results.

Structure optimization of an ultrahigh frequency radio frequency identification tag thread based on the normal mode helix dipole antenna

This paper describes the design of a novel ultrahigh frequency radio frequency identification (UHF RFID) tag thread that mainly consisted of the common yarn and the normal mode helix dipole antenna. The linear dipole antenna for the UHF RFID tag thread was too long to miniaturize the tag. In order to maximize the read performance and miniaturize the size of the tag, the basic antenna structure parameters, such as the helical pitch and single arm length, were optimized by analyzing the radiation parameter S11 of the normal mode helix dipole antenna based on simulation experiments. The simulation experiments started with optimizing the single arm length to obtain the minimum of the S11 parameter at resonant frequency, then the helical pitch was further optimized to limit the resonant frequency to the UHF range. The simulation results showed the resonant frequency rises with an increase of helical pitch and declines with an increase of single arm length. Furthermore, a series of UHF RFID tag threads with good performance from the simulation cases were prepared, and the performance of the optimized tag was validated. Generally, the UHF RFID tag thread with optimized helix dipole antenna could reduce the axial length of the tag by 57% and improve the reading range by 500%, and its performance was greatly superior to that of the UHF RFID tag thread with the classical linear dipole antenna.

Range and Bearing Estimation of an UHF-RFID Tag Using the Phase of the Backscattered Signal

The narrow bandwidth of UHF RFID signals does not allow the direct measurement of the range between the reader and the tag. A Multi-Hypothesis Extended Kalman Filter is proposed in this paper to solve this issue, by fusing the phase measurements with the odometry readings of a mobile robot. While estimating the tag-reader distance, the proposed approach provides also an on-line estimation of the bearing of the tag. The knowledge of range and bearing is beneficial in positioning-based applications as in robotics, to develop algorithms for reaching and grasping a tagged object or to localize a robot using tags as anchors, or for solving a Simultaneous Localization and Mapping (SLAM) problem if positions of both tags and robot are unknown. A few steps are usually enough to obtain a univocal effective estimate of these quantities, as long as the robot is moving over a non-straight path. A comprehensive numerical analysis supports and assesses the theory.

Design of UHF RFID Tag Antenna For Food Quality

Design of UHF RFID Tag Antenna For Food Quality

Particle Swarm Optimization in SAR-Based Method Enabling Real-Time 3D Positioning of UHF-RFID Tags

This paper presents a particle swarm optimization (PSO) in synthetic aperture radar (SAR) methods to enable real-time 3D localization of UHF-RFID tags. The reader antennas are moved through a moving agent (e.g., unmanned aerial vehicle, unmanned ground vehicle, robot) and they collect several phase samples by resembling a synthetic array. Thanks to the PSO approach the 3D matching function of the SAR method can be calculated in a reduced number of points by keeping an acceptable localization error. A numerical analysis demonstrates the method applicability through a comparison with conventional SAR methods based on the exhaustive search (3D dense grid) of the maximum point. Localization performance is investigated when an agent is equipped with a single antenna moving along a 3D trajectory or with two reader antennas at different height running a planar trajectory. Then, an experimental campaign in indoor scenario with an RFID-equipped unmanned ground vehicle shows the method effectiveness in performing real-time 3D positioning with centimeter-order localization error.

Performance Analysis of a Compact UHF RFID Ceramic Tag in High-Temperature Environments

In this paper an experimental analysis of the effect of high temperature on the performance of a compact UHF RFID tag is described and discussed. The tag is designed to be integrated into small cavities carved out of metal objects to identify themselves during the entire fabrication and assembly line. Since the UHF RFID tag is applied just after the die casting operations needed to model the metal component, it must be robust to high temperature manufacturing environments and processes. Tests demonstrated a significant chip input impedance variation by increasing the surrounding temperature, with a consequent read-range reduction. However, the considered ceramic tag can be detected at a satisfactory distance of 30 cm when employed with temperatures so high as up to 120°C.

Protecting Wearable UHF RFID Tags With Electro-Textile Antennas: The challenge of machine washability

Ultrahigh frequency radio-frequency identification (UHF RFID) tags have shown enormous potential in wearable applications for sensing human vital signs. However, the integration of UHF RFID tags in clothing to achieve machine washability remains a challenge. In this study, we investigated different ways of protecting wearable UHF RFID tags with electro-textile antennas against repeated washing. We replaced the antennas of commercial UHF RFID tags with the antennas made from a silver-coated fabric. Twenty-three types of methods, including five integrated circuit (IC)-protection methods and seven fixation/cover methods, were compared, with each having ten identical samples. The 230 samples underwent 20 cycles of machine washing and drying, and the changes in received signal strength indicator (RSSI) and the number of failed tags after washing were recorded and analyzed statistically. We found that 1) water penetration does not have a negative impact on tag functionality, therefore, being waterproof is not a requirement for the coating material; 2) heat-bond hem taping is the most efficient IC protection method; 3) heat and high pressure is effective to improve tag endurance; and 4) fusible interlinings and ironing, used in traditional garment production, can be effective.

Near-Field HF-RFID and CMA-Based Circularly Polarized Far-Field UHF-RFID Integrated Tag Antenna

This research proposes an integrated high-frequency (HF) and ultrahigh-frequency (UHF) passive radio frequency identification (RFID) tag antenna for near-field (13.56 MHz) and far-field (920–925 MHz) communication. This tag antenna is advantageous for the applications with lossy material in the near-field communication and mitigates polarization loss in the far-field communications. The HF-RFID tag antenna is of square spiral structure, and the circularly polarized UHF-RFID structure consists of a square loop radiator with cascading loop feeding and shorted stub. The structure of HF-RFID tag antenna situated inside the circularly polarized UHF-RFID tag can avoid the significant effect of the near-field magnetic coupling from the square loop. The UHF-RFID tag antenna is realized by using characteristic mode analysis for wideband circular polarization. The HF-RFID structure is conjugate-matched with NXP NT3H2111 chip, and the UHF-RFID structure is conjugate-matched with NXP G2X chip. Simulations were carried out, and an antenna prototype was fabricated. The experimental results reveal that the radiation pattern of UHF-RFID tag antenna is bidirectional with a gain of 0.31 dBic. The impedance bandwidth covers the frequency range of 903–944 MHz, and the axial ratio in boresight direction at 922.5 MHz is 1.67 dB, with the axial ratio bandwidth over 863–938 MHz. The maximum near-field and far-field reading ranges are 4.9 cm and 8.7 m. The proposed integrated dual-band passive tag antenna is operationally ideal for HF-RFID and UHF-RFID applications.

A differential low power wake-up circuit based on systematic offset for BAP UHF RFID tag

This paper presents a wake-up circuit for battery-assisted passive (BAP) RFID applications. The circuit is composed by a differential envelope detector and a comparator with a systematic offset. The differential RF signal envelope detector and the comparator are designed to increase the wake-up circuit sensitivity and to have low power consumption, improving battery lifetime. The wake-up circuit was designed and implemented in standard CMOS 0.18 µm process as part of an UHF RFID battery-assisted passive system, achieving a sensitivity of − 31 dBm and consuming only 150 nA.