Ultra High Frequency Radio Frequency Identification Research Articles

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.

Recovery of collided RFID tags with frequency drift on physical layer

In a passive ultra-high frequency ( UHF ) radio frequency identification ( RFID ) system, the recovery of collided tag signals on a physical layer can enhance identification efficiency. However, frequency drift is very common in UHF RFID systems, and will have an influence on the recovery on the physical layer. To address the problem of recovery with the frequency drift, this paper adopts a radial basis function ( RBF ) network to separate the collision signals, and decode the signals via FM0 to recovery collided RFID tags. Numerical results show that the method in this paper has better performance of symbol error rate ( SER ) and separation efficiency compared to conventional methods when frequency drift occurs.

A Fast UHF RFID Localization Method Using Unwrapped Phase-Position Model

A novel ultrahigh-frequency (UHF) radio frequency identification (RFID) localization method is proposed in this paper, by which the location of a static passive tag can be easily obtained using a mobile RFID antenna. An unwrapped phase-position model with three parameters is built, and the location of the tag can be pinpointed through an ordinary nonlinear least-squares algorithm. The main advantage of this method is that it is cheap in computation cost compared with the existing grid-based methods. The experimental tests confirm that the proposed method can localize the RFID tags with a competitive computational efficiency and accuracy performance, i.e., millisecond-level computing time and centimeter-level location accuracy. The proposed UHF RFID localization method is well suited to the pervasive location-aware applications, searching RFID-tagged item in the intelligent warehouse by the mobile robot with an onboard RFID system, for example.

UHF RFID Sensor System Using Tag Signal Patterns: Prototype System

This letter presents a novel passive radio frequency identification (RFID) sensor prototype system in the ultrahigh frequency (UHF) range, which is based on the detection of fully controlled patterns of the backscattered transponder (tag) signals. The UHF RFID tag antenna itself is used as the sensing device. A custom-built sensor tag has been designed to monitor the water filling level of a canister (i.e., canister full or empty). The measurement results of the prototype system compare well with electromagnetic simulations and verify the novel sensor system concept. As predicted by the model, the prototype system solves the two main issues in antenna-based RFID sensor systems experienced so far, i.e., the impairment of system performance by modulating the sensor state information on the tag signal and the need for recurring system calibration due to changes in reader–tag distance.

RFID 3-D Indoor Localization for Tag and Tag-Free Target Based on Interference

Passive indoor localization has gained much attention recently. Numerous applications including storage management and somatosensory systems would benefit from accurate passive indoor localization. As a potential technology for the internet of things, radio frequency identification (RFID) has many advantages for indoor localization, such as low cost, parallel processing, and low complexity. In this paper, a passive indoor localization system, named Lobain, was proposed based on interference of ultrahigh frequency RFID tags. Using commercial off-the-shelf reader, antenna, and tags, this system, functions for tagged and tag-free item localization in 2-D and 3-D indoor environments. Small numbers of reference tags were used as sensors to improve performance and reduce cost. Unlike traditional methods, an improved propagation model and an innovative method were presented to extract a target’s channel information from a complicated received signal. A relative phase wrapping integer method was presented to solve the phase wrapping problem of reference tags, and the least-squares method was used to optimize the tradeoff between number of reference tags and accuracy. A tag and tag-free items including shrimp chips, cola, and instant noodles were localized as single target in the evaluation experiments. The prototype achieved mean 2-D median localization errors of 5.9 (x-axis) and 8.2 cm (y-axis), and achieved mean 3-D median errors of 9 (x-axis), 6.7 (y-axis), and 13.3 cm (z-axis).

Time-Reversal Processing for Downlink-Limited Passive UHF RFID in Pulsed Wave Mode

This letter provides experimental evidence that, in a complex environment, a time-reversal processing of electromagnetic waves can increase the energy efficiency of the reader to tag communication and, hence, can increase the activation range of a passive ultrahigh frequency (UHF) radio frequency identification (RFID) system. A first experiment performed in a free-space environment shows that in addition to the classical continuous wave (CW) mode, a type AD222 passive UHF RFID tag can successfully operate in a pulsed wave (PW) mode using pulses with half-width 5 ns and period 35 ns. In a second experiment performed in a complex multipath environment, it is shown that the energy efficiency of the RFID system in the PW mode can be increased by applying a time-reversal (TR) processing strategy. Furthermore, it is shown that both PW and TR strategies involve less energy to activate the tag than the classical CW mode does. As a consequence, given a fixed amount of energy, TR processing can increase the activation range of the RFID system.

Glove-Integrated Passive UHF RFID Tags—Fabrication, Testing and Applications

Passive radio-frequency identification (RFID) technology enables versatile energy- and cost-efficient wireless platforms. We present passive ultra-high frequency (UHF) RFID tags integrated into normal work gloves for wearable RFID applications. The tags were designed to be functional throughout the global UHF RFID frequency range. The use environments of work gloves are challenging, for example due to moisture and mechanical stresses, which means the glove-integrated solutions have unique reliability issues to consider. We introduce 3-D printing of a flexible thermoplastic material directly onto the glove and embed electro-textile antennas and RFID microchip components inside the 3-D-printed structure. This manufacturing method solves the above-mentioned reliability challenges and enables the practical use of glove-integrated passive RFID tags. The performance of the fabricated glove-tags is first evaluated on a male test subject in an EMC room and in an office environment. Based on the wireless measurement results, the read ranges of the glove-tags are around 2–3 m throughout the frequency range of 800–1000 MHz. These results meet the requirements of many practical applications of glove-tags. Further, these glove-tags are found to endure extreme moisture and mechanical stresses, which supports their use in versatile use environments. Finally, the developed glove-tags are successfully tested in actual use situations for identification and access control. These results are very promising, especially considering the cost-effectiveness and the easiness of tag integration into different types of gloves.

Fixed UHF RFID Reader Antenna Design for Practical Applications: A Guide for Antenna Engineers With Examples

An overview of Ultra High Frequency (UHF) Radio-Frequency Identification (RFID) practical applications and the reader antenna design requirements are presented in this paper. As each application is different and their physical, environmental, electrical, and Radio-Frequency (RF) requirements will also differ, a design methodology is proposed by analyzing all the requirements for a practical reader antenna. Reader antenna performance measures and test procedures are also formulated. As an example, an embeddable reader antenna is designed and fabricated for self-billing kiosk application in a retail environment. The designed antenna is measured in terms of various RF and RFID performance metrics and validated that it meets all the requirements sought by the application.

Design of new power generating circuit for passive UHF RFID tag

In this paper, we propose a new power generating circuit for passive ultra high frequency (UHF) RFID tag. The proposed power generating circuit consists of a RF limiter, a high power efficiency and high sensitivity full wave radio frequency (RF) wave rectifier and a low-power regulator with NMOS diodes work like a DC-limiter. The design method proposed in this study use one low drop out (LDO) regulator to provide tow output stable supply voltages vdd1 of value 1V for the digital section supply, and vdd2 of value 0.5V for the analog front-end section power supply. The proposed power generating circuit is optimized in terms of power consumption of RFID tag system to have a high operating range under conditions of 50 Ohm antenna, -24 dBm input RF power, 900MHz and 1 M DC, with low power dissipation and 29.15% large power conversion efficiency. The power generating circuit was designed, simulated and layouted in Cadence using TSMC 180 nm technology. The final design occupies approximately 0.25mm<sup>2</sup>.

Multipolarized Reader Antenna With Periodic Units Based on Electric Field Coupling for UHF RFID Near-Field Applications

This paper presents a multipolarized reader antenna with periodic units based on electric field coupling for near-field applications of ultra-high frequency (UHF) radio frequency identification (RFID). The antenna units are composed of two branches that are mirror-symmetric with respect to the ${x}$ -axis and produce ±45° linear polarization. A 90° phase difference is produced between the upper and lower branches by introducing a phase shifter into the upper branch, so that the near-field electric fields excited in the horizontal plane exhibit a quasi-circular polarization distribution. The proposed design is validated by simulations and experiments using prototype 4-unit and 6-unit antennas. The proposed antennas can generate strong and uniform electric fields and provide reading volumes of 400 mm $\times \,\,320$ mm $\times \,\,300$ mm and 560 mm $\times \,\,320$ mm $\times \,\,300$ mm for the 4-unit and 6-unit antennas, respectively, regardless of the orientation of the tags in the horizontal plane. In addition, the far-field gain is low with a maximum of −6 dBi, thus the misreading of tags outside the reading region is avoided. The proposed antenna achieves impedance matching over the Chinese UHF RFID band (920–925 MHz) and therefore meets the application requirements of near-field RFID reader antennas.

A Multitag Cooperative Localization Algorithm Based on Weighted Multidimensional Scaling for Passive UHF RFID

Radio frequency identification (RFID) technology, which is one of the important implementation ways of Internet-of-Things (IoT), has achieved much attention in indoor localization areas. Passive ultrahigh frequency (UHF) RFID tag localization has a great development recently. Most of traditional passive UHF RFID localization algorithms can only achieve the position of one tag at a time while multitag localization is desired in many RFID applications. In this paper, we proposed the weighted multidimensional scaling (WMDS) based on received signal strength (RSS) method and the tag-to-tag communication system to achieve multitag cooperative localization. The targets are marked with passive UHF RFID tags. RSS method is used to determine the distance between readers and target tags through channel models. We can also obtain the estimated distances between target tags by the tag-to-tag communication system. The estimated locations of the tags are determined by the calculation of Euclidean distance matrix through a few iterations. Simulation results show that the WMDS algorithm achieves higher localization accuracy than traditional algorithms and the cooperation between tags improves the localization accuracy.

Carrier extraction cancellation circuit in RFID reader for improving the Tx‐to‐Rx isolation

A novel high-isolation leakage carrier cancellation system, which is highly required in the ultra-high frequency (UHF) radio frequency identification (RFID) reader circuit, is presented here. First, a novel deformed microstrip rat-race circuit (RRC) is designed to take the place of traditional circulator. The microstrip device is integrated in the leakage carrier extraction circuit, which is connected in the receiver and balanced by the open-loop circuit. One of the advantages of the delicately designed system is that no need of real-time tracking to balance the variations of the amplitude and the phase of the leakage carrier. Results demonstrate that the leakage carrier with the leakage carrier extraction cancellation circuit (CECC) is improved to be 108 dB in UHF RFID narrow bands from 920 to 925 MHz and to be 117 dB at the centre frequency point. The Tx-to-Rx isolation is improved to be 48–70 dB higher than that of other cancellation circuits. The proposed leakage carrier cancellation system shows obvious improvement on the efficiency of the isolation. Both the experiment and simulation demonstrate the merits of properties of the novel designed system with the benefits of improved isolation and lower cost.

Continuously tracking of moving object by a combination of ultra-high frequency radio-frequency identification and laser range finder

Due to the unique and contactless way of identification, radio-frequency identification is becoming an emerging technology for objects tracking. As radio-frequency identification does not provide any distance or bearing information, positioning using radio-frequency identification sensor itself is challenging. Two-dimensional laser range finders can provide the distance to the objects but require complicated recognition algorithms to acquire the identity of object. This article proposes an innovative method to track the locations of dynamic objects by combining radio-frequency identification and laser ranging information. We first segment the laser ranging data into clusters using density-based spatial clustering of applications with noise (DBSCAN). Velocity matching–based approach is used to track the location of object when the object is in the radio-frequency identification reading range. Since the radio-frequency identification reading range is smaller than a two-dimensional laser range finder, velocity matching–based approach fails to track location of the object when the radio-frequency identification reading is not available. In this case, our approach uses the clustering results from density-based spatial clustering of applications with noise to continuously track the moving object. Finally, we verified our approach on a Scitos robot in an indoor environment, and our results show that the proposed approach reaches a positioning accuracy of 0.43 m, which is an improvement of 67.6% and 84.1% as compared to laser-based and velocity matching–based approaches, respectively.

Gain Enhancement of a Looped Slots Patch Antenna for Passive UHF RFID Tags Applications in Metallic Supports

The objects with high conductivity such as metals consist of a challenge for passive RFID (Radio Frequency IDentification) tags in UHF (Ultra High Frequency) due to their effects on tags antennas performance. In this paper, a passive antenna for UHF RFID tags applications on metallic supports is presented. The antenna structure is constituted of a rectangular patch with looped slots printed on three-layer substrate and deposited on a regular ground plane. The looped slots are used to match the antenna impedance to the chip impedance in order to maximize power transfer. The three-layer substrate is adopted to improve the antenna gain, and the regular ground plane is added to act as fixed-size metallic plate. The antenna performance in free space and the one attached to the metallic surfaces are compared. The metallic plate size variation effects on antenna performance are studied by fixing the proposed antenna over different sizes of square copper plates which are multiple to the antenna size, and evaluated using the 3D electromagnetic simulator: HFSS (High Frequency Structure Simulator). The proposed antenna is designed to be used on high dimensions metallic objects such as the containers. It achieves a stable performance when the metallic surface size is five times larger than the antenna size: a read range of 16 m, an antenna gain about 2.5 dB and a bandwidth that covers all passive UHF-RFID band.

Radio-Frequency Identification Specimen Tracking to Improve Quality in Anatomic Pathology

Preanalytic errors, including specimen labeling errors and specimen loss, occur frequently during specimen collection, transit, and accessioning. Radio-frequency identification tags can decrease specimen identification and tracking errors through continuous and automated tracking of specimens. To implement a specimen tracking infrastructure to reduce preanalytic errors (specimen mislabeling or loss) between specimen collection and laboratory accessioning. Specific goals were to decrease preanalytic errors by at least 70% and to simultaneously decrease employee effort dedicated to resolving preanalytic errors or investigating lost specimens. A radio-frequency identification specimen-tracking system was developed. Major features included integral radio-frequency identification labels (radio-frequency identification tags and traditional bar codes in a single printed label) printed by point-of-care printers in collection suites; dispersed radio-frequency identification readers at major transit points; and systems integration of the electronic health record, laboratory information system, and radio-frequency identification tracking system to allow for computerized physician order entry driven label generation, specimen transit time tracking, interval-based alarms, and automated accessioning. In the 6-month postimplementation period, 6 mislabeling events occurred in collection areas using the radio-frequency identification system, compared with 24 events in the 6-month preimplementation period (75% decrease; P = .001). In addition, the system led to the timely recovery of 3 lost specimens. Labeling expenses were decreased substantially in the transition from high-frequency to ultrahigh frequency radio-frequency identification tags. Radio-frequency identification specimen tracking prevented several potential specimen-loss events, decreased specimen recovery time, and decreased specimen labeling errors. Increases in labeling/tracking expenses for the system were more than offset by time savings and loss avoidance through error mitigation.

UHF meander bowtie antenna for RFID application

This paper describes the development of four different ultra-high frequency (UHF) radio frequency identification (RFID) tag antenna using polycarbonate material or transparent paper as the substrate and aluminum tape as the radiating element. The main advantage of the method is that the materials are easy to obtain where it can be found in any hardware stores or in any general online shop. Plus, the antennas are designed in such a way that a meander line is traced along the shape of a bowtie antenna so that the antenna would operate at UHF band. The results of all four of the tag antenna designs are discussed and compared using graph obtained from Computer Simulation Technology (CST) simulation results and measurement results obtained from a portable Vector Network Analyzer (VNA) for the reflection coefficient, S 11 , and measurement results taken from VNA in chamber room for the radiation pattern. Finally, the results show that the measured results are in agreement with the simulated result and that the UHF RFID tag antennas are able to operate at UHF RFID band.

UHF meander bowtie antenna for RFID application

This paper describes the development of four different ultra-high frequency (UHF) radio frequency identification (RFID) tag antenna using polycarbonate material or transparent paper as the substrate and aluminum tape as the radiating element. The main advantage of the method is that the materials are easy to obtain where it can be found in any hardware stores or in any general online shop. Plus, the antennas are designed in such a way that a meander line is traced along the shape of a bowtie antenna so that the antenna would operate at UHF band. The results of all four of the tag antenna designs are discussed and compared using graph obtained from Computer Simulation Technology (CST) simulation results and measurement results obtained from a portable Vector Network Analyzer (VNA) for the reflection coefficient, S 11 , and measurement results taken from VNA in chamber room for the radiation pattern. Finally, the results show that the measured results are in agreement with the simulated result and that the UHF RFID tag antennas are able to operate at UHF RFID band.

Compact Crossed Dipole Antenna With Meandered Series Power Divider for UHF RFID Tag and Handheld Reader Devices

A low-profile and meandered crossed dipole antenna design for ultrahigh-frequency (UHF) radio-frequency identification (RFID) circularly polarized (CP) tag or handheld reader application is described in this communication. The crossed dipole CP condition is obtained by employing a series power divider meandered at the center of the dielectric substrate, and a surrounding ring which acts as a T-match network guarantees impedance matching. The series power divider alleviates the problem of using a balun when the crossed dipole is fed with a 50 $\Omega $ coaxial cable. A prototype has been manufactured on a $56\times 56\times0.4\,\,\text {mm}^{3}$ FR4 dielectric substrate, and the measurement results show a $S_{11}\le -10$ dB bandwidth of more than 14.4% (865.6–1000 MHz), an axial ratio (AR) ≤ 3 dB bandwidth of 2.8% (906–932 MHz) which can essentially cover the Federal communications commission (FCC) UHF RFID band, and a broadside RHCP peak gain of 1.4 dBic at 919 MHz. When the antenna is connected to an RFID tag chip, excellent read range performance within the whole 902–928 MHz bandwidth has been demonstrated (with maximum values of 7 and 9.9 m when interrogated with a linearly polarized and a CP reader antenna, respectively).

RF-Powered-Tag Intermodulation Uplink With Three-Tone Transmitter for Enhanced Uplink Power

An intermodulation RF-powered-tag uplink (UL) that exploits the rectifier third-order intermodulation (IM3) has been recently proposed. The key features for the IM3 ULs to outperform the conventional backscattering ULs are the frequency-division duplexing downlink/UL operation and the passive reuse. While the previously reported IM3 UL systems only transmit two-tone waveforms, this paper demonstrates that under a given transmitter (Tx) peak power and a given Tx average power, transmitting an optimized three-carrier Tx waveform can improve the IM3 UL power and the receiver signal-to-noise ratio without compromising the rectifier harvested dc power. The developed theory is based on power series analysis and is verified by nonlinear simulation and experimental results, which include two RF-powered reader-tag systems: The first one employs a custom designed ultra-high frequency (UHF) PCB rectenna and the second one uses a commercial Gen-2 UHF radio-frequency identification inlay.

Inkjet‐printed UHF RFID tag based system for salinity and sugar detection

AbstractThis article presents an RFID system to detect the salinity and sugar contents of water. The proposed system is based on low‐cost ink‐jet printed passive ultrahigh frequency (UHF) RFID tag. The tag is designed using slot match technique, which poses a good imaginary impedance match with RFID chip both in free space and after mounting on the water bottle. Moreover, the tag antenna is exploited as a sensor to detect salt and sugar contents of water by measuring the backscatter power from the tag in term of received signal strength indicator (RSSI). A Tagformance Pro setup form Voyantic is used for measuring RSSI. Furthermore, an approximate relationship is derived between backscatter power and no. of grams of salt and sugar dissolved in water. This study paves a way to check the contents of drinks using portable devices, which is pivotal for healthcare applications in smart cities and the future Internet of things (IoT).