Radio Frequency Identiflcation Research Articles

RFID Indoor Positioning Method Based on Virtual Reference Tags and Bayesian Estimation

At present, more and more applications require the indoor positioning information of objects, making the indoor positioning technology become one of the hotspots. In this paper, LANDMARC algorithm and VIRE algorithm are analysed, which allow the technology of Radio Frequency Identiflcation (RFID) to be applied in indoor positioning. On this basis, the improvement is made and RFID indoor positioning method based on virtual reference tags and Bayesian estimation is proposed. Experimental results indicate that the improved algorithm has further improved than LANDMARC algorithm and VIRE algorithm in terms of positioning accuracy.

RECONFIGURABLE ANTENNA FOR RFID READER AND NOTCHED UWB APPLICATIONS USING DTO ALGORITHM

In this article, the approach involving Dynamic Threshold Optimization (DTO) algorithm is considered to optimize a new compact reconflgurable antenna to be applied to triple band Radio Frequency Identiflcation (RFID) and to ultra wideband (UWB) antenna with multiple bands notched. The antenna is implemented by using the existing techniques, such as loading an L-type band-stop fllter, inserting a split ring resonator (SRR) as well as connecting L branches to the radiation disk proposed by us. In case of RFID applications, triple-band RFID 915/2450/5800MHz are achieved separately. The results prove that this kind of antenna can be applied in RFID reader to avoid interference with other wireless systems. RF MEMS switches are used to reconflgure the antenna to be suitable for the application in the notched UWB communication systems. The DTO algorithm program is implemented using MATLAB-software and linked to the CST Microwave studio software to simulate the antenna. In addition, the optimized antenna is assessed using the Finite Difierence Time Domain (FDTD) program written with MATLAB to validate the results. The experimental results for the RFID and UWB antennas show good agreement with simulated ones. The radiation patterns are satisfactorily omnidirectional across the antenna's operation bands.

A BROADBAND CPW-FED CIRCULARLY POLARIZED SQUARE SLOT ANTENNA FOR UHF RFID APPLICATIONS

A broadband CPW-fed circularly polarized square slot antenna for ultra-high-frequency (UHF) radio frequency identiflcation (RFID) applications is proposed. It consists of a square slot embedded with a spur line along diagonal and an F-shaped feeding structure. The proposed antenna achieves an impedance bandwidth about 307MHz (34.6% @886MHz) and a 3dB axial ratio (AR) bandwidth about 232MHz (24.3% @954MHz). The 3dB AR beam-width is about 96 degrees over the UHF band of 840{960MHz. The proposed reader antenna based on CPW structure is easy to integrate. With the symmetry and bidirectional radiation pattern, there are less readers needed in some applications, such as access control, than the reader with unidirectional pattern, which will deflnitely decrease the implemented cost. Therefore, this universal design with desired performance across the entire UHF RFID band (from 840MHz to 960MHz) can be applied to all the UHF RFID applications worldwide. Detailed considerations of the design and main parameters will be studied in this paper.

A NOVEL DESIGN OF COMPACT DIPOLE ANTENNA FOR 900 MHZ AND 2.4 GHZ RFID TAG APPLICATIONS

A novel design of fractal dipole antenna has been presented for RFID (Radio Frequency Identiflcation) tag applications, which is based on the fractal theory. The antenna consists of two third iteration triangle fractal arms, and has been designed to work at 900MHz (GSM) and 2.4GHz (ISM), and its size is 89mm£29mm£1:6mm. The simulated results for various characteristics of the antenna have been shown using flnite element technique based commercial software ANSOFT HFSS. The simulated and measured impedance results are in good agreement.

COMPACT LOOP ANTENNA FOR NEAR-FIELD AND FAR-FIELD UHF RFID APPLICATIONS

A novel type of radio frequency identiflcation (RFID) reader antenna is proposed for mobile ultra-high frequency (UHF) RFID device. By folded-dipole loop structure with parasitic element, a small antenna size of 31⁄31⁄1:6mm 3 is achieved. The antenna with difierent parasitic element size can work on difierent UHF RFID bands. The antenna prototype is fabricated and the measured bandwidth is around 13.5MHz (915.5{929MHz), which covers the China RFID Band (920{925MHz). The measured reading distance achieves 65mm with the near-fleld RFID tag and 1.17m with the far-fleld tag. The measurement agrees well with simulated result and shows that antenna is desirable for both near-fleld and far-fleld UHF RFID applications.

A MINIMIZED WIDEBAND ANTENNA ARRAY WITH DECOUPLING NETWORKS FOR UHF RFID APPLICATIONS

A minimized wideband antenna array is presented for ultra-high frequency (UHF) radio frequency identiflcation (RFID) reader applications. The antenna array consists of two E-shaped patch antennas and a feeding network, with the overall size 200 £ 100 £ 20mm 3 . The feeding network could efiectively decrease the antenna mutual coupling and improve the bandwidth. The measured bandwidth is about 68MHz (896{964MHz) under the condition of voltage standing wave ratio (VSWR) less than 2, which covers various RFID bands including North American (902{928MHz), Chinese (920{ 925MHz) and Japanese (952{955MHz). The average gain is 4.5dBi in UHF band. The principles of the antenna and the feeding network are also discussed and analyzed in this paper. At last, the key parameters are studied and show the antenna robustness.

A CIRCULARLY POLARIZED COMPACT ANTENNA FOR UHF BAND RFID READER

This paper presents a circularly polarized compact antenna based on the concept of Yagi-Uda antenna. By properly arranging three ring resonators operating at the fundamental mode, a compact Yagi-Uda like antenna is proposed to form directional pattern. This proposed antenna has comparable size with the ring resonator of quarter-wavelength, while the performances are comparable with the conventional microstrip antenna of half-wavelength. To validate the proposed design methodology, an antenna working at UHF radio- frequency identiflcation (RFID) band is benchmarked. Both simulated and measured results are shown for comparison.

A NOVEL CIRCULAR POLARIZATION RFID READER ANTENNA WITH A MULTI-BENDING FEEDING STRIP FOR HANDHELD APPLICATIONS

This paper proposes a novel corner-fed Circular Polariza- tion (CP) reader antenna for handheld Ultra-High Frequency (UHF) Radio Frequency Identiflcation (RFID) application. The CP mecha- nism is accomplished by a multi-bending feeding strip located at corner of a high dielectric constant (K = 60) ceramic substrate. By using the high dielectric substrate, the dimension of the proposed antenna can be efiectively reduced to 27 £ 27 £ 4mm 3 , which consists of a top radiat- ing patch, an antenna ground plane, a coupling multi-bending feeding strip, and a SMA connector for RF input. The top radiating patch is printed on the top surface of the ceramic substrate and the antenna ground plane is formed on the opposite side. The central frequency of resonant band can be easily controlled by adjusting the size of the top radiating patch. By optimizing the coupling feeding mechanism, not only impedance matching can be achieved for bandwidth operation in Taiwan's UHF RFID band, but also two orthogonal fleld components

DESIGN OF DUAL CIRCULARLY POLARIZED ANTENNA WITH HIGH ISOLATION FOR RFID APPLICATION

In this paper, a dual-fed circularly polarized antenna design with high isolation is presented for radio frequency identiflcation (RFID) reader. The proposed antenna is excited by two fed ports connected with a circular split-ring microstrip line underneath the ground plane. A radial aperture in the ground plane provides coupling between the split-ring microstrip and radiating patch. For multiple RFID band requirements, the dimension of the aperture can be modifled to obtain high isolation on difierent RFID Band. Finally, an antenna prototype for China RFID Band (920{925MHz) is fabricated. The measured results agree well with simulation, and show 10-dB matching bandwidth of 18% (820{1000MHz), 3-dB axial ratio (AR) bandwidth of 11% (854{960MHz), and 25-dB isolation bandwidth of 11MHz (917{928MHz).

A LONG-RANGE COMPUTATIONAL RFID TAG FOR TEMPERATURE AND ACCELERATION SENSING APPLICATIONS

In this paper, the design, realization, and experimental validation of a battery-assisted radio frequency identiflcation (RFID) tag featuring sensing and computation capabilities are presented. The sensor-augmented RFID tag comprises an ultra-low-power microcontroller, temperature sensor, 3-axis accelerometer, non-volatile storage, and a new-generation I 2 C-RFID chip for communication with standard UHF EPCglobal Class-1 Generation-2 readers. A preliminary printed-circuit-board prototype, connected to a 3-V/225-mAh lithium battery, provides a lifetime up to approximately 3 years when sensing and RFID-based communication tasks are performed every 10 seconds. Moreover, the device exhibits indoor transmission ranges up to 22m, 6m, and 5m when attached to foam, concrete, and wood respectively. The encouraging results achieved for an emulated application scenario demonstrate the suitability of the device to be adopted in contexts where temperature and acceleration sensing are required.

A SLIM WIDEBAND AND CONFORMAL UHF RFID TAG ANTENNA BASED ON U-SHAPED SLOTS FOR METALLIC OBJECTS

A slim wideband patch antenna designed for the ultra- high frequency (UHF) band radio frequency identiflcation (RFID) tag is presented in this paper, which can be mounted on ∞at or curved metallic surfaces directly. The presented antenna is fabricated on a very thin (only 0.5mm) and low-cost PET substrate (r = 3:8, tan- = 0:02). The proposed design consists of tow coplanar patches radiation unities which are electrically connected to the metallic ground through two symmetrical shorting walls placed at both edge sides of the patches. Double symmetrical U-shaped slots are etched out to improve the antenna bandwidth. A perfect matching between antenna and tag chip can be easily obtained by varying the geometry parameters of the slots. The simulated bandwidth is about 97MHz, which covers the Europe and North America UHF RFID frequency range. The measured maximum reading range of the proposed antenna can be up to 5m when the tag is mounted on a metal plate whose size is 150 £ 150 £ 8mm 3 .

WI-FI ENERGY HARVESTER FOR LOW POWER RFID APPLICATION

In recent years, active Radio Frequency Identiflcation (RFID) tags have crossed into ultra low power domain. With obvious advantages over passive tags, a setback for active tag growth is the need for battery replacement and limited operational life. Battery life could be extended by scavenging surrounding Wi-Fi signals using rectenna architecture which consists of a receiving antenna attached to a rectifying circuit. A seven stage Cockroft-Walton voltage multiplier optimized for low input power (below 0dBm) is proposed. Prototype was fabricated on RT/Duroid 5880 (RO5880) printed circuit board (PCB) substrate with dielectric constant and loss tangent of 2.2 and 0.0009 respectively. Experimental results show that 2V output voltage can be harvested from an operating frequency of 2.48GHz with i9dBm (0.13mW) sensitivity with 1.57mm board thickness.

A NOVEL TECHNIQUE FOR BROADBAND CIRCULAR POLARIZED PIFA AND DIVERSITY PIFA SYSTEMS

In this paper, a novel technique for planar inverted-F antenna (PIFA) with broadband circular polarization and pattern diversity is proposed. A defeated ground structure (DGS) has achieved broadband circular polarized (CP) PIFA by using a square branch at the ground corner with arrow-shaped slot. The pattern diversity PIFA system consists of two CP PIFAs placed symmetrically on the diagonal of DGS. Furthermore, the DGS improves port-to-port isolation by using another smaller square branch at the opposite ground corner. Finally, a prototype is fabricated and measured. The measured results agree well with simulation, and show 10-dB matching bandwidth of 16.3% (825{986MHz), 3-dB axial ratio (AR) bandwidth of 15.5% (830{982MHz), and 25-dB isolation bandwidth of 12.4% (848{968MHz), which shows suitability for radio-frequency- identiflcation (RFID) application.

DETERMINATION OF DIELECTRIC PROPERTY OF CONSTRUCTION MATERIAL PRODUCTS USING A NOVEL RFID SENSOR

This paper presents a concept, by which radio frequency (RF) tags are employed as remotely read dielectric-property sensors to determine qualities of some construction material products (CMPs); e.g., light weight concrete (LWC), mortar specimens and concrete. Using the dependency of the read range of the passive RF identiflcation (RFID) sensor system on the electromagnetic properties of CMPs near or in contact with RFID tags, the qualities of CMPs can be determined through their estimated dielectric properties. Theoretical formulation is provided, and numerical simulations are performed for optimal design of passive RFID tag antennas suitable for RFID sensors and for read-range calculations. In addition, a series of measurements is performed to measure read ranges of the passive RFID sensor system for an LWC as an example of CMPs, and these measured read ranges will be processed appropriately to inversely determine the dielectric constant of the LWC under test, which in turn provides information on its qualities. It is found that the novel RFID sensor can be employed to determine the dielectric properties of the LWC under test with reasonable accuracy.

IMPLEMENTATION OF RFID AND BLUETOOTH TECHNOLOGY FOR DATA TAGGING AND TRANSMISSION TO POINT OF SALE

The design of wireless technology which involves radio frequency identiflcation (RFID) and Bluetooth technology for tagging and transmission of data that will be applied to point of sale (POS) is presented. A complete POS circuitry system has been designed to allow certain item to be a tag easily identifled and localized. This is implemented by using RFID technology which will communicate with personal computer (PC) either through Ethernet or Wifl connection. An Impinj RFID reader and Bluetooth mobile phone are selected in the proposed POS system. Matlab simulation has been performed for RFID transceiver part and Bluetooth data transmission. A prototype software is developed to interface the Impinj RFID reader through the Ethernet connection. Additionally, a data encryption from Bluetooth is paired with PC to achieve a secure and simple pairing feature when customer transaction is performed. It involves hardware and software implementation. Moreover, in simulation result, a double side band modulation is used to design the RFID reader for better item tagging. The results show the feasibility of using this design for POS and achieving very good read ranges. Finally, Bluetooth system enables fast transaction and makes purchase securely by using the proposed asymmetric algorithm.

A SRR-BASED NEAR FIELD RFID ANTENNA

In this paper, a compact near fleld reader antenna is proposed for ultra-high frequency (UHF) radio frequency identiflcation (RFID) applications. The antenna structure is composed of two split-ring-resonators (SRRs) and miniaturized to a special small size of 21 ⁄ 21 ⁄ 1:6mm 3 for mobile RFID application. The measured bandwidth of antenna prototype is 13MHz (914.5{927.5MHz) with re∞ection coe-cient less than i10dB, which covers the China RFID band II (920{925MHz). Simulation shows that the proposed antenna achieves a strong and uniform magnetic fleld distribution in the near fleld region, and the reading range is up to 42mm with near fleld RFID tag. Through modifying the parameters of SRRs, the antenna can operate on difierent UHF RFID bands (Europe band, China band I&II etc.).

MONOPOLE-BASED RECTENNA FOR MICROWAVE ENERGY HARVESTING OF UHF RFID SYSTEMS

This paper presents a rectifying antenna (rectenna) for the harvesting of the microwave energy associated to UHF (Ultra- High Frequency) Radio Frequency IDentiflcation (RFID) systems. The proposed device uses a capacitively loaded T-shaped monopole with a coplanar waveguide feeding line as receiving antenna and a flve-stage voltage multiplier as rectifler. Experimental results demonstrating an RF-to-DC conversion e-ciency of about 54% with an input power density of 80W/cm 2 will be presented and discussed.

SWITCHABLE DISTANCE-BASED IMPEDANCE MATCHING NETWORKS FOR A TUNABLE HF SYSTEM

Distance-based impedance matching networks for a tunable high frequency (HF) system are presented in this paper for the improved performance. The transmitting antenna for a HF system with an operating frequency of 13.56MHz consists of a two-turn loop and three channel impedance matching networks corresponding to the distance of the receiving antenna. Each impedance matching network maximizes the system performance such as uniform power e-ciency and reading range at speciflc distance between a transmitting and a receiving antenna. By controlling the distance-based matching networks, the power e-ciency of the proposed antenna improves by up to 89% compared to the conventional antenna system with the flxed matching (FM) condition for distances, and the reliable reading range according to the impedance matching conditions is also increased. The proposed technique is applicable for near fleld communication (NFC), radio frequency identiflcation (RFID), or wireless power transfer (WPT) devices.

COMPACT METAL MOUNTABLE UHF RFID TAG ON A BARIUM TITANATE BASED SUBSTRATE

The development of a compact metal mountable Radio- Frequency IDentiflcation (RFID) tag antenna on a ceramic substrate based on Barium Titanate is presented. The performance limitations and design trade-ofis of metal mountable RFID tag antennas are reviewed and the favorable features of a high-permittivity antenna substrate for the development of antennas for metal mountable RFID tags are discussed. The simulation-based tag antenna design process is outlined and the measured read range of the developed metal mountable tag on conductive platforms of various sizes is presented.

A NOVEL WIDEBAND CIRCULARLY POLARIZED ANTENNA FOR WORLDWIDE UHF BAND RFID READER APPLICATIONS

This paper presents the novel design of a wideband circularly polarized (CP) Radio Frequency Identiflcation (RFID) reader microstrip patch antenna for worldwide Ultra High Frequency (UHF) band which covers 840{960MHz. The proposed antenna, which consists of a microstrip patch with truncated corners and a cross slot, is placed on a foam substrate (r = 1:06) above a ground plane and is fed through vias through ground plane holes that extend from the quadrature 3dB branch line hybrid coupler placed below the ground plane. This helps to separate feed network radiation, from the patch antenna and keeping the CP purity. The prototype antenna was fabricated with a total size of 225 £ 250 £ 12:8mm 3 which shows a measured impedance matching band of 840{1150MHz (31.2%) as well as measured rotating linear based circularly polarized radiation patterns. The simulated and measured 3dB Axial Ratio (AR) bandwidth is better than 23% from 840{1050MHz meeting and exceeding the target worldwide RFID UHF band.