2,536 research outputs found
Target Read Operation of Passive Ultra High Frequency RFID Tag in a Multiple Tags Environment
Passive ultra-high frequency (UHF) radio frequency Identification (RFID) has emerged as a promising solution for many industrial applications. Passive UHF systems are relatively inexpensive to implement and monitor, as no line of sight is required for the communication. There are several advantages to using a passive RFID system. For example, no internal power source is required to activate the tags, and lower labor costs and efficient multitasking operations are expected in a long term scenario. However, due to factors such as tag-to-tag interference and inaccurate localization, RFID tags that are closely spaced together are difficult to detect and program accurately with unique identifiers. This thesis investigates two main ways to enable and improve multi-tag operations: physical tag placement and design of the near-field RFID reader antenna. First, several factors that affect the ability to encode a specific tag with unique information in the presence of other tags are investigated, such as reader power level, tag-to-antenna distance, tag-to-tag distance and tag orientation. A Full Factorial Design is carried out to study the effects of each of the factors and factor interactions. Results suggest a preliminary minimum tag-to-tag spacing which enables the maximum number of tagged items to be uniquely encoded without interference. In order to individually read each tag in a multi-tag form, an experimental device is built to enable controlled movement and positioning of the readerâs antenna to the location of each of the tags. The experimental device is also designed to test other mechanical means of isolating the tags, such as shielding and mechanical isolation of the tagged media. Furthermore, to test a second method of improving the efficacy of programming tags uniquely in a multi-tag environment, the readerâs antenna is redesigned to confine the electromagnetic field distribution to reduce the probability of activating non-targeted tags in the surrounding. Using the commercial software package ANSYS High Frequency Structural Solver (HFSS), the coupling interaction between the readerâs antenna and RFID tags was simulated to investigate the relative voltage induced in the target tag relative to each of the proximal tags. The new antenna is then fabricated and validated with the simulation results. With a better antenna design and ideals tag placement, the read operation of multiple tags can be improved and made more reliable. These findings can potentially expedite the process of field programming in item-level tagging and increase the throughput rate of unique tag encoding
Design of a Wideband Inductively Coupled Loop Feed Patch Antenna for UHF RFID Tag
A planar wideband patch antenna for ultra-high frequency (UHF) radio frequency identification (RFID) tag for metallic applications is presented in this research work. Three different shape patches are inductively coupled to a triangle loop to form wide impedance bandwidth for universal application UHF (860-960 MHz) RFID. The structure of proposed antenna exhibits planar profile to provide ease of fabrication for cost reduction well suited for mass production. The simulation of the antenna was carried out using Finite Element Method (FEM) based software, Ansoft HFSS v13. The simulated and measured impedance bandwidth of 113 MHz and 117 MHz (Return Lossâ„6 dB) were achieved to cover the entire UHF RFID operating frequency band worldwide. The simulated and measured radiation patterns at the operating frequency of 915 MHz are in good agreement. Moreover the simulated minimum antenna gain at the bore sight direction in free space and when mounted on 200 x 200 mm2 metal plate are -15 dBi and -14dBi respectively which is enough to provide reasonable read range over the entire UHF RFID system operating band
A Broadband UHF Tag Antenna For Near-Field and Far-Field RFID Communications
The paper deals with the design of passive broadband tag antenna for Ultra-High Frequency (UHF) band. The antenna is intended for both near and far fields Radio Frequency Identification (RFID) applications. The meander dipole tag antenna geometry modification is designed for frequency bandwidth increasing. The measured bandwidth of the proposed broadband Tag antenna is more than 140 MHz (820â960 MHz), which can cover the entire UHF RFID band. A comparison between chip impedance of datasheet and the measured chip impedance has been used in our simulations. The proposed progressive meandered antenna structure, with an overall size of 77 mm Ă 14 mm Ă 0.787 mm, produces strong and uniform magnetic field distribution in the near-ïŹeld zone. The antenna impedance is matched to common UHF chips in market simply by tuning its capacitive and inductive values since a perfect matching is required in the antenna design in order to enhance the near and the far field communications. Measurements confirm that the designed antenna exhibits good performance of Tag identiïŹcation for both near-ïŹeld and far-ïŹeld UHF RFID applications
Spatial Identification Methods and Systems for RFID Tags
DisertaÄnĂ prĂĄce je zamÄĆena na metody a systĂ©my pro mÄĆenĂ vzdĂĄlenosti a lokalizaci RFID tagĆŻ pracujĂcĂch v pĂĄsmu UHF. Ăvod je vÄnovĂĄn popisu souÄasnĂ©ho stavu vÄdeckĂ©ho poznĂĄnĂ v oblasti RFID prostorovĂ© identifikace a struÄnĂ©mu shrnutĂ problematiky modelovĂĄnĂ a nĂĄvrhu prototypĆŻ tÄchto systĂ©mĆŻ. Po specifikaci cĂlĆŻ disertace pokraÄuje prĂĄce popisem teorie modelovĂĄnĂ degenerovanĂ©ho kanĂĄlu pro RFID komunikaci. DetailnÄ jsou rozebrĂĄny metody mÄĆenĂ vzdĂĄlenosti a odhadu smÄru pĆĂchodu signĂĄlu zaloĆŸenĂ© na zpracovĂĄnĂ fĂĄzovĂ© informace. Pro ĂșÄely lokalizace je navrĆŸeno nÄkolik scĂ©nĂĄĆĆŻ rozmĂstÄnĂ antĂ©n. Modely degenerovanĂ©ho kanĂĄlu jsou simulovĂĄny v systĂ©mu MATLAB. VĂœznamnĂĄ ÄĂĄst tĂ©to prĂĄce je vÄnovĂĄna konceptu softwarovÄ definovanĂ©ho rĂĄdia (SDR) a specifikĆŻm jeho adaptace na UHF RFID, kterĂĄ vyuĆŸitĂ bÄĆŸnĂœch SDR systĂ©mĆŻ znaÄnÄ omezujĂ. DiskutovĂĄna je zejmĂ©na problematika prĆŻniku nosnĂ© vysĂlaÄe do pĆijĂmacĂ cesty a poĆŸadavky na signĂĄl lokĂĄlnĂho oscilĂĄtoru pouĆŸĂvanĂœ pro smÄĆĄovĂĄnĂ. PrezentovĂĄny jsou tĆi vyvinutĂ© prototypy: experimentĂĄlnĂ dotazovaÄ EXIN-1, mÄĆicĂ systĂ©m zaloĆŸenĂœ na platformÄ Ettus USRP a antĂ©nnĂ pĆepĂnacĂ matice pro emulaci SIMO systĂ©mu. ZĂĄvÄreÄnĂĄ ÄĂĄst je zamÄĆena na testovĂĄnĂ a zhodnocenĂ popisovanĂœch lokalizaÄnĂch technik, zaloĆŸenĂœch na mÄĆenĂ komplexnĂ pĆenosovĂ© funkce RFID kanĂĄlu. Popisuje ĂșzkopĂĄsmovĂ©/ĆĄirokopĂĄsmovĂ© mÄĆenĂ vzdĂĄlenosti a metody odhadu smÄru signĂĄlu. Oba navrĆŸenĂ© scĂ©nĂĄĆe rozmĂstÄnĂ antĂ©n jsou v zĂĄvÄru ovÄĆeny lokalizaÄnĂm mÄĆenĂm v reĂĄlnĂœch podmĂnkĂĄch.The doctoral thesis is focused on methods and systems for ranging and localization of RFID tags operating in the UHF band. It begins with a description of the state of the art in the field of RFID positioning with short extension to the area of modeling and prototyping of such systems. After a brief specification of dissertation objectives, the thesis overviews the theory of degenerate channel modeling for RFID communication. Details are given about phase-based ranging and direction of arrival finding methods. Several antenna placement scenarios are proposed for localization purposes. The degenerate channel models are simulated in MATLAB. A significant part of the thesis is devoted to software defined radio (SDR) concept and its adaptation for UHF RFID operation, as it has its specialties which make the usage of standard SDR test equipment very disputable. Transmit carrier leakage into receiver path and requirements on local oscillator signals for mixing are discussed. The development of three experimental prototypes is also presented there: experimental interrogator EXIN-1, measurement system based on Ettus USRP platform, and antenna switching matrix for an emulation of SIMO system. The final part is focused on testing and evaluation of described positioning techniques based on complex backscatter channel transfer function measurement. Both narrowband/wideband ranging and direction of arrival methods are validated. Finally, both proposed antenna placement scenarios are evaluated with real-world measurements.
Antenna Design for Semi-Passive UHF RFID Transponder with Energy Harvester
A novel microstrip antenna which is dedicated to UHF semi-passive RFID transponders with an energy harvester is presented in this paper. The antenna structure designed and simulated by using Mentor Graphics HyperLynx 3D EM software is described in details. The modeling and simulation results along with comparison with experimental data are analyzed and concluded. The main goal of the project is the need to eliminate a traditional battery form the transponder structure. The energy harvesting block, which is used instead, converts ambient energy (electromagnetic energy of typical radio communication system) into electrical power for internal circuitry. The additional function (gathering extra energy) of the transponder antenna causes the necessity to create new designs in this scope
Dual-Band RFID Tag Antenna Based on the Hilbert-Curve Fractal for HF and UHF Applications
A novel single-radiator card-type tag is proposed which is constructed using a series Hilbert-curve loop and matched stub for high frequency (HF)/ultra high frequency (UHF) dual-band radio frequency identification (RFID) positioning applications. This is achieved by merging the series Hilbert-curve for implementing the HF coil antenna, and square loop structure for implementing the UHF antenna to form a single RFID tag radiator. The RFID tag has directivity of 1.75 dBi at 25 MHz, 2.65 dBi at 785 MHz, 2.82 MHz at 835 MHz and 2.75 dBi at 925 MHz. The tag exhibits circular polarisation with -3 dB axial-ratio bandwidth of 14, 480, 605 and 455 MHz at 25, 785, 835 and 925 MHz, respectively. The radiation characteristics of the RFID tag is quasi-omnidirectional in its two orthogonal planes. Impedance matching circuits for the HF/UHF dual-band RFID tag are designed for optimal power transfer with the microchip. The resulting dual-band tag is highly compact in size and possesses good overall performance which makes it suitable for diverse applications
RFID coverage extension using microstrip-patch antenna array
In this paper, a UHF-band 2 x 2 microstrip phased-array antenna is designed and implemented to extend the coverage of an RFID reader system. The phased-array antenna has four microstrip-patch antennas, three Wilkinson power dividers, and a transmission-line phase shifter. These are printed on a dielectric substrate with a dielectric constant of 4.5. The array has dimensions of 34 cm x 45 cm, operating at a frequency of 867 MHz, as specified in RFID Gen2 protocol European standards. The phased-array antenna has a measured directivity of 12.1 dB, and the main-beam direction can be steered to angles of +/- 40 degrees, with a HPBW of 90 degrees. The phased-array antenna is used as the receiving antenna in a commercial reader system. Experimental results indicate that the coverage of the RFID system with the phased-array antenna is superior to the coverage with a conventional broader-beamwidth microstrip-patch antenna. The proposed system can also be used for a wireless positioning system
Near-Field UHF RFID Transponder with a Screen-Printed Graphene Antenna
As a method of producing RFID tags, printed graphene provides a low-cost and
eco-friendly alternative to the etching of aluminum or copper. The high
resistivity of graphene, however, sets a challenge for the antenna design. In
practice, it has led to using very large antennas in the UHF RFID far field
tags demonstrated before. Using inductive near field as the coupling method
between the reader and the tag is an alternative to the radiating far field
also at UHF. The read range of such a near field tag is very short, but, on the
other hand, the tag is extremely simple and small. In this paper, near field
UHF RFID transponders with screen-printed graphene antennas are presented and
the effect of the dimensions of the tag and the attachment method of the
microchip studied. The attachment of the microchip is an important step of the
fabrication process of a tag that has its impact on the final cost of a tag. Of
the tags demonstrated, even the smallest one with the outer dimensions of 21 mm
* 18 mm and the chip attached with isotropic conductive adhesive (ICA) was
readable from a distance of 10 mm with an RF power marginal of 19 dB, which
demonstrates that an operational and small graphene-based UHF RFID tag can be
fabricated with low-cost industrial processes.Comment: 8 pages, 9 figures. IEEE Transactions on Components, Packaging and
Manufacturing Technology, 201
Multi-State Logging Freeze Detection Passive RFID Tags
In this work the design and measurement of a passive UHF RFID smart tag suitable for monitoring and recording critical temperature violations in cold chain management are presented. The tag uses moving parts to detect and log different temperate states without the requirement for transceivers, memory and batteries. A simple mechanical method is proposed whereby a moving metallic plate is trapped in one of 4 possible positions by specific environmental temperatures whereby inducing a permanent state based change in the passive RFID tag response. The latched product critical temperature violations can be monitored via the read power required to turn on the tag transponder chip which differs in each state
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