Chipless-RFID : a review and recent developments

In this paper, a review of the state-of-the-art chipless radiofrequency identification (RFID) technology is carried out. This recent technology may provide low cost tags as long as these tags are not equipped with application specific integrated circuits (ASICs). Nevertheless, chipless-RFID presents a series of technological challenges that have been addressed by different research groups in the last decade. One of these challenges is to increase the data storage capacity of tags, in order to be competitive with optical barcodes, or even with chip-based RFID tags. Thus, the main aim of this paper is to properly clarify the advantages and disadvantages of chipless-RFID technology. Moreover, since the coding information is an important aspect in such technology, the di_erent coding techniques, as well as the main figures of merit used to compare di_erent chipless-RFID tags, will be analyzed

Frequency-spectra-based high coding capacity chipless RFID using an UWB-IR approach

A novel methodology is proposed to reliably predict the resonant characteristics of a multipatch backscatter-based radio frequency identification (RFID) chipless tag. An ultra-wideband impulsion radio (UWB-IR)-based reader interrogates the chipless tag with a UWB pulse, and analyzes the obtained backscatter in the time domain. The RFID system consists of a radar cross-section (RCS)-based chipless tag containing a square microstrip patch antenna array in which the chipless tag is interrogated with a UWB pulse by an UWB-IR-based reader. The main components of the backscattered signal, the structural mode, and the antenna mode were identified and their spectral quality was evaluated. The study revealed that the antenna-mode backscatter includes signal carrying information, while the structural mode backscatter does not include any tag information. The simulation findings were confirmed by experimental measurements obtained in an anechoic chamber environment using a 6-bit multipatch chipless RFID tag. Finally, the novel technique does not use calibration tags and can freely orient tags with respect to the reader.This research work was supported by FCT through grant SFRH/BD/116554/2016 and by the Center for Microelectromechanical Systems Research CMEMS-UMinho

Advanced Radio Frequency Identification Design and Applications

Radio Frequency Identification (RFID) is a modern wireless data transmission and reception technique for applications including automatic identification, asset tracking and security surveillance. This book focuses on the advances in RFID tag antenna and ASIC design, novel chipless RFID tag design, security protocol enhancements along with some novel applications of RFID

Passively-coded embedded microwave sensors for materials characterization and structural health monitoring (SHM)

Monitoring and maintaining civil, space, and aerospace infrastructure is an ongoing critical problem facing our nation. As new complex materials and structures, such as multilayer composites and inflatable habitats, become ubiquitous, performing inspection of their structural integrity becomes even more challenging. Thus, novel nondestructive testing (NDT) methods are needed. Chipless RFID is a relatively new technology that has the potential to address these needs. Chipless RFID tags have the advantage of being wireless and passive, meaning that they do not require a power source or an electronic chip. They can also be used in a variety of sensing applications including monitoring temperature, strain, moisture, and permittivity. However, these tags have yet to be used as embedded sensors. By embedding chipless RFID tags in materials, materials characterization can be performed via multi-bit sensing; that is, looking at how the multi-bit code assigned to the response of the tag changes as a function of material. This thesis develops this method through both simulation and measurement. In doing so, a new coding method and tag design are developed to better support this technique. Furthermore, inkjet-printing is explored as a manufacturing method for these tags and various measurement methods for tags including radar cross-section and microwave thermography are explored --Abstract, page iii

Near-field chipless-RFID system with high data capacity for security and authentication applications

A high data capacity chipless radio frequency identification (chipless-RFID) system, useful for security and authentication applications, is presented in this paper. Reading is based on the near-field coupling between the tag, a chain of identical split-ring resonators (SRRs) printed on a (typically flexible) dielectric substrate (e.g., liquid crystal polymer, plastic, and paper), and the reader. Encoding is achieved by the presence or absence of SRRs at predefined (equidistant) positions in the chain, and tag identification (ID) is based on sequential bit reading. Namely, the tag must be longitudinally displaced, at short distance, over the reader, a microstrip line loaded with an SRR and fed by a harmonic signal. By this means, the harmonic signal is amplitude modulated, and the (ID) code is contained in the envelope function, which can be obtained by means of an envelope detector. With this system, tag reading requires proximity with the reader, but this is not an issue in many applications within the domain of security and authentication (e.g., secure paper for corporate documents and certificates). Several circularly shaped 40-bit encoders (implemented in a commercial microwave substrate), and the corresponding reader, are designed and fabricated as proof-of-concept demonstrators. Strategies for programming the tags and a first proof-of-concept chipless-RFID tag fabricated on plastic substrate through inkjet printing are included in this paper

Desenvolvimento de sistema de radiofrequência para identificação de cédulas monetárias e documentos

Orientador: Hugo Enrique Hernández-FigueroaDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de ComputaçãoResumo: Este trabalho descreve o desenvolvimento de um sistema de radiofrequência, eficaz e de baixo custo, para identificação de cédulas monetárias e documentos com a intenção de evitar falsificações. O sistema proposto é baseado nas tecnologias de linha de microfita e RFID sem chip, porém, a identificação é feita através do contato do objeto com a leitora. Para que essa identificação ocorra, na leitora, ressoadores em formato espiral são dispostos próximos a uma linha de transmissão, cada ressoador representando um bit de dado, e ressoam livremente até que uma cédula ou documento seja colocada em contato e devidamente alinhada. Cada cédula ou documento deve possuir uma marca metálica impressa em camada interna, pois dificulta falsificações e as ondas eletromagnéticas conseguem atravessar o papel, de forma que cada marca defina o código binário de cada objeto, uma vez que essas marcas metálicas suprimem as ressonâncias dos ressoadores situados na leitora. Em outras palavras, as marcas metálicas transformam o estado do bit de dado, bit 0 ou 1, correspondendo aos estados de presença e ausência de ressonância, respectivamente. O sistema também tem potencial para aumento do volume de codificação de dados com a possibilidade do sistema ternário, quando as ressonâncias possuem três estados. Resultados de simulações e resultados de medições também são apresentados neste trabalhoAbstract: This work describes the development of a low-cost and efficient radiofrequency system for banknotes and documents identification intending to avoid counterfeiting. The proposed system is based on the microstrip and chipless RFID technologies; however, the identification is carried out through the contact of the object with the reader. In order to make this possible, the spiral resonators in the reader are placed next to a transmission line, each resonator represents a data bit, they resonate freely until a banknote or a document is placed and aligned properly. Each banknote or document must have a metallic mark printed on its inner layer, because it makes falsification difficult and the electromagnetic waves can cross the paper, in such a way that each metallic mark establishes a binary code. The metallic marks suppress the resonances of the resonators located in the reader. In other words, the marks can change the bits state, 0 or 1, corresponding to the presence and absence of resonance, respectively. The system also has the potential to increase the volume of data encoding with the possibility of the ternary system, when the resonances have three states. Simulation and measurement results are also presented in this workMestradoTelecomunicações e TelemáticaMestre em Engenharia ElétricaCAPE

High-density microwave encoders for motion control and near-field chipless-RFID

A novel microwave system for measuring linear displacements and velocities with sub-millimeter resolution and for the implementation of near-field chipless radiofrequency identification (chipless-RFID) systems with very high data capacity is presented. The system is based on a reader, consisting of a half-wavelength straight resonator coupled (through capacitor gaps) to a pair of access lines, and a microwave encoder, in relative motion to the reader and consisting of a linear chain of strips orthogonally oriented to the chain axis. By displacing the encoder over the half-wavelength resonator of the reader, with the encoder strips parallel oriented to the reader axis, the relative velocity and position between the encoder and the reader can be inferred. For that purpose, the reader is fed by a harmonic signal tuned to the resonance frequency that results when an encoder strip is perfectly aligned with the reader. The encoder motion amplitude modulates the feeding signal at the output port, and both the position and the velocity are measured from the peaks, or dips, of the resulting envelope function. Moreover, by making certain strips inoperative, the system can be used for coding purposes. Due to the small period of the encoder (0.6 mm), a high per-unit-length data density in these near-field chipless-RFID tags (i.e., 16.66 bits/cm) is achieved. To illustrate the functionality and potential of the approach, 100-bit chipless-RFID tags with various ID codes are implemented and rea

Chipless Wireless High-Temperature Sensing in Time-Variant Environments

The wireless sensing of various physical quantities is demanded in numerous applications. A usual wireless sensor is based on the functionality of semiconductor Integrated Circuits (ICs), which enable the radio communication. These ICs may limit the application potential of the sensor in certain specific applications. One of these applications stands in the focus of this thesis: the operation in harsh environments, e.g., at high temperatures above 175°C, where most available sensors fail. Chipless wireless sensors are researched to exceed such chip-based limitations. A chipless sensor is setup as an entirely electro-magnetic circuit, and uses passive Radio Frequency (RF) backscatter principles to encode and transmit the measured value. Chipless sensors that target harsh environment operation are facing two important challenges: First, the disturbance by clutter, caused by time-variant reflections of the interrogation signal in the sensor environment and second, the design of suitable measurand transducers. These challenges are addressed in the thesis. To overcome the first challenge, three basic chipless sensor concepts feasible for operation in clutter environments are introduced. The concepts are realized by demonstrator designs of three temperature sensors and are proofed by wireless indoor measurements. A channel estimation method is presented that dynamically estimates and suppresses clutter signals to reduce measurement errors. To overcome the second challenge, measurand-sensitive dielectric materials are used as measurement transducers, and are being characterized by a novel high-temperature microwave dielectric characterization method. Complex permittivity characterization results in temperatures up to 900°C are presented. Finally, in-depth description and discussion of the three chipless concepts is given as well as a performance comparison in wireless indoor measurement scenarios. The first concept is based on polarization separation between the wanted sensor backscatter signal and unwanted clutter. The second concept separates tag and clutter signals in the frequency domain by using harmonic radar. The third concept exploits the slow decay of high-Q resonances in order to achieve the desired separation in time domain. This concept’s realization is based on dielectric resonators and has demon- strated the capability of wirelessly measuring temperatures up to 800°C without requiring an optical line-of-sight. This performance significantly exceeds temperature- and detection-limitations of commercially available sensors at the current state-of-the-art

Design of an Ultra-wideband Radio Frequency Identification System with Chipless Transponders

The state-of-the-art commercially available radio-frequency identification (RFID) transponders are usually composed of an antenna and an application specific integrated circuit chip, which still makes them very costly compared to the well-established barcode technology. Therefore, a novel low-cost RFID system solution based on passive chipless RFID transponders manufactured using conductive strips on flexible substrates is proposed in this work. The chipless RFID transponders follow a specific structure design, which aim is to modify the shape of the impinged electromagnetic wave to embed anidentification code in it and then backscatter the encoded signal to the reader. This dissertation comprises a multidisciplinary research encompassing the design of low-cost chipless RFID transponders with a novel frequency coding technique, unlike usually disregarded in literature, this approach considers the communication channel effects and assigns a unique frequency response to each transponder. Hence, the identification codes are different enough, to reduce the detection error and improve their automatic recognition by the reader while working under normal conditions. The chipless RFID transponders are manufactured using different materials and state-of-the-art mass production fabrication processes, like printed electronics. Moreover, two different reader front-ends working in the ultra-wideband (UWB) frequency range are used to interrogate the chipless RFID transponders. The first one is built using high-performance off-theshelf components following the stepped frequency modulation (SFM) radar principle, and the second one is a commercially available impulse radio (IR) radar. Finally, the two readers are programmed with algorithms based on the conventional minimum distance and maximum likelihood detection techniques, considering the whole transponder radio frequency (RF) response, instead of following the commonly used approach of focusing on specific parts of the spectrum to detect dips or peaks. The programmed readers automatically identify when a chipless RFID transponder is placed within their interrogation zones and proceed to the successful recognition of its embedded identification code. Accomplishing in this way, two novel fully automatic SFM- and IRRFID readers for chipless transponders. The SFM-RFID system is capable to successfully decode up to eight different chipless RFID transponders placed sequentially at a maximum reading range of 36 cm. The IR-RFID system up to four sequentially and two simultaneously placed different chipless RFID transponders within a 50 cm range.:Acknowledgments Abstract Kurzfassung Table of Contents Index of Figures Index of Tables Index of Abbreviations Index of Symbols 1 Introduction 1.1 Motivation 1.2 Scope of Application 1.3 Objectives and Structure Fundamentals of the RFID Technology 2.1 Automatic Identification Systems Background 2.1.1 Barcode Technology 2.1.2 Optical Character Recognition 2.1.3 Biometric Procedures 2.1.4 Smart Cards 2.1.5 RFID Systems 2.2 RFID System Principle 2.2.1 RFID Features 2.3 RFID with Chipless Transponders 2.3.1 Time Domain Encoding 2.3.2 Frequency Domain Encoding 2.4 Summary Manufacturing Technologies 3.1 Organic and Printed Electronics 3.1.1 Substrates 3.1.2 Organic Inks 3.1.3 Screen Printing 3.1.4 Flexography 3.2 The Printing Process 3.3 A Fabrication Alternative with Aluminum or Copper Strips 3.4 Fabrication Technologies for Chipless RFID Transponders 3.5 Summary UWB Chipless RFID Transponder Design 4.1 Scattering Theory 4.1.1 Radar Cross-Section Definition 4.1.2 Radar Absorbing Material’s Principle 4.1.3 Dielectric Multilayers Wave Matrix Analysis 4.1.4 Frequency Selective Surfaces 4.2 Double-Dipoles UWB Chipless RFID Transponder 4.2.1 An Infinite Double-Dipole Array 4.2.2 Double-Dipoles UWB Chipless Transponder Design 4.2.3 Prototype Fabrication 4.3 UWB Chipless RFID Transponder with Concentric Circles 4.3.1 Concentric Circles UWB Chipless Transponder 4.3.2 Concentric Rings UWB Chipless RFID Transponder 4.4 Concentric Octagons UWB Chipless Transponders 4.4.1 Concentric Octagons UWB Chipless Transponder Design 1 4.4.2 Concentric Octagons UWB Chipless Transponder Design 2 4.5 Summary 5. RFID Readers for Chipless Transponders 5.1 Background 5.1.1 The Radar Range Equation 5.1.2 Range Resolution 5.1.3 Frequency Band Selection 5.2 Frequency Domain Reader Test System 5.2.1 Stepped Frequency Waveforms 5.2.2 Reader Architecture 5.2.3 Test System Results 5.3 Time Domain Reader 5.3.1 Novelda Radar 5.3.2 Test System Results 5.4 Summary Detection of UWB Chipless RFID Transponders 6.1 Background 6.2 The Communication Channel 6.2.1 AWGN Channel Modeling and Detection 6.2.2 Free-Space Path Loss Modeling and Normalization 6.3 Detection and Decoding of Chipless RFID Transponders 6.3.1 Minimum Distance Detector 6.3.2 Maximum Likelihood Detector 6.3.3 Correlator Detector 6.3.4 Test Results 6.4 Simultaneous Detection of Multiple UWB Chipless Transponders 6.5 Summary System Implementation 7.1 SFM-UWB RFID System with CR-Chipless Transponders 7.2 IR-UWB RFID System with COD1-Chipless Transponders 7.3 Summary Conclusion and Outlook References Publications Appendix A RCS Calculation Measurement Setups Appendix B Resistance and Skin Depth Calculation Appendix C List of Videos Test Videos Consortium Videos Curriculum Vita