Chipless Radio Frequency Identification Tag Research Articles

Polarization independent chipless RFID tag

ABSTRACTFully printable polarization independent frequency domain chipless radiofrequency identification tag using the harmonic separation capability of Stepped Impedance Resonator is proposed. The data are encoded either using the magnitude or group delay of the backscattered signal. The data encoding capacity of the tag is enhanced using Frequency Shift Coding technique. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:1889–1894, 2015

Angle-Based Chipless RFID Tag With High Capacity and Insensitivity to Polarization

This paper presents a novel angle-based chipless radio frequency identification (RFID) tag with high capacity that is polarization-independent. Its scatterer is designed to be V-shaped. It encodes data using the space angle between two arms of the V-shape and is identified by measuring the scattered field in two orthogonal polarization directions. Even if it is tilted, the tag can be identified. The advantage of angle-based tag is that every element can encode three-bit data. This is helpful to get higher capacity. Also, for different codes of one element, the proposed tag uses the same spectrum. This is beneficial to improve the efficiency of the spectrum. First, the tag using the uniform impedance resonator (UIR) is designed. Then, the UIR chipless tag is reformed as stepped impedance resonator (SIR) tag to suppress the second harmonic. The realized tags operate in the frequency range 1.83-2.15 GHz and the identification errors are less than 3.9°. Every element of the realized tags can carry 3 bits of coding information.

On the application of the EM-imaging for chipless RFID tags

The electromagnetic (EM) imaging technique at mm-band 60 GHz is proposed for data encoding purpose in the chipless Radio Frequency Identification (RFID) systems. The fully printable chipless RFID tag comprises tiny conductive EM polarizers to create high cross-polar radar cross-section. Synthetic aperture radar approach is applied for formation of the tag's EM-image and revealing the tag's content. The achieved high data encoding capacity of 2 bits/cm2in this technique based on a fully printable tag is very convincing for many applications. The system immunity to multipath interference, bending effect, and printing inaccuracy suggests huge potentials for low-cost item tagging. Tags are also readable through a tick paper envelop; hence secure identification is provided by the proposed technique.

Chipless RFID tags and sensors: a review on time-domain techniques

In the past few years Radio Frequency Identification(RFID)has grown to be one of the most popular technologies in the area of identification systems. Following a brief survey of RFID systems, this paper provides a technical review of work undertaken in the field of time-domain chipless RFID tags and sensors. This paper aims not only to address the chipless tags which use Time Domain Reflectometry (TDR) concept for data encoding but also for the use of Ultra-Wideband Impulse-Radar (UWB-IR) as a time-domain measurement technique. The penultimate section intends to focus on time-domain reading setups and finally, a brief comparison between this method and other chipless techniques is provided.

Spectral signature-encoded chipless RFID tag with planar multiresonators

The paper discusses the development of a spectral signature-based chipless Radio Frequency Identification tag using multiple spurline resonators to encode data. Bistatic detection approach is used to decode the tag identity using either the amplitude or the phase of the spectral signature in a spurline resonator. The tag comprises two cross-polarized transmitting and receiving wideband monopole antennas connected to the multiple spurline resonators. The prototype of the tag is fabricated on a substrate C-MET/LK4.3 of dielectric constant 4.3 and loss tangent 0.0018. The measured results show that group delay response can also be used to decode the tag’s identity.

A Space–Time–Frequency Anticollision Algorithm for Identifying Chipless RFID Tags

In this paper, the short-time matrix pencil method (STMPM) is efficiently employed as a time-frequency analysis methodology for the identification of multiple chipless radio-frequency identification (RFID) tags presented in the main beam of the reader antenna. Each tag represents a unique ID in the backscattered signal. Here, the data are embedded on the tag as the complex natural resonances (CNRs) of the structure. In the cases where more than one tag exist in the main beam of the reader antenna, the frequency-domain response is not sufficient to successfully distinguish the IDs of the tags. By applying the STMPM technique to the time-domain response, the poles and their residues are obtained at each snapshot of time. In order to obtain the exact values of the turn-on times of the poles, which are the roundtrip time of the tags to the antenna, high resolution in the time domain is needed which deteriorates the resolution in the frequency domain. Using mathematical descriptions, a simple formulation is derived which exhibits a duality between late-time response in the time domain and early-time response in the frequency domain. Therefore, a space-frequency representation can be simply obtained from the application of the short-frequency matrix pencil method (SFMPM) to the frequency-domain response of the tags. By possessing the exact values of the turn-on times and pole/residues of the tags, their backscattered responses can be reconstructed and associated IDs can be retrieved. With the proposed method in this paper, some scenarios are studied and discussed. As an experimental result, three 3-bit tags with different IDs (ID1:101, ID2:111, and ID3:011) are fabricated and placed away from each other. Exploiting the presented technique, the IDs of the tags and their locations are successfully distinguished. The simulation results are validated by the measured ones. The ranging error obtained by the proposed method is less than 1 cm.

Development of a Low Cost Printable Chipless RFID Humidity Sensor

A novel low-cost chipless radio frequency identification tag sensor is presented. The tag sensor provides identification data as well as monitors relative humidity (RH) of tagged objects. The tag sensor is made of passive microwave circuit that uses humidity sensitive polymer material for RH sensing. The aim of this paper is to investigate RF sensing properties of moisture absorbing polymer polyvinyl alcohol at microwave frequency. In addition, frequency shifting technique is used to encode data bits for high data capacity. The overall size of the proposed tag sensor is 15 mm × 6.8 mm and has 6 bit data capacity for ID generation and single bit for humidity sensing. Results presented here show ~ 607 MHz frequency deviation for 50% RH increase. The tag sensor has potential to be printed on flexible laminates such as plastic and paper for ultra-low cost item level tagging and ubiquitous sensing.

On the detection of chipless RFID through signal space representation

paper presents a novel approach to model and represent chipless radio-frequency identification (RFID) frequency signatures. The approach involves the geometrical representation of chipless RFID frequency signatures in a signal space. A small set of orthonormal basis functions is derived using singular value decomposition in order to represent the 2b possible tag signatures of a b-bit chipless tag. Each tag signature is represented as a point in an L-dimensional signal space, and minimum distance detection is used to extract the information bit sequence of the tag. Detection error probability is also examined through analytical derivations and Monte Carlo simulation. A set of 3-bit tags were fabricated to validate the approach. Experimental results show that the new approach is capable of accurately detecting information contained in chipless RFID tags. This approach offers a solid mathematical framework for developing novel detection methods for chipless tags.

Chipless RFID tags fabricated by fully printing of metallic inks

This paper reviews recent advances in fully printed chipless radio frequency identification (RFID) technology with special concern on the discussion of coding theories, ID generating circuits, and tag antennas. Two types of chipless tags, one based on time-domain reflections and the other based on frequency domain signatures, are introduced. To enable a fully printed encoding circuit, linearly tapering technique is adopted in the first type of tags to cope with parasitic resistances of printed conductors. Both simulation and measurement efforts are made to verify the feasibility of the eight-bit fully printed paper-based tag. In the second type of tags, a group of LC tanks are exploited for encoding data in frequency domain with their resonances. The field measurements of the proof-of-concept of the tag produced by toner-transferring process and flexible printed circuit boards are provided to validate the practicability of the reconfigurable ten-bit chipless RFID tag. Furthermore, a novel RFID tag antenna design adopting linearly tapering technique is introduced. It shows 40 % save of conductive ink materials while keeping the same performance for conventional half-wave dipole antennas and meander line antennas. Finally, the paper discusses the future trends of chipless RFID tags in terms of fabrication cost, coding capacity, size, and reconfigurability. We see that, coupled with revolutionary design of low-cost tag antennas, fabrication/reconfiguration by printing techniques, moving to higher frequencies to shrink tag sizes and reduce manufacturing cost, as well as innovation in ID generating circuits to increase coding capacities, will be important research topics towards item-level tracking applications of chipless RFID tags.

On the Detection of Frequency-Spectra-Based Chipless RFID Using UWB Impulsed Interrogation

A novel approach is presented to accurately estimate the resonant features of a multipatch backscatter-based chipless radio frequency identification (RFID) tag. An ultra-wideband impulse radar (UWB-IR)-based reader interrogates the chipless tag with a UWB pulse, and the received backscatter is analyzed in the time domain. The key components constituting the backscattered signal, the structural mode, and the antenna mode are identified, and their spectral content are analyzed. Analysis shows that the antenna mode backscatter contains the information carrying signal while the structural mode backscatter contains no information about the tag. A semi-analytical model is developed to explain the behavior of the signal backscattered from the chipless RFID tag. Simulation and semi-analytical results are validated by experimental measurements obtained in an anechoic chamber environment using a 4-b multipatch chipless RFID tag. The new method does not rely on calibration tags for operation and has a greater degree of freedom in the orientation of tags with respect to a reader. A novel method, selective spectral interrogation (SSI), that uses a set of interrogation pulses to extract information bits stored in the spectral signature of the chipless tag is also introduced.

Design of fully printable and configurable chipless RFID tag on flexible substrate

AbstractThis article presents the design and implementation of a chipless radio frequency identification (RFID) tag on flexible substrate.The tag is designed based on the sympathetic oscillations of multiple LC (inductor–capacitor) circuits that possess distinct resonant frequencies. Information is encoded by controlling placement of these resonant frequencies. To trade off the readability and size of the tag, the optimizations including capacitor placements and different LC combinations are studied. The tag is then realized onto flexible polyimide substrate using toner‐transferring process. The detection system is also constructed and used to measure the proposed tag. The measurement results show that the tag can provide an excellent readability more than 20 cm reading range. In addition, this tag is fully printable and configurable, hence making it more feasible and considerably cheaper to be used. This tag can provide a meaningful approach toward the realization of ultralow‐cost RFID tags attached onto low‐value items. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:226–230, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26499

Embedded Singularity Chipless RFID Tags

Every structure scatters an impulse plane wave in a unique fashion. The structural information of an object can be extracted by analyzing the late-time scattered field as the impulse-response of the structure. The late-time scattered field, which represents the source-free response of the structure, contains a summation of damped sinusoids. The frequency and damping factor of these damped sinusoids are uniquely associated with the structural information, and can be used to identify an unknown object. We propose to create uniquely identifiable scattered fields from an object by incorporating “notches” in the structure giving rise to specific damped sinusoids in the source-free scattered field of the structure. In this manner, data can be embedded into the structure of an object which is detectable using electromagnetic waves, allowing a metallic object to serve as a chipless radio-frequency identification tag (RFID). Data is encoded as complex natural resonant frequencies (referred to as poles) in the structure and is retrieved from the scattered field. Data retrieval is based on Singularity Expansion Method (SEM) analysis using target identification techniques. Each complex-frequency pole provides two-dimensional data (real and imaginary) which can be extracted from the late-time impulse response of the structure using a numerical technique such as the Matrix Pencil Method. We have designed and prototyped a 6-bit (3-pole) tag. The tag is analyzed using simulations and measurements. The tag is successfully read remotely via its scattered fields. The measured data are compared with simulation, and are in close agreement.

Configurable ink‐jet‐printed RFID tag on paper substrate for low cost and green applications

AbstractThe letter presents the design, fabrication, and measurement of a configurable radio frequency identification (RFID) tag based on time‐domain reflections. The tag circuit contains a microstrip line (ML) that propagates radio frequency (RF) signals, and a group of capacitors that introduce impedance discontinuities to encode binary codes. The configurability of the tag circuit is allowed by connecting the nearby‐placed capacitors with the ML. Ink‐jet printing technology is employed to implement the layout of the proposed tag on paper substrate. To overcome the limitations of printed metallic tracks, a linearly tapering technique is proposed. With this technique, a four‐bit configurable passive chipless RFID tag is realized. Both time‐domain reflectometry (TDR) measurements and ultrawideband (UWB) characterizations were conducted for the proposed tag, and the results are in good consistence with the simulation ones from the circuit simulator advanced design system (ADS). Owing to its low cost fabrication and environmentally friendly nature, the proposed tag has great potential to be widely employed in low‐end RFID applications. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:2781–2786, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26412

Inkjet printing and low power laser annealing of silver nanoparticle traces for the realization of low resistivity lines for flexible electronics

We report on the realization of low resistance silver lines by inkjet printing of a commercial silver-based ink on a flexible kapton substrate and subsequent low energy laser annealing to promote nanoparticle coalescence. Our approach resulted in low resistivity values, yet using a low-silver product, around 22 wt.%. Traditional hot-plate annealing processes were compared also. The approach is of particular interest for the realization of electronic parts such as passive and chipless radio frequency identification tags with fully inkjet printed inductors and capacitors – that we also demonstrated.