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

Double-stub loaded microstrip line reader for very high data density microwave encoders

Compact and high-data density microwave encoders useful for motion control and near-field chipless radio frequency identification (chipless-RFID) applications are proposed in this paper. The encoders are chains of metallic strips etched on a dielectric substrate. The reader consists of a microstrip line loaded with a pair of identical open-ended folded stubs located at different positions and oriented face-to-face by their extremes. By displacing the encoder over the extremes of the stubs, interstub coupling arises when a strip is located on top of the stubs, thereby generating two transmission zeros (rather than one) in the frequency response of the line. Thus, the presence of a strip on top of the face-to-face stubs produces a variation in the transmission coefficient of the line, which in turn can be detected by feeding the line with a harmonic signal, conveniently tuned. Encoder motion generates an amplitude modulated (AM) signal at the output port of the line with peaks, or dips, separated by a time distance dictated by the relative velocity between the reader and the encoder. Moreover, by making certain strips of the chain inoperative (e.g., by cutting them), it is possible to encode information that can be read as the absence (logic state "1") or presence (logic state "0") of peaks, or dips, at predefined positions in the output AM signal of the reader line. Since short strips suffice to generate interstub coupling, unprecedented data density per surface (DPS = 26.04 bit/cm 2 ) is obtained, as revealed by the implementation of 6.4 mm × 60 mm 100-bit encoder

Contribution au développement de tags chipless et des capteurs à codage dans le domaine temporel

La RFID sans puce, en raison du très faible coût des tags, a ouvert une nouvelle voie pour les systèmes d'identification. Les étiquettes RFID sans puce fonctionnant dans le domaine temporel ont l'avantage d'être compatibles avec de grandes distances de lecture, de l'ordre de quelques mètres, et de pouvoir fonctionner dans les bandes de fréquence ISM. Cependant, les tags de ce type développés jusqu'à lors n'offraient qu'une faible capacité de codage. Cette thèse propose une nouvelle méthode pour augmenter la capacité de codage des tags fonctionnant dans le domaine temporel en utilisant des C-sections, c'est-à-dire des lignes de transmission repliées de manière à avoir des zones fortement couplées, ce qui leur donne un caractère dispersif. Une autre approche basée sur une technique multi-couches a également été introduite de façon à augmenter considérablement la capacité de codage. Pour terminer, la preuve de concept d'un tag-capteur d'humidité, basé sur l'utilisation de nano fils de silicium, est également présentée.Chipless RFID tags, owing to their low cost, have opened a new way to the identification systems. Chipless RFID tags operating in the time domain have the advantage of being compatible with large reading distances of the order of a few meters, and also can operate in the ISM frequency bands. However, time domain tags developed until now offer poor coding capacity. This thesis proposes a new method to increase the coding capacity of tags operating in time domain by using C-sections, i.e. the transmission lines are folded so as to have tightly coupled zones that give them a dispersive nature. Another approach based on a multi-layer technique was also introduced, in order to increase the coding capacity considerably. Finally, the proof of concept of a humidity sensor tag based on silicon nanowires is also presented.SAVOIE-SCD - Bib.électronique (730659901) / SudocGRENOBLE1/INP-Bib.électronique (384210012) / SudocGRENOBLE2/3-Bib.électronique (384219901) / SudocSudocFranceF

Strategies to enhance the data density in synchronous electromagnetic encoders

Altres ajuts: ICREA awardIn this paper, we report two different strategies to enhance the data density in electromagnetic encoders with synchronous reading. One approach uses a periodic chain of rectangular metallic patches (clock chain) that determines the encoder velocity, and dictates the instants of time for retrieving the bits of the identification (ID) code. However, contrary to previous electromagnetic encoders, the ID is inferred at both the rising and the falling edges of the clock signal generated by the clock chain. Moreover, the bits of information are not given by the presence or absence of metallic patches at their predefined positions in the so-called ID code chain. With this novel encoding system, a bit state corresponding to a certain instant of time is identical to the previous bit state, unless there is a change in the envelope function of the ID code signal, determined by the additional non-periodic ID code chain. The other encoding strategy utilizes a single chain of C-shaped resonators, and encoding is achieved by considering four different resonator dimensions, corresponding to four states and, hence, to two bits per resonator of the chain. Thus, with these two strategies, the data density is twice the one achievable in previously reported synchronous electromagnetic encoders

Chipless RFID based on group delay encoding

International audienceA two bit planar chipless RFID tag based on group delay encoding has been presented in this paper. This chipless tag encodes data in the phase signature. The data encoding has been done by using C-sections formed by coupling the cascaded transmission line sections at alternative ends. The tag produces two different delays for two specific frequencies corresponding to the two different lengths of the transmission line sections. A measurable amount of delay has been obtained. The new approach has been validated with simulation results in frequency and temporal domain and with measurement results in frequency domain