P4J-1 Design Parameters for SAW Multi-Tone Frequency Coded Reflectors

et al. 2019

Sensors

108

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 different coding techniques, as well as the main figures of merit used to compare different chipless-RFID tags, will be analyzed.

Section: Chipless-rfid Tags Based On Time Domainmentioning

confidence: 99%

Chipless-RFID: A Review and Recent Developments

et al. 2019

Sensors

108

“…Chipless-RFID systems are based on two main approaches: (i) time domain based systems [8][9][10][11][12][13][14][15][16][17] and (ii) frequency domain based systems [2,3,[18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37]. In chipless-RFID systems based on the former approach, tag reading is carried out through time domain reflectometry (TDR).…”

Section: Introductionmentioning

confidence: 99%

Near-field chipless-RFID tags with sequential bit reading implemented in plastic substrates

Journal of Magnetism and Magnetic Materials

et al. 2018

Chipless radiofrequency identification (chipless-RFID) systems based on nearfield coupling between the tag and the reader and sequential bit reading, with tags implemented on plastic substrates, are presented in this paper. In the proposed system, the tag is a set of identical resonant elements (S-shaped split ring resonators-S-SRRs), inkjet-printed on a plastic substrate (PEN), forming a resonator chain. The presence or absence of resonant elements at predefined and equidistant positions in the chain determines the logic state '1' and '0', respectively, associated with each resonant element. The reader is a coplanar waveguide (CPW) transmission line fed by a harmonic signal tuned to the resonance frequency of the resonant elements of the chain. Tag reading is achieved by displacing the chain of resonant elements above the CPW transmission line, in close proximity to it, so that near-field coupling between the CPW transmission line and the resonant elements of the tag results. By this means, the injected carrier signal is amplitude modulated, provided the transmission coefficient of the line varies with the presence or absence of resonant elements in the chain, and the identification (ID) code is contained in the envelope function. The functionality of the proposed system, with 10-bit tags occupying an area of 1.35 cm 2 (corresponding to an information density of 7.4 bit/cm 2), is demonstrated.

“…There are two main approaches to the implementation of chipless-RFID systems: those based on the time domain [ 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 ], and those based on the frequency domain [ 3 , 4 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 ]. Most systems within the former approach are based on time-domain reflectometry (TDR), where the identification (ID) code is given by the echoes generated by the tag (a delay line with reflectors at certain positions) to a narrow pulse (interrogation signal).…”

Section: Introductionmentioning

confidence: 99%

“…Most systems within the former approach are based on time-domain reflectometry (TDR), where the identification (ID) code is given by the echoes generated by the tag (a delay line with reflectors at certain positions) to a narrow pulse (interrogation signal). Despite the fact that TDR tags implemented on surface acoustic wave (SAW) technology are competitive [ 9 , 12 , 14 , 15 , 16 ], such tags are not compatible with standard printing processes. On the other hand, attempts to implement TDR-based tags on fully planar technology have been successful, but the achieved number of bits has been very limited [ 11 , 13 , 17 ].…”

Section: Introductionmentioning

confidence: 99%

Near-Field Chipless Radio-Frequency Identification (RFID) Sensing and Identification System with Switching Reading

et al. 2018

Sensors

A chipless radio-frequency identification (chipless-RFID) and sensing system, where tags are read by proximity (near-field) through a switch, is presented. The tags consist of a set of identical resonant elements (split-ring resonators or SRRs), printed or etched at predefined and equidistant positions, forming a linear chain, each SRR providing a bit of information. The logic state (‘1’ or ‘0’) associated with each resonator depends on whether it is present or not in the predefined position. The reader is an array of power splitters used to feed a set of SRR-loaded transmission lines (in equal number to the number of resonant elements, or bits, of the tag). The feeding (interrogation) signal is a harmonic (single-tone) signal tuned to a frequency in the vicinity of the fundamental resonance of the SRRs. The set of SRR-loaded lines must be designed so that the corresponding SRRs are in perfect alignment with the SRRs of the tag, provided the tag is positioned on top of the reader. Thus, in a reading operation, as long as the tag is very close to the reader, the SRRs of the tag modify (decrease) the transmission coefficient of the corresponding reader line (through electromagnetic coupling between both SRRs), and the amplitude of the output signal is severely reduced. Therefore, the identification (ID) code of the tag is contained in the amplitudes of the output signals of the SRR-loaded lines, which can be inferred sequentially by means of a switching system. Unlike previous chipless-RFID systems based on near-field and sequential bit reading, the tags in the proposed system can be merely positioned on top of the reader, conveniently aligned, without the need to mechanically place them across the reader. Since tag reading is only possible if the tag is very close to the reader, this system can be also used as a proximity sensor with applications such as target identification. The proposed chipless-RFID and sensing approach is validated by reading a designed 4-bit tag. For identification purposes, this system is of special interest in applications where a low number of bits suffice, and tag reading by proximity is acceptable (or even convenient). Applications mostly related to secure paper, particularly involving a limited number of items (e.g., exams, ballots, etc.), in order to provide authenticity and avoid counterfeiting, are envisaged. As a proximity sensor, the system may be of use in detecting and distinguishing different targets in applications such as smart packaging.