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...

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Bibliographic Details
Authors: Herrojo, Cristian|||0000-0003-1934-9993; Muela, Francisco Javier; Mata Contreras, Francisco Javier|||0000-0001-6116-8681; Paredes Marco, Ferran|||0000-0002-7252-1169; Martín, Ferran|||0000-0002-1494-9167
Format: Article
Publication date:2019
Country:España
Institution:Universitat Autònoma de Barcelona
Repository:Dipòsit Digital de Documents de la UAB
Language:English
OAI Identifier:oai:ddd.uab.cat:221406
Online Access:https://ddd.uab.cat/record/221406
https://dx.doi.org/urn:doi:10.1109/JSEN.2019.2895015
Access Level:Open access
Keyword:Displacement sensors
Velocity sensors
Chipless-RFID
Microwave encoders
Motion control
Description
Summary: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 read.