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Electromagnetic Models for Passive Tag-to-Tag Communications
Full text linkThe UHF passive Radio Frequency Identification
technology generally enables an asymmetric interaction between
the reader and the tag, the latter only being able to respond to
the query of the reader through backscattering modulation. Very
recently some experiments put into evidence the possibility to set
up a tag-to-tag communication by using a simple illuminator.
The key issues and the physical limitation of such a crosslink
are here investigated both theoretically and numerically by
fully accounting for the mutual coupling among the tags, their
radiation properties and the impedance modulation. The analysis
reveals that the cross-link range may be optimized by a proper
design of the tags’ input impedance and that alignment of a
multiplicity of tags could be able to communicate according to
a simple routing strategy
Wireless Crack Monitoring by Stationary Phase Measurements from Coupled RFID Tags
No full textThe possibility to wirelessly monitor the state and the
evolution of cracks is of increasing interest in emerging structural
health monitoring systems. A simple and effective measurement
method considers the placement of two passive radio frequency
identification (RFID) antennas on top of the crack, so that the
crack’s evolution will produce a change of the inter-antenna
coupling and in turn of the phase of the backscattered field. An
ad-hoc design technique, based onto the coupled-modes physics,
permits to maximize the sensor’s sensitivity avoiding, or at least
mitigating, the read range reduction during the evolution of the
displacement that is instead typical of amplitude-oriented RFID
displacement sensors. The proposed idea is demonstrated by
numerical and experimental examples showing the possibility of
sub-millimeter resolution with low-cost devices
Passive RFID Couplets as Wireless Interface for Sensor Applications
No full textRFID tags are renowned for their versatility and low cost. In recent years, applications making use of them are growing in number and maturity level, but still lack in combining both communication and sensing optimal performance. The present work shows how to use a two-port RFID grid (e.g. a couplet of electromagnetically coupled RFID tags) as a general transducer of sensor information, able to transform a variation of the impedance of a load to which it is connected into a remotely-readable phase variation: in such a way, the tags are effectively turned into a wireless interface for the variable load sensor and are moreover able to provide constant antenna matching and hence stable read range
Multi-chip RFID antenna integrating shape-memory alloys for temperature sensing
No full textThis paper proposes a dual-chip UHF tag embedding Shape Memory Alloys (SMA) able to tranform the variation of the tagged item's temperature into a permanent change of antenna radiation features. This event-driven antenna is hence able to selectively activate the embedded microchips according to the temperature above or below a given threshold. A general design methodology for the resulting two-ports tag antenna is here introduced and then applied to prototypes able to work at low (around 0°C) and high (80°C) temperatures. The devices has clear applications in supply chain management as well as general safety assessment
RFID Grids: Part II- Experimentations
No full textThe RFID Grid is a model for generally coupled mul- titudes of tags including single-chip tags in close mutual proximity or a single tag with a plurality of embedded microchips. Some properties of this new entity, useful for passive Sensing and for Se- curity, are the possibility to increase the read-range and to pro- vide responses rather insensitive to the interrogation modalities. These recently introduced issues are here experimented for the first time with many real-world examples comprising multi-chip config- urations designed for improved power scavenging and for passive sensing of things
Passive RFID Couplets as Wireless Interface for Sensor Applications
No full textRFID tags are renowned for their versatility and low
cost. In recent years, applications making use of them are growing
in number and maturity level, but still lack in combining both
communication and sensing optimal performance. The present
work shows how to use a couplet of RFID tags as a general
transducer of sensor information, able to transform a variation of
the impedance of a load to which it is connected into a remotelyreadable
phase variation: in such a way, the tags are effectively
turned into a wireless interface for the variable load sensor and
are moreover able to provide constant antenna matching and
hence stable read range
Antennas as Sensors
No full textThe chapter describes the rationale, the basic concepts and the reference configurations for the "antenna-based sensors". The review includes real examples and case studies given by the state-of-the-art scientific literature
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