A flexible and dual-frequency microstrip applicator for microwave local hyperthermia is described. It is designed on conformal liquid crystal polymer (LCP) substrate and operating at ISM (Industrial, ...Scientific and Medical) frequencies of 915 MHz and 2.45 GHz. To conform the body’s curvature, the applicator is bent on a cylindrical body. 3D electromagnetic CST Microwave Studio was used to determine the performance of the applicator and to evaluate the specific absorption rate (SAR) distribution in cylindrical human body phantom. The results obtained show that the antenna can be used in curved situation for uniform and superficial treatment.
Design of Antennas for UHF RFID Tags Perret, Etienne; Tedjini, Smail; Nair, Raji Sasidharan
Proceedings of the IEEE,
07/2012, Letnik:
100, Številka:
7
Journal Article
Recenzirano
This paper is mainly dedicated to the design of radio-frequency identification (RFID) tags, particularly the antennas that allow the tag to be fed, communicate, and exchange data with the reader. ...Good performance tags require optimized antenna that take into account numerous constraints as well as the environment of the application under consideration. Both conventional tags and robust tags are discussed. This paper also discusses how to transform a tag into an RFID sensor.
An RFID-compatible focused circular phase-array antenna working at 5.8 GHz is proposed, which is theoretically analyzed and experimentally demonstrated. It consists of 24 half-wavelength dipole ...antennas placed on three circles. Using only two phase-shifters, a tunable focal spot in the range of 0.4-1 m (10λ) is obtained. The antenna system is analyzed using the Huygens-Fresnel theory, which is compared to the experimental results. At a focal distance of 0.9 m, the measured beam width and focal depth are given by 0.75λ and 5λ, respectively, which are in agreement with the calculated results.
Billions of Radio-Frequency Identification (RFID) passive tags are produced yearly to identify goods remotely. New research and business applications are continuously arising, including recently ...localization and sensing to monitor earth surface processes. Indeed, passive tags can cost 10 to 100 times less than wireless sensors networks and require little maintenance, facilitating years-long monitoring with ten's to thousands of tags. This study reviews the existing and potential applications of RFID in geosciences. The most mature application today is the study of coarse sediment transport in rivers or coastal environments, using tags placed into pebbles. More recently, tag localization was used to monitor landslide displacement, with a centimetric accuracy. Sensing tags were used to detect a displacement threshold on unstable rocks, to monitor the soil moisture or temperature, and to monitor the snowpack temperature and snow water equivalent. RFID sensors, available today, could monitor other parameters, such as the vibration of structures, the tilt of unstable boulders, the strain of a material, or the salinity of water. Key challenges for using RFID monitoring more broadly in geosciences include the use of ground and aerial vehicles to collect data or localize tags, the increase in reading range and duration, the ability to use tags placed under ground, snow, water or vegetation, and the optimization of economical and environmental cost. As a pattern, passive RFID could fill a gap between wireless sensor networks and manual measurements, to collect data efficiently over large areas, during several years, at high spatial density and moderate cost.
Third Harmonic Exploitation in Passive UHF RFID Andiia Vera, Gianfranco; Duroc, Yvan; Tedjini, Smail
IEEE transactions on microwave theory and techniques,
09/2015, Letnik:
63, Številka:
9
Journal Article
Recenzirano
This paper unfolds the recent concept of using harmonic signals generated by the nonlinear behavior of traditional passive UHF RF identification (RFID) chips. The harmonics generation of passive RFID ...chips is analyzed to highlight the influences of the matching network and the tag antenna. The proposed study relies on a theoretical model that explains the role in the harmonic production of different elements constituting the tag. The model also shows how to achieve a second communication channel exploiting the third harmonic frequency in addition to the fundamental frequency channel. Specifications and methodology are explained in a harmonic communication scenario. The regulations, harmonic RFID reader considerations, harmonic tag guidelines design, and metrics for its evaluation are discussed. In compliance with the standard regulations EPC Class-1 Gen2 RFID, a design example is presented. The performance of the solution is illustrated from simulation and measurements. The prototype example operates simultaneously at fundamental and third harmonic frequencies with a read range greater than 4.5 m.
RFID Test Platform: Nonlinear Characterization Andia Vera, Gianfranco; Duroc, Yvan; Tedjini, Smail
IEEE transactions on instrumentation and measurement,
09/2014, Letnik:
63, Številka:
9
Journal Article
Recenzirano
This paper presents a complete radio frequency identification (RFID) test platform to characterize the nonlinear effects produced by passive ultra-high frequency (UHF) RFID chips. In full operation ...mode, automated measurements of activation power, harmonic response level, and impedances are performed in a wide frequency range up to the fourth harmonic. The characterization method, platform composition, and operation are explained through real measurements on UHF Class-1 Generation-2 chips. A harmonic treatment is presented thanks to the joint use of an RFID tester and impedance tuners, and the effect of the antenna-chip impedance matching on the harmonic responses is compared before and after treatment. To the best of our knowledge, no similar platform has been presented in the literature.
This letter proposes, for the first time, a wireless passive chipless RFID tag for identification and humidity sensing applications. The proposed sensor tag, based on time domain, consists of ...cascaded group of transmission-line sections (C-sections) coupled at alternative ends capable of producing group delay peaks at a particular frequency. C-sections allow producing a unique ID for a tag. Sensing is achieved by depositing silicon nanowires on the strips of the C-sections group. Silicon nanowires are very sensitive to environmental humidity variation, which in turn changes the radar cross section (RCS), phase, and group delay of the tag. This feature is utilized for humidity sensor applications. The proposed sensor tag is experimentally verified. An RCS change of 30 dB and group delay variation of nearly 22.3 ns was observed near the fundamental frequency over a bandwidth of 40 MHz for a relative humidity variation of 60.2%-88%. Measurements were performed in a real environment. The obtained results confirm the very good potential of nanowires in humidity sensor applications.
A simple solution to efficient pressure measurement in sports balls using a force sensitive resistance sensor connected to an ultra high frequencies (UHF) radio frequency identification (RFID) tag is ...presented. The proposed solution has the advantage of increasing the pressure range measurement without changing the configuration of the employed RFID chip. It also offers a small and compact sensor structure due to miniaturised antenna design. The designed antenna is placed between the ball inner and outer layers. Prototypes were fabricated on a flexible substrate to make their integration easy into a sport ball. This smart tag concept was fully validated through measurements on different types of sports balls, and the results successfully compared to data from electronic ball pressure gauge.
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