Pierre Lemaitre-Auger

Tunable Near-Field Focused Circular Phase-Array Antenna for 5.8-GHz RFID Applications

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.

A Tapered CRLH Interdigital/Stub Leaky-Wave Antenna With Minimized Sidelobe Levels

A nonuniform (NU) tapered composite right/left-handed (CRLH) leaky-wave antenna (LWA) with minimized sidelobe level (SLL) is proposed. The design of this antenna is performed using an automated cosimulation approach based on a genetic algorithm optimization. Fair agreement is found between the full-wave and the experimental results. The experimental results show an 8-dB SLL reduction compared to a uniform CRLH LWA with the same gain in a 12-unit-cell structure.

Toward RCS Magnitude Level Coding for Chipless RFID

Hybrid coding techniques have been proposed recently to improve the coding capacity of chipless RF identification (RFID) tag. This paper examines the possibility to code information thanks to the magnitude level of the radar cross section (RCS) in addition to the more classical technique of frequency position (FP). Single-layer tags based on C-folded dipoles are designed to have different magnitude levels. A magnitude span of up to 15.2 dB is obtained for coupled resonators. A magnitude resolution of 3.5 dB is evaluated for practical applications based on the measurement of the realized tags in different configurations. The problem of tags applied to an unknown object is considered and a compensation technique is proposed for an object similar to a thin dielectric plate.

Near field focusing circular microstrip antenna array for RFID applications

A circular microstrip array with beam focused for RFID applications was presented. An analogy with the optical lens and optical diffraction was made to describe the behaviour of this system. The circular configuration of the array requires less phase shift and exhibite smaller side lobe level compare to a square array. The measurement result shows a good agreement with simulation and theory. This system is a good way to increase the efficiency of RFID communication without useless power. This solution could also be used to develop RFID devices for the localization problematic. The next step of this work is to design a system with an adjustable focus length.

RFID tags localization along an axis using a tunable near-field focused circular-phase array antenna

A novel concept for RFID tag localization using a tunable near-field focused circular-phase array antenna working at 5.8 GHz is presented. It serves as the reader antenna and focuses the power into a small region, in the tag vicinity. By scanning the focal spot along one axis and monitoring the differential scattered power by a tag, its position along the axis is easily computed with good accuracy. This simple localization scheme is well adapted for specific localization scheme, for example for objects placed over a conveyor belt.

Improvement of a glass integrated optical displacement sensor interferometer using acousto-optic effect

Optical interferometer displacement sensors are well known for their high resolution, up to 10−7 m in a stabilized environment, over a wide measuring range which can reach several metres. Moreover, the measurements are carried out without any mechanical contact with the target object. Two optical outputs are however needed to determine the displacement sign. A glass integrated sensor with only one optical output that still measures the displacement sign is proposed here. It is derived from a Michelson interferometer but is realized by ion exchange on a glass substrate. A piezoelectric element placed over the reference arm produces a longitudinal acoustic wave that creates a small phase modulation in the reference light beam at a high frequency (1.28 MHz). A small modulation of the output signal is thus produced. The direction determination is based on the comparison between the phases of the excitation acoustic signal and of the high frequency part of the sensors output signal after proper signal processing. A theoretical and an experimental demonstration of that principle are presented. A precision of 158 nm was obtained with simple numerical signal processing.

Circular antenna array for microwave Bessel beam generation

A circular antenna array (CAA) is proposed and demonstrated for the generation of optimal pseudo-Bessel beams at millimeter-wave frequencies. Numerical simulations show that a 91-element array produces a Bessel beam of a 7λ main lobe width over a distance of 180λ. Based on this report, it is suggested that Bessel beams may provide a unique solution to millimeter-wave quasi-optical systems by providing highly focused beams with small-sized antennas.

Bending and crumpling effects on a wearable planar monopole antenna

A Coplanar WaveGuide (CPW) monopole antenna designed to operate at the frequency (fr) of 2.05 GHz and intended to be put over a fabric is tested with respect to substrate deformations. In absence of deformations, the antenna bandwidth is 18.8% and its reflection coefficient is -44 dB. Deformations tested are bending in the H or the E-plane, crumpling and a combined situation. Results show that bending effect will not greatly affect the antenna in realistic situations (i.e. bending radius bigger or equal to 5 cm). Crumpling effect is more important and should be prevented.

Generalized Array Factor Approach to the Assessment of Discrete Tapered Nonuniform Leaky-Wave Antenna

A generalization of the array factor approach of a nonuniform leaky-wave antenna (LWA) is proposed for the modeling of discrete tapered LWAs. The demonstration is based on the Fourier transform of the illumination amplitude of an LWA and is thus quite general. This analysis approach can be helpful for design. When it is used in combination with classical taperization techniques, it provides an easy and powerful conception tool. The validity of the method is demonstrated with the Holey and the Honey LWAs. Taylor and cosine distributions were simulated and sidelobe level reduction up to -40 dB were obtained. A Holey antenna designed to work at 1.7 GHz with a cosine distribution was realized. Its radiation pattern was measured and it shows an acceptable agreement with theory and numerical simulations.

Chipless identification applied to human body

We report in this paper the study of the identification of persons using a Radio Frequency IDentification (RFID) chipless tag. Obtained results show that a robust identification is possible due to the capability of the tag to generate a cross polarization that is used for the identification. Simulations and measurements of a chipless tag placed on a body have been made. By this way, the tag could be easily designed to be an integral part of a clothing.