Fabrice Auzanneau

Passive artificial molecule realizations of dielectric materials

The design of dielectric materials with artificial molecules formed by electrically small dipole antennas loaded with passive electrical circuit elements is considered. Variations in the antenna loads lead to known and generalizations of known dielectric material models. These artificial dielectrics are characterized in terms of their equivalent susceptibilities and polarization vectors both in the frequency and time domains. With suitable choices in the antenna loads one can design the loss and dispersion properties of the resultant materials.

Artificial molecule realization of a magnetic wall

The design of magnetic materials can be achieved with artificial magnetic molecules formed by electrically small loop antennas loaded with passive electrical circuit elements. A time derivative Lorentz material response is achieved with a series resistor and capacitor load. It is shown that the parameters of this magnetic molecule can be selected to yield a time derivative Lorentz material that acts as a highly conducting magnetic wall.

Microwave signal rectification using artificial composite materials composed of diode-loaded electrically small dipole antennas

The electromagnetic properties of composite materials composed of dipole or loop antennas (also called molecules) loaded with different linear passive electronic circuits are summarized. These molecules are extended to those molecules whose loads contain some basic nonlinear elements. Several examples are discussed. The simplest nonlinear load is the clamping circuit: a diode and a resistor are connected in series to an electrically small dipole antenna. This is generalized to a more complicated molecule based on a diode bridge. Numerical results generated with a finite-difference time-domain (FDTD) simulator demonstrate how an incident narrow-bandwidth pulse interacts with these materials and can be transformed into a baseband, rectified signal, or a signal containing selected harmonics of the fundamental frequency. Potential applications of these artificial material-based signal convertors include target identification and signal modulation.

Artificial composite materials consisting of nonlinearly loaded electrically small antennas: operational-amplifier-based circuits with applications to smart skins

Several new artificial nonlinear composite materials are introduced in this paper. They consist of electric molecules constructed with nonlinearly loaded electrically small dipole antennas. Their behaviors are studied with an augmented finite-difference time-domain (FDTD) simulator. The loads are based upon the use of multiple diodes and ideal operational amplifiers. The resulting composite materials are shown to have nonlinear electromagnetic properties including the ability to create any desired set of harmonics and subharmonics from an input wave having a single fixed frequency. Curve shaping circuits are introduced, simulated, and used to design materials that produce output signals of specified forms. Because the operating points of these curve shapers are adjustable, they could be modified in real time. The resulting smart materials could be designed in the microwave region to produce any specified response to a recognized input signal.

Détection et localisation de défauts dans des réseaux filaires de topologie complexe

RésuméLa réflectométrie est une méthode couramment utilisée pour déterminer l’état électrique de câbles et de lignes. Cette méthode fournit des informations pour la détection, la localisation et la caractérisation de défauts électriques. Le CEA LIST travaille sur l’implémentation de cette méthode pour le diagnostic de réseaux filaires de topologie complexe, pour des applications embarquées ou de diagnostic en ligne. Les domaines d’application concernent les télécommunications, l’automobile et les transports, la distribution d’énergie, etc.Cet article présente un nouveau modèle théorique pour la simulation rapide et précise de signaux de réflectométrie appliquée à tout type de réseau filaire. Basée sur la théorie de la propagation RF, ce modèle fournit des formules explicites pour simuler la réflectométrie dans les domaines temporel (TDR) et fréquentiel (FDR), explique les phénomènes et permet une meilleure compréhension de ces signaux en rapport avec la topologie du réseau.AbstractReflectometry is a well known method widely used to monitor the health of lines and wired networks. This method provides information for the detection, localization and characterization of electrical defects in networks. CEA LIST works on the development and the application of this method for the diagnosis of wired networks of complex topology, targeting embedded systems. Application domains range from telecommunication to automotive and transport, energy distribution, etc.This paper presents a new theoretical model for the precise numerical simulation of reflectometry signals applied to any kind of wired network. Based on standard microwave propagation theory, this model provides simple explicit formulas for both time domain (TDR) and frequency domain (FDR) reflectometry, and is helpful to better understand and explain measurement results in relation with the network’s topology.

EXPLICIT MATRIX FORMULATION FOR THE ANALYSIS OF SYNTHETIC LINEARLY AND NON LINEARLY LOADED MATERIALS IN FDTD

We present a new matrix differential equation formulation for the analysis of the response of linearly and non linearly loaded molecules to an incoming electromagnetic wave. The molecule is defined as an electrically small dipole or loop antenna connected to an electronic circuit called the load. Because we have a Maxwell FDTD code, we use a finite difference scheme to solve the differential equations, which greatly simplifies the problem. If the load is linear, a simple linear system of update equations can easily be derived from the system of differential equations describing the behavior of the load circuit. This approach leads to a natural choice for the intermediate unknowns in the use of the Auxiliary Differential Equation method, and gives a fully explicit matricial update equation. If the load contains one or more non linear devices, this method can be generalized and leads to the resolution of a system of non linear update equations with a simple Newton Raphson or Runge Kutta algorithm. Several n...

Champ à la surface ďun objet axisymétrique conducteur au voisinage ďun point focal de rayons rampants

RésuméOn considère un objet axisymétrique illuminé par une onde plane en incidence axiale. Les champs de surface dans la zone ďombre sont dus aux ondes rampantes et sont donnés, loin de ľaxe de symétrie, par les formules de la théorie géométrique de la diffraction. Le point sur ľaxe de symétrie est un foyer pour les ondes rampantes et les formules précédentes y prédisent un résultat infini. On détermine, à ľaide ďune méthode de développement asymptotique, une solution pour les champs au voisinage du foyer. Cette solution tend vers les résultats de la tgd loin du foyer et reste bornée au foyer. La comparaison à des résultats obtenus par équation intégrale sur des sphéroïdes allongés ou aplatis est satisfaisante.AbstractWe consider an axisymmetric obstacle illuminated by a plane wave propagating along the axis of symmetry. The surface fields in the shadow zone are given, far from the axis, by the geometrical theory of diffraction formulas. The point on the axis is a creeping wave focus and the gtd formulas predict an infinite result at this point. We compute, by using an asymptotic expansion method, a solution for the fields in the vicinity of the focus. This solution merges with gtd results far from the focus and remains bounded at the focus. Comparison with method of moment results on prolate and oblate spheroids show a good agreement.

Chaos Time Domain Reflectometry for Online Defect Detection in Noisy Wired Networks

In many application domains, wire faults can have dramatic consequences. Live wire diagnosis is often required to ensure permanent monitoring of the health of embedded cables. A novel reflectometry-based method for online wire diagnosis is presented. Chaos time domain reflectometry (CTDR) takes benefit of the properties of chaotic signals and shows very good potential for the diagnosis of live wires (i.e., during their operational usage) and complex topology networks. In particular, CTDR shows high performances in very noisy environments: the detection and the location of hard defects are possible even in the case of negative signal to noise ratio and if several reflectometers inject their signals in the cable. This enables using CTDR for the distributed diagnosis of live complex topology networks of lengths up to several tens of meters. CTDRs defect detection capacity is shown and experimentally verified: increasing the length of the probe signal lowers the noise level. A noise robustness analysis provides a means to choose the signals parameters necessary to ensure specified detection performances.