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Outils de synthèse pour les réseaux réflecteurs exploitant la cellule Phoenix et les réseaux de neurones

Abstract : In collaboration with Thales Alenia Space and the French Space Agency (CNES), this PHD takes part in a very active international context on a new antenna: the reflectarrays (RA).Combining the advantages of conventional reflectors and those of networks, RA could eventually replace the currently used shaped reflectors. They consist of a primary source placed in front of a network of cells controlling the properties of the reflected electromagnetic field. Although many studies already focus on the characterization of cells, one of the issues is to carefully select them to achieve the final antenna: this is the synthesis step.An overview of different synthesis methods revealed the complexity to quickly obtain good performance simultaneously on the co- and cross-polarizations, for a wide frequency band and for the realization of shaped radiation pattern. The Phoenix cell is selected in this work for its good properties since it provides the entire phase range following a continuous cycle of geometries.Because one of the constraints in the design of RA is to maintain continuous geometry variations between two juxtaposed cells on the layout, a spherical representation tool made it possible to classify all the studied cells. It judiciously lists all the cells on a continuous, closed and periodic surface.A new step is reached with the design of behavioral models using Artificial Neural Networks (ANN). These models enable to a fast electromagnetic characterization of cells in terms of phase and amplitude of the direct and cross coefficients of the reflection matrix.The originality of the synthesis algorithm proposed in this work is the combined use of the spherical representation and a rapid cell characterization by ANN. A min / max optimization tool is used to improve the overall performance of the RA panel. It is then applied to a concrete case as part of a telecommunication mission.
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https://tel.archives-ouvertes.fr/tel-01805096
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Submitted on : Friday, June 1, 2018 - 2:09:07 PM
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  • HAL Id : tel-01805096, version 1

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Vincent Richard. Outils de synthèse pour les réseaux réflecteurs exploitant la cellule Phoenix et les réseaux de neurones. Electromagnétisme. INSA de Rennes, 2018. Français. ⟨NNT : 2018ISAR0004⟩. ⟨tel-01805096⟩

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