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Modèle large bande de matériaux composites dans la méthode FDTD conforme pour le calcul de la Surface Equivalente Radar

Abstract : Metamaterials are three-dimensional complex structures often periodics. They have electromagnetic properties that are not found in conventional materials. These can be applied to a target to reduce its Radar Cross Section (RCS) and thus make it more furtive. The Finite Difference Time Domain (FDTD) method is a good candidate to simulate the periodic metamaterial and the target covered with this material, due to its efficiency and wideband characteristic. Since the dimension of the metamaterial is very small compared to the target one, it is necessary to solve a multi-scale problem which is difficult to deal with a full wave method. This thesis therefore proposes to apply the metamaterial as an equivalent boundary condition via the Leontovich formula. The model takes into account the polarization and the incidence of the plane wave. To establish the surface impedance model, a pattern of the metamaterial is modelled with periodic boundary conditions. The Spectral FDTD scheme is chosen for several reasons. On the one hand, existing models can be easily adapted to this method. On the other hand, the CFL condition is not restrictive and is the one given by the standard Yee scheme. In addition, this thesis proposes to combined the scheme with the TD-VFz signal extrapolation technique to improve the spectral response accuracy. This original combined scheme allows the surface impedance computation of complex absorbers from the literature. Finally, a conformal FDTD modelling of the target is proposed to take into account its curvilinear geometry which is no longer approximated by a staircase mesh. This approach is validated for both an inclined plate and a desaxed cube receiving a metasurface.
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https://hal.archives-ouvertes.fr/tel-03820106
Contributor : ABES STAR :  Contact
Submitted on : Thursday, November 10, 2022 - 4:52:57 PM
Last modification on : Friday, November 11, 2022 - 3:29:28 AM

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2022LIMO0066.pdf
Version validated by the jury (STAR)

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  • HAL Id : tel-03820106, version 2

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CEA | UNILIM | CNRS | XLIM | STAR | DAM

Citation

Samuel Gaucher. Modèle large bande de matériaux composites dans la méthode FDTD conforme pour le calcul de la Surface Equivalente Radar. Matériaux composites et construction. Université de Limoges, 2022. Français. ⟨NNT : 2022LIMO0066⟩. ⟨tel-03820106v2⟩

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