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Modélisation de la propagation des ondes électromagnétiques près du sol : application aux réseaux sans fil

Abstract : Motivated by the development of various applications deploying antennas near an interface, such as military systems (UGS), wireless body area networks (BAN) and environmental monitoring involving ground sensors, this thesis deals with the near-ground wave propagation modelling. First, the results of the geometrical optics are confronted with the approximations provided by Norton and Bannister. This study reveals the cases where geometrical optics does not correctly describe the wave propagation near the surface. For a more comprehensive understanding, Green's functions of this type of propagation, presented as Sommerfeld integrals, are evaluated using the steepest descent technique. This evaluation offers the possibility to extract three important equations for near-ground wave propagation. The first one presents the essential condition under which the link budget can benefit from the ground proximity through the excitation of a diffracted wave component propagating near the interface. The other two equations identify critical distances indicating the beginning and the end of the zone with an improved path loss. All these three equations highlight the role of certain physical parameters, in particular the electromagnetic properties of the ground, the working frequency and the heights of the antennas. This thesis also includes the practical solutions that can be considered to demonstrate the feasibility of improving a wireless link by the proximity of the antennas to the interface. Since floor coating is of major importance, we present preliminary research on the realisation and characterisation of a suitable material for this type of propagation. In a parallel research axis, this thesis also evaluates the accuracy and relevance of a new theoretical formulation for near-ground propagation. The "so-called Schelkunoff" formulation has become a controversial issue in the scientific community
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Submitted on : Monday, May 7, 2018 - 11:48:07 AM
Last modification on : Wednesday, September 28, 2022 - 5:56:58 AM
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  • HAL Id : tel-01787107, version 1

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Maurício Henrique Bezerra Cardoso. Modélisation de la propagation des ondes électromagnétiques près du sol : application aux réseaux sans fil. Electronique. Université Paris-Est, 2017. Français. ⟨NNT : 2017PESC1035⟩. ⟨tel-01787107⟩

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