Modélisation électromagnétique des radômes par des techniques basées sur les faisceaux gaussiens

Abstract

In many configurations, an antenna has to be protected from the outer environment by a radome. In this thesis, we propose to use gaussian beam based techniques to take into account the radome effect on the antenna radiation. These beams are approximate analytical solutions of the propagation equation. They depend on the paraxial approximation (low diverging field assumption).We first develop a new approach to expand an electromagnetic field on a set of elementary beams, overcoming some limitations of the two existing expansions (Multimodal and Gabor). Then, we study the interaction between an incident field and a multilayer dielectric object. So, we develop a shooting and bouncing gaussian beam algorithm which assumes that one incident gaussian beam crossing a dielectric interface gives one reflected and one transmitted gaussian beams. Another original technique is proposed using gaussian beam transmission and reflection coefficients. They provide analytical expressions for the transmitted and reflected fields on a dielectric interface (or on a thin dielectric multilayer) illuminated by a gaussian beam. These two techniques are compared with a conventional plane wave approach on several test cases. The results show their rapidity and accuracy. In order to deal with the problem of aircraft or missiles front-end sharp radomes, we finally explore novel expansions requiring a new kind of beams, called conformal gaussian beams . Some comparisons with simulations performed with an existing industrial software show their efficiency.TOULOUSE3-BU Sciences (315552104) / SudocSudocFranceF