We review the difficulties of a modal approach when modeling a Reverberation Chamber (RC) by the Finite Element Method (FEM). The numerical challenge is due to the large scale problem involved by the over-dimensioned cavity. Moreover, the field singularity on the stirrer has to be captured by the FEM. First the following issues are discussed: existence of nullfrequency solutions, convergence rate for h and p adaption, and formulation type in E or H field. Then the modal analysis is compared to the classical harmonic one. A focus is put on the field singularity at the source point.
International audienceWave chaos theory is used to study a modeled reverberation chamber (RC). The first 200 modes of an RC at a given stirrer position are determined by the finite element method, and the Weyl formula is checked for various RC geometries, from integrable to chaotic. The eigenfrequency spacing distribution varies according to the degree of ray chaos in the RC related to its geometry. The eigenmode distributions are also analyzed and compared to the theoretical Gaussian distribution: close to the lower useable frequency, the modes of the studied chaotic RC fairly respect this asymptotic property. A general result of chaotic systems is illustrated: when perturbed by the stirrer rotation, the resonant frequencies of an RC avoid crossing. This means that the frequency sweeps tend to vanish at high frequency
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