On the FEM Modal Approach for a Reverberation Chamber Analysis

We review the difficulties linked to the modal approach when modeling a reverberation chamber by the finite element method (FEM). The numerical challenge is due to the large-scale problem involved by the overdimensioned cavity. Moreover, the field singularity on the stirrer has to be captured by the FEM. First, the following issues are discussed: existence of null-frequency solutions, convergence rate for $h$ and $p$ adaption, and formulation type in ${\bf E}$ or ${\bf H}$ field. The modal analysis is then compared to the classical harmonic one. Focus is put on the field singularity at the source point.