## Section: New Results

### Scattering from Rough Unbounded Penetrable Layers

Participants : Houssem Haddar, Armin Lechleiter.

Scattering of electromagnetic waves from the surface of ground are often modelled by a time-harmonic scattering problem involving unbounded scattering objects. We are interested in theoretical and numerical studies of this type of problems via variational formulations. In that perspective we considered the scattering of time-harmonic electromagnetic waves from a metallic plate coated with a dielectric layer. This problem occurs for instance when monochromatic light propagates through photonic assemblies mounted on a plate. We first established a variational framework using the DtN map for Maxwell equation in half space. As opposed to the scalar case, the real part of this operator does not have a fix sign, which induces difficulties is establishing existence of solutions. The latter is done using an appropriate limiting absorption principle combined with a priori estimates derived from Rellich type identities. Our analysis only apply to small perturbation of stratified parallel layers [39] . We are now interested in cases where the perfect conductor has a rough surface and also in widening the range of admissible material configurations.