On the modeling of thin sheets and coatings in the time-domain finite-element method

The ability to model features that are small relative to the cell size is often important in electromagnetic simulations. In this paper the focus is on modeling of thin material sheets and coatings in the unite-element time-domain method. The proposed method is based on degenerated prism elements, so-called shell elements. For a dielectric sheet the thickness is assumed small compared to the wavelength for all frequencies of interest. An important characteristic of the method is that it takes the discontinuity of the normal electric field component at a dielectric interface into account. The accuracy of the method is demonstrated for a couple of scattering cases.