On Characteristic Modes in the Presence of a Grounded Dielectric Slab

In this work, the characteristic modes of a perfectly electrically conducting scatterer in the presence of a lossless grounded dielectric slab are investigated. The orthogonality properties of the far fields of the characteristic modes are discussed in terms of space wave and surface wave far fields. Then, the resonance behavior of the characteristic modes is examined under variation of dielectric permittivity, dielectric slab thickness and frequency. As it turns out, the far field orthogonality of lossless systems still holds true overall, but it must be distinguished between space wave and surface wave fields. Also, the resonance behavior can be systematically explained using knowledge from patch antennas and geometrical optics.