A higher‐order surface boundary condition for a dielectric substrate backed by a nonperfect conductor

A higher‐order surface impedance boundary condition (HOIBC) for a dielectric substrate backed by a nonperfect conductor is presented. The boundary condition is derived first in the spectral two‐dimensional Fourier domain, and later in the space domain. It is shown that in the space domain such a condition is expressed by a dyadic operator acting on the tangential components of the magnetic field. Finally, in order to demonstrate the qualities of the proposed HOIBC, a comparison of the field radiated by a horizontal electric dipole (HED) placed on the considered structure, computed using the exact and the approximated (higher‐order) impedance boundary condition (IBC), has been presented.