Higher order impedance boundary conditions for anisotropic and nonreciprocal coatings

The topic of approximate impedance boundary conditions is examined using a spectral-domain approach. New forms for general approximate impedance boundary conditions with broader applicability than the SIBC, TIBC or GIBC (standard, tensor, or generalized impedance boundary condition) are derived. Using the spectral-domain approach, higher-order boundary conditions for coatings which cannot be handled by the existing approximate impedance boundary conditions can be addressed. They include complicated coatings containing anisotropic and nonreciprocal materials as well as those with more complicated constitutive relations such as chiral media.<>