HIGHER-ORDER IMPEDANCE BOUNDARY-CONDITIONS REVISITED - APPLICATION TOCHIRAL COATINGS

In this paper, a novel spectral domain method for obtaining higher ord er impedance boundary conditions for the problem of electromagnetic sc attering from complex coatings is described. The method is then applie d to the specific case of chiral coatings on conductors. The present m ethod for obtaining the boundary conditions is quite general, and is a pplicable to coatings with arbitrary constitutive relations, including anisotropic coatings, such as dielectric layers with tensor permittiv ity, and non-reciprocal coatings, such as magnetically biased ferrites . Multiple layers may also be handled in a systematic manner. Although the examples presented focus on boundary conditions containing tangen tial derivatives no higher than second order, an extension to higher o rder conditions is also straight forward. The standard impedance bound ary condition (SIBC), tensor impedance boundary condition (TIBC), and the generalized impedance boundary conditions (GIBC), are contained as special cases of the general method described in this paper. It is al so shown how the general method presented allows the effects of curvat ure to be included in the boundary condition. The examples presented i nclude a number of planar chiral layers and chiral coated circular cyl inders, and illustrate the accuracy of the proposed boundary condition s.