Electromagnetic Scattering from Infinite Strip Grating with Inhomogeneous Material Coating using a Combined Surface and Volume Integral Equation Formulation

A combined-field integral equation is developed to analyse electromagnetic scattering from planar flat strip and infinite periodically located strip grating with homogeneous and/or inhomogeneous material coating. The equivalence principle is used to replace all conducting strips by equivalent surface electric currents and all dielectric coatings by equivalent volume electric and magnetic polarization currents. Utilizing the respective boundary conditions, an operator equation containing both volume and surface currents is constructed in the spectral domain and solved by the generalized BiConjugate Gradient (BiCG)-FFT method. Numerical results are presented for various geometries for both (transverse electric and transverse magnetic ) polarizations as well.