Scattering by a material filled groove using cavity mode impedances

Scattering by a 2-D trough in an infinite conducting ground plane may be formulated using integral equations, impedance boundary conditions, and mode coupling to cylindrical harmonics. An efficient technique requiring no matrix inversions is developed here for the case of a rectangular groove containing homogeneous isotropic material defined by complex /spl epsiv//sub r/ and /spl mu//sub r/. Although the formulation is based upon a large aperture approximation, it has been found to provide accurate results for apertures as small as 1.25/spl lambda//sub 0/.<>