Approximating the scattering by a material-filled 2-D trough in an infinite plane using the impedance boundary condition

An application of the impedance boundary condition to 2-D trough scatterers is described in which the approximate field solutions are obtained at a much reduced computational cost compared with more exact numerical approaches. The geometries investigated have appreciable subsurface interactions that must be accounted for in the surface impedance. After a brief canonical study of the coated circular cylinder, the filled 2-D trough in a ground plane (which can be used as a model for an antenna-cavity mount) is analyzed and compared with a more exact numerical approach. The results of a parametric study of this geometry demonstrate that excellent far-field agreement is obtained when the material and structure satisfy only the requirements for the traditional impedance boundary condition. This model is also shown to provide a very good simulation for 2-D troughs with slanted sidewalls which produce inhomogeneous equivalent surface impedance representations