Usability Studies on Approximate Corrugation Models in Scattering Analysis

Often an actual scatterer geometry is replaced with a computationally more economical model. For example, if a major part of the scatterer surface is corrugated, one solution is to analyze scattering by replacing the corrugated areas with flat impedance surfaces. But then a question arises: what is actually the error in the scattered field phase and magnitude due to this approximation? In this paper, planewave scattering from partly corrugated structures is studied. The analysis is based on integral equations (IE) and method of moments (MoM). Two-dimensional geometry and fields are assumed. TM_z and TE_z cases are analyzed separately. It is investigated how the magnitude and phase of the scattered TM_z and TE_z fields depend on the used corrugation model: exact-geometry results are compared with the approximate results in a wide frequency band. Also the phases of the TM_z and TE_z fields must be predicted correctly, if studying the polarization state of the scattered field. The paper ends with an example where a corrugated corner reflector is investigated via an exact model and via different approximate models