Electromagnetic scattering by arbitrary surfaces modelled by linear triangles and biquadratic quadrangles

One method to solve general three-dimensional electromagnetic problems is the method of moments applied to integral equations. This method approaches the unknown surface currents by basis functions, set up on the interpolated surface of the scatterers. Mostly, one uses roof-top functions as basis functions. Various geometrical interpolation schemes have been proposed like the triangular patch by Rao et al. (1982). In this paper biquadratic functions are used. It compares these two interpolation schemes by means of the RCS of a sphere. Three cases are considered: PEC, dielectric lossy sphere, and the numerically problematic case of a low dielectric contrast.