A new multipole approach for scattering problems

The analysis of electromagnetic scattering by canonical structures has served as a basis for the development of asymptotic methods such as the geometrical theory of diffraction (GTD). The paper deals with a new approach which allows the scattered far field to be systematically derived and evaluated, especially for a class of semi-infinite geometries, including the circular cone, the elliptic cone, and the plane angular sector. Exemplarily, the method is applied to calculate the GTD diffraction coefficient for the half-plane edge where the closed-form result was given by J.B. Keller (see J. Opt. Soc. America, vol.52, p.116-30, 1962). The obtained result compares excellently to Keller´s solution. The method can be generalized to more complicated geometries where no closed results may be achievable.