Comparison of Ray Theory with Exact Theory for Scattering by Open Wave Guides

Abstract

The exact solutions for electromagnetic scattering by a semi-infinite parallel plane wave guide and by a semi-infinite circular pipe are expanded asymptotically for wave guide dimensions large compared to wavelength. Attention is confined to the diffracted field at observation points well away from shadow boundaries and reflection boundaries. The results yield term by term comparisons with the corresponding results derived by means of ray theory. The simple ray method does not yield complete agreement with the asymptotic forms of the exact solutions.