EM-wave scattering by a coastal wedge-a physical optics approximation

The problem of scattering from an impedance wedge has been treated in the past for the cases of plane-wave and line-source illumination. The three-dimensional case of point-source excitation has previously only been handled by means of high-frequency ray techniques. In this paper, scattering of a spherical wave by a coastal wedge is examined through a physical optics approximation. Our approach is based on the Stratton-Chu integral equation and the Sommerfeld solution for the problem of dipole radiation over a conductive half-space. The scattered electric field intensity above the coastal wedge is obtained in the form of multiple integrals over the spatial frequency domain which, far from the wedge, reduce to simple expressions through use of stationary point integration techniques. A correction to the field is made by introducing a fictitious line charge along the edge, which compensates for the field discontinuity across the junction of the two faces of the wedge. Numerical results for typical coastal wedges are presented. Far-field scatter is continuous and finite in all directions, including those along the single-reflection shadow boundaries.