Virtual rays for diffraction coefficients of composite wedge

The penetrable wedge is one of the canonical structures for which, until now, an exact solution has not been available. Some heuristic diffraction coefficients of penetrable wedges were constructed by modifying the exact diffraction coefficients of the corresponding perfectly conducting wedge (Booysen, A.J. and Pistorius, C.W.I., 1999). Those heuristic solutions provided acceptably accurate results in some limited cases of penetrable wedge geometries, but their diffraction coefficients could not satisfy the edge condition at the tip of the composite wedge. The paper considers an E-polarized plane wave incident on a composite wedge consisting of perfect conductor and lossless dielectric. A new method is suggested to solve diffraction by a composite wedge. The basic concept of the method is inspired from investigating the relation between geometrical rays and the corresponding diffraction coefficients. The concept uses ray tracing of actual rays in the physical region and virtual rays in the complementary region.