No abstract

[1] Electromagnetic diffraction by a dielectric wedge was analyzed using the method of hidden rays. After ordinary ray-tracing is terminated in the physical region the usual principle of geometrical optics is also applied to trace the hidden rays in the complementary region, in which original media of background and dielectric are exchanged for each other. The diffraction coefficients are constructed by finite series of cotangent functions, which have one-to-one correspondence with not only ordinary rays in the physical region but also hidden rays in the complementary region. The angular period of the cotangent functions is adjusted to satisfy the edge condition at wedge tip. The accuracy of the constructed diffraction coefficients was checked by showing how closely the null-field condition is satisfied in the complementary region.

The diffraction problem is treated for the incidence of an E-polarized plane wave on both interfaces of an obtuse-angled dielectric wedge. Based on the dual integral equation, the total field is obtained by sum of the physical optics solution and the edge-diffracted correction term. Calculated diffraction coefficients and field patterns are plotted in figures for wedge angle 120", incident angles 60" and 70", and relative dielectric constants 2 and 10. It is shown that the Neumann expansion to the nonuniform currents provides a more accurate correction to the physical optics currents than the multipole expansion as the angle of dielectric wedge increases.