Diffraction pattern functions of an E-polarized scattering by a wedge composed of perfectly conducting metal and lossless dielectric with arbitrary permittivity are analyzed by applying an improved physical optics approximation and its correction. The correction terms are expressed into a complete expansion of the Neumann's series, of which coefficients are calculated numerically to satisfy the null-field condition in the complementary region.

The H-polarized diffraction by a wedge consisting of perfect conductor and lossless dielectric is investigated by employing the dual integral equations. Its physical optics diffraction coefficients are expressed in a finite series of cotangent functions weighted by the Fresnel reflection coefficients. A correction rule is extracted from the difference between the diffraction coefficients of the physical optics field and those of the exact solution to a perfectly conducting wedge. The angular period of the cotangent functions is changed to satisfy the edge condition at the tip of the wedge, and the poles of the cotangent functions are relocated to cancel out the incident field in the artificially complementary region. Numerical results assure that the presented correction is highly effective for reducing the error posed in the physical optics solution.