The Modified Surface-Normal Vectors in the Physical Optics

Simple equivalent surface currents perturbed from the physical optics (PO) are proposed, which predict accurate scattering fields without using a special knowledge about the high frequency asymptotic theories such as the geometrical theory of diffraction (GTD). A novel and empirical concept named ldquomodified surface-normal vectorsrdquo is introduced in the classical definition of the PO current, which is defined in a way that the reflection law is satisfied at each point of interest in the integration region. This empirical and geometrical replacement of the surface-normal vectors drastically enhances the accuracy of the PO to a level of the GTD.