Double reflections in the physical theory of diffraction

integrations generally cannot be performed in closed form, and numerical integrations may be necessary. The analysis becomes nuch more difficult to formulate for general objects. The formulation for finding the double reflected field begins by first determining the physical optics current on the first surface due to the incident tangential magnetic field. The vector potential due to this current can be used to find the fields induced in all space. At another conducting surface, the reflected field is used to determine the physical optics current density due to the first reflection. The vector potential due to this second reflection can be found by a surface integration over the second conducting surface. The reflected fields, which contribute to the total backscatter cross section, can then be found using the far-field approximation. When adding higher order reflections, however, the surface