Computation of Scattering by DB Objects With Surface Integral Equation Method

Electromagnetic scattering by objects with a DB boundary condition (normal components of the electric and magnetic flux densities D and B vanish at the boundary surface) is investigated. Scattering of arbitrary-shaped three-dimensional objects is analyzed with the surface integral equation method. A significant difference compared to the more conventional boundary conditions is that the uniqueness of the solution to the scattering problem with DB boundary depends on the connectivity of the object. For a simply connected object the solution is unique but for a multiply connected object some additional conditions are required. It appears that these additional conditions are satisfied if divergence-free basis functions are used to expand the unknown surface current densities. The developed method is applied to calculate polarizabilities, scattering efficiencies, and radar cross sections (RCS) of the DB sphere and cube, and the results are compared with those of the PEC cube and sphere.