Generation of field scattered by imperfectly conducting objects from the solution of a perfectly conducting object

Impedance boundary conditions are applied to derive the surface currents induced on an imperfectly conducting object from the surface current of a perfectly conducting object. In the case of highly conducting objects, when the surface impedance is small, the surface electric currents are initially approximated by those of a perfectly conducting object in an integral equation formulation, and then used to compute the surface magnetic currents using the surface impedance. Application of the method to an imperfectly conducting sphere shows the computational errors generally to be low in the resonance region, although they may become unacceptable at very low frequencies for a plane wave or magnetic dipole excitations.