Scattering by resistive plates

The problem of electromagnetic scattering by resistive plates has been solved numerically using two coupled E-field integral equations and the method of moments. The Stratton-Chu representation for the electromagnetic field has been shown to be applicable to this type of problem and integral equations are derived from this representation. The numerical procedure developed guarantees the continuity of the potentials on the plate, a property which is shown to be essential for the convergence of the solution. The solution was tested by comparison with measured RCS data of resistive and perfectly conducting plates and the agreement for plates of about one square wavelength in area was within 1 to 2 dB for all angles of incidence. The low frequency behavior of a resistive plate has been compared to that of a perfectly conducting one based on the leading terms of the Rayleigh series. For a resistive plate the electric dipole moment is the same as for a perfectly conducting one but the magnetic dipole moment is zero. The transition to perfect conductivity is therefore discontinuous at low frequencies. The effect of the resistivity appears in the quadrupole term, and this can be expressed in terms of potentials similar to those required for the dipole contribution. The dipole moments for plates of several shapes have been computed by solving the integral equations for the static potentials.