Distributed equivalent dipole solutions of three-dimensional scattering problems

The authors apply the modal expansion method for calculating the three-dimensional scattering problems of perfectly conducting obstacles, but modify it by superseding the multipole expansion of the field by a distributed multiple dipole expansion on an arbitrary closed surface taken in the interior region. To confirm the numerical tractability of the approach, the calculated results are compared with those obtained previously for problems of scattering from a conducting sphere and cube. The authors´ results are on a smooth curve and show a good agreement with the AMFIE solution in the low-frequency range, but show a growing divergence in the high-frequency range, especially around 4a/ lambda /sub 0/=5, where a spurious MFIE solution can exist.<>