Analysis of electromagnetic scattering by artificially soft discs

An analysis of the electromagnetic behaviour of corrugated artificially soft discs, illuminated by a vertical dipole, was carried out by using both numerical and asymptotic methods. The finite-difference time-domain method was used to find near-field distributions. This allows the consistency of the artificially soft model to be tested; furthermore, the near-field data are used to find the radiation pattern by using near-to-far-field transformations. The direct scattering in the far zone was also obtained by using edge integration of incremental diffraction coefficients; these are derived by applying the localisation process of the incremental theory of diffraction to a wedge with perfectly soft boundary conditions on one face and perfectly electric boundary conditions on the other. The effect of the corrugations is analysed in the far-field limit by comparison with a perfectly conducting disc.