A Numerical Technique for Computing the Values of Plane Wave Scattering Coefficients of a General Scatterer

The results of a numerical technique for computing the plane wave scattering coefficients of a general scatterer are presented. The technique is tailored herein to the case where the scatterer is a general slab and the technique is implemented with the FDTD method of the scattered field formulation. Since the technique relies on the use of a Maxwellian beam of dominant polarization as the excitation within the FDTD simulation, this paper presents also an improved scheme for synthesizing such a beam. Window averaging is also presented as a new scheme for mitigating the effects of aperture truncation. Validation of the technique revealed that the use of a non-Maxwellian Gaussian beam of uniform polarization produced erroneous values of the plane wave scattering coefficients. When used with a Maxwellian beam excitation, however, the technique showed to be trustworthy, stable and accurate, even for lossy media. Convergence test results revealed that the accuracy of the values of plane wave scattering coefficients decreased much faster as the conductivity of the medium increased than what would be expected from numerical anisotropy. Finally, poor accuracy results are reported when the scattered field illuminates strongly the edges or corners of the integration box around a finite-size slab.