Three-dimensional diffraction by infinite conducting and dielectric wedges using a generalized total-field/scattered-field FDTD formulation

We extend the generalized total-field/scattered-field formulation of the finite-difference time-domain method to permit efficient computational modeling of three-dimensional (3-D) diffraction by infinite conducting and dielectric wedges. This new method allows: 1) sourcing a numerical plane wave having an arbitrary incident angle traveling into, or originating from, a perfectly matched layer absorbing boundary and 2) terminating the infinite wedge inside the perfectly matched layer with negligible reflection. We validate the new method by comparing its results with the analytical diffraction coefficients for an infinite 3-D right-angle perfect electric conductor wedge obtained using the uniform theory of diffraction. Then, we apply the new method to calculate numerical diffraction coefficients for a 3-D infinite right-angle dielectric wedge, covering a wide range of incident and scattering angles. Finally, we show means to compactly store the calculated diffraction coefficients in a manner which permits easy interpolation of the results for arbitrary incidence and observation angles.