Fast and accurate solution of time domain electric field integral equation for dielectric half-space

In this work, an FFT-accelerated MOT solver is used to analyze broadband scattering phenomena in a half-space environment. The multilevel space-time FFT scheme accelerates both the matrix-fill and marching times by exploiting the translational invariance of the underlying integral kernel through the use of uniform spatial meshes. All time domain Green´s functions are computed by inverse Fourier transforming their frequency domain counterparts, which, in turn, are computed by adaptive evaluation of Sommerfeld integrals. In what follows, the proposed method is applied to the analysis of transient scattering from PEC bodies residing above a dielectric half-space. The method is flexible enough to be used in the analysis of layered media with more complicated Green´s functions and can be extended to nonuniformly meshed scatterers using the time domain adaptive integral method.