Near-surface radar pulse propagation in complex terrain environments: preliminary results

In a previous study Liu and Arcone [1] discussed the effects of a near-surface thin layer on the lateral propagation of a radar pulse with 2-dimensional numerical models. They concluded that the near-surface stratigraphic structure plays an important role when it combines with different antenna polarization modes. Numerical modeling successfully simulated the wavefield dispersion caused by the existence of the surface thin layer. In this paper the analysis has been extended to include the azimuthal effects in radiation patterns with the use of a 3- dimensional (3-D) pseudospectral time domain (PSTD) numerical modeling technique to understand radar pulse propagation in a similarly complex environment. In these preliminary test cases, the propagation of radar pulse generated by a horizontal dipole aligned with the r-direction was modeled in 3 dimensions. The model of material properties includes (i) a uniform half-space with either higher or lower conductivity, and (ii) a thin dielectric layer overlaid on the half space. A significant electric field in the vertical direction (Ez-field) was observed in the end-tire direction for all cases. As predicted by the analytic solution, the Ex-field reaches the minimum in the end-fire direction and maximum in the broadside direction. The thin layer complicates the waveform; however, the fundamental radiation patterns remain the same with the half-space case. We will model the effect of geometric and material heterogeneities for more complicated terrain environments in the near future.