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Subgridded FDTD Modeling of Ground Penetrating Radar Scenarios Beyond the Courant Stability Limit

This paper presents an efficient 3-D finite-difference time-domain (FDTD) subgridding scheme that is free of the Courant–Friedrichs–Lewy stability condition, for the modeling of ground-penetrating radar (GPR) scenarios in lossy dispersive media. Spatial filtering of FDTD fields within the subgrid is employed to render the time step independent of the cell size in the fine-cell subgrids. This process is applied with minimal modification of the original FDTD code, no implicit operations, and very modest computational overhead. Moreover, multiterm dispersion is included to model practical GPR scenarios involving the detection of realistic scatterers within dispersive soil. Several numerical examples are provided to demonstrate the potential of the proposed method as a powerful GPR modeling tool.