The generation and recording of electromagnetic waves by georadar
systems are complex phenomena. To investigate the characteristics
of typical surface georadar antennas operating in realistic environments,
we have developed an antenna simulation tool based on a finite-difference
timedomain (FDTD) approximation of Maxwell''s equations in 3-D Cartesian
coordinates. The accuracy of the algorithm is validated with respect
to laboratory measurements for comparable antenna systems. Numerically
efficient and accurate modeling of small antenna structures and high
permittivity materials is achieved via subgridding. The antenna panels
are modeled either as perfect electrical conductors or as thin material
sheets of finite, spatially variable electrical conductivity. We
simulate the radiation characteristics of a wide range of common
surface georadar antenna types ranging from thin-wire antennas to
bow-tie antennas with arbitrary flare angles.