The generation and recording of electromagnetic waves by typical ground-penetrating
radar (GPR) sounding systems is complex and the effects of the antennas
on the recorded data are not well understood. To address this problem,
we present a versatile and efficient GPR system simulation tool.
This algorithm is based on a finite-difference time-domain (FDTD)
approximation of Maxwell's equations and allows us to model realistically
the radiation characteristics of a wide variety of typical surface
GPR antenna systems. The accuracy of the algorithm is benchmarked
and validated with respect to extensive laboratory measurements for
comparable antenna systems. Given the flexibility of this GPR modeling
software, we anticipate that it will be useful not only for the design
and interpretation of GPR surveys, but also for the design of novel
GPR sounding systems.