A physical modeling study to analyze the horizontal resolution limits of GPR reflection imaging

Physical modeling studies at the laboratory scale close the gap between computer simulations and field experiments. In ground-penetrating radar (GPR), such physical models are, for example, useful to study wave propagation phenomena, to evaluate mathematical models, and to develop tools for data analysis, processing, and interpretation. Here, we present an experiment, which has been designed to study the resolution capabilities of GPR. Our model consists of well-defined targets (styrofoam and metallic objects) located in a homogenous background medium (water-filled tank). Collecting 2D/3D GPR data using 1 GHz antennas across this model, allows us to analyze real-world data sets (e.g., in terms of waveforms and noise characteristics) and to evaluate basic theoretical concepts as they are known from the literature to specify the resolution limits of GPR. Here, we focus on the analysis of horizontal resolution and compare our results (i.e., unmigrated and migrated data) to basic Fresnel zone concepts. Our results demonstrate the principal applicability of these concepts to estimate the resolution limits of GPR data. Furthermore, they illustrate that a proper migration scheme is essential to obtain a well focused GPR with optimal resolution capabilities, which we estimate to be in the order of half of a dominant wavelength.