Clutter reduction in GPR measurements for detecting shallow buried landmines: A Colombian case study

Detection of land-mines from ground-penetrating radar data is a challenging task demanding accurate and useful filtering techniques to reduce soil-surface and antenna reflections, which obscure the landmine response. In this paper, we apply and adapt a recently proposed filtering approach to enhance the detection of shallow buried anti-personnel land-mines from data acquired in typical mine-affected soils in Colombia. The methodology combines a radar-antenna-subsurface model with phase-shift migration to filter out antenna and soil-surface effects from off-ground monostatic radar two-dimensional data. Firstly, antenna multiple reflections are removed using linear transfer functions. Secondly, simulated Green's functions accounting for the surface reflection are subtracted. These functions are derived using the relative dielectric permittivity of the surface, which is estimated by full-wave inversion of the radar signal for measurements taken in local land-mine-free areas. Finally, the antenna radiation pattern effect is filtered out by performing phase-shift migration, and information about size and shape is extracted. Data are acquired using a hand-held vector network analyser connected to an off-ground monostatic horn antenna. Typical Colombian targets such as low-metallic anti-personnel land-mines and low- and non-metallic improvised explosive devices are used. Results prove that the proposed technique effectively reduces clutter under non-controlled conditions and yields target features that are useful for detection of these land-mines.