Radar detection of near-surface buried metallic reflectors in wet soil

For ground penetrating radar (GPR) sensing, with antennas positioned safely or conveniently above the surface, one must contend with the ground surface reflection as well as reflections from targets sought below it. Employing low enough frequencies to penetrate moist soil means resolution that will often not allow one to distinguish the surface from target return. New measurements at CRREL were analyzed using innovative methods to successfully reveal buried mine and mine-like targets in wet, rocky soil. With broad band short pulse illumination, one method used a simple model that predicted the expected waveforms when surface and target echoes interacted. The other method treated the same cases but proceeds from the observation that the total overlapping surface plus target return is distended in time relative to a reflection from the surface alone. By processing to define and isolate cumulative energy return over time, one could distinguish cases in which targets lay just below the surface. Both methods were successful with moist loamy soil. Performance of the second approach was also good in an extreme case, when seasonal effects were exploited.