Development of soil modification techniques for enhanced detection/discrimination

The use of ground penetrating radar (GPR) for the detection and identification of non-metallic mines in low dielectric constant soils is often difficult due to the small dielectric contrast between the target and background media. Previous studies have shown that an optimal soil water content exists for improving target detectability. However, in many cases soil water content is larger than the optimal value so that targets are obscured by medium loss. In this paper the addition of liquid nitrogen to wet soils is considered in order to reduce background medium loss so that targets again become visible. Experimental studies are performed in an S-band waveguide configuration to reduce problem complexity, and an analytical model is applied to interpret experimental results. Results demonstrate that medium loss can indeed be reduced through the addition of liquid nitrogen, but that the depth to which the nitrogen penetrates and flow effects around the target play an important role in data interpretation