Waveguide studies of soil modification techniques for enhanced mine detection with ground-penetrating radar

Abstract

Waveguide studies of the effectiveness of soil modification techniques for non-metallic mine detection with ground penetrating radar are described. Visibility improvements for a nylon target buried in sand are considered as varying amounts of water or liquid nitrogen are added to the sand. Experiments are performed in an S-band waveguide (2.6 - 3.8 GHz), and results show that increased water content improves shallow buried target visibility initially due to increased dielectric contrast between the target and background medium, but eventually obscures target responses due to increased loss. Initial tests of the addition of liquid nitrogen show reduced loss in the high moisture content case, so that targets can again be made visible. Analytical model results are also presented for the experimental configuration and found to be in good agreement with measured data, and further studies of soil modification effects with the analytical model are performed. A finite difference time domain (FDTD) electromagnetic model for more complicated geometries involving general target shapes and inhomogeneous water contents is also described.