Comparison of model-based results with measured data for metal buried mines

Abstract

To detect and identify buried mines, the U.S. Army Research Laboratory (ARL) is using its ultra wideband (UWB) radar in a ground-penetrating mode. Operating in the frequency band from 50 to 1200 MHz, the radar is mounted on a mobile boom lift platform (BoomSAR). This enables it to form synthetic aperture radar (SAR) images as well as measure range profiles. As an integral part of the UWB radar project, ARL is developing an in-house modeling capability. In field tests at Yuma Proving Ground, Arizona, a variety of buried and surface targets were imaged with the BoomSAR, including a minefield of buried and surface metal mines. Most land mines of interest can be accurately modeled as bodies of revolution (BORs). Through consideration of the half-space Green's function, we realized that, there is no cross-polarized scattered field for such BOR targets, (theoretically) and, therefore, such targets are characterized only by co-planarized scattered fields. This feature, which, to our knowledge, has not been recognized before, has important implications for polarimetric SAR imaging of minefields, especially in regions with significant natural clutter (e.g., rocks) that are generally not BORs. This theoretical result will be verified using measured and computed data. Mine dimensions are on the order of one wavelength or less for the frequencies in our bandwidth. The modeling techniques we use for this range of wavelengths are method of moments (MOM) and finite-difference time-domain (FDTD). Model results from our buried BOR MOM code will be compared to the measured data.