A Forward-Looking High-Resolution GPR System

A high-resolution ground penetrating radar (GPR) system was designed to help define the optimal radar parameters needed for the efficient standoff detection of buried and surface-laid antitank mines. The design requirements call for a forward-looking GPR capable of detecting antitank mines in a 5 to 8 meter wide swath, 7 to 60 meters in front of a mobile platform. The system has a resolution goal of 15 cm both in range and azimuth. The range and azimuthal resolutions are achieved by using a 2.7 GHz bandwidth and a 4 meter synthetic aperture, respectively. The system uses a fully coherent homodyne stepped-frequency approach with a modulation scheme that produces range dependent power gain to partially offset range losses. Transmit power of 1 to 10 W is available over the entire band, and a large effective dynamic range was built into the receiver. The antennas are mounted on separate transmit and receive computer-controlled high-precision linear drives for creating the synthetic aperture. A data scan entails stepping through all the frequencies, polarizations, and antenna positions before the van is driven forward for the next scan. Preliminary data, the resulting images, and preliminary work on automatic target detection will be presented.