Synthetic aperture radar for the detection of shallow buried objects

This paper illustrates the use of synthetic aperture (SAR) processing techniques applied to step-frequency ground penetrating radar (GPR) for the detection of small buried objects. Conventionally GPR systems operate with the antennas held against the surface of the ground for good coupling and depth of penetration; clearly a mode of operation in which the antennas do not make direct contact with the ground is preferable for mine detection. We have shown that small buried objects can be detected with the antennas elevated off the ground and tilted sideways to the direction of motion. The radar covered the band 1-2 GHz, giving a resolution cell size of 5 to 15 cm which is suitable for detecting objects similar in size to anti-tank mines. Results showed that small objects can be more easily distinguished from clutter after SAR processing than in the unprocessed high resolution range profile history. A nonmetallic object with diameter of 24 cm was clearly distinguishable from clutter when buried about 6 cm in dry sand