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Detecting underground metallic objects of different sizes using synthetic aperture radar

Detecting underground/subsurface metallic objects such as landmines and IEDs (improvised explosive devices) using efficient and effective inspection techniques is crucial in demining and mine clearance missions. The use of microwave/radar sensors in remote sensing represents a new approach to reduce demining risks and to improve efficiency. To achieve the goal, electromagnetic signatures of underground metallic objects must be thoroughly studied. The objective of this paper is to use synthetic aperture radar (SAR) imaging to investigate the size effect of an underground metallic object buried in SAR images at three ranges (15 cm, 30 cm, and 60 cm). Three different sizes (diameters = 7.6 cm, 15.2 cm, and 20.3 cm) were used and buried inside a container (sandbox) filled up with dry sand. A 10-GHz SAR imaging radar sensor was applied to generate all SAR images inside an anechoic chamber. It was found that SAR amplitude decreases with the increase of radar range. In addition, reconstructed distribution of SAR amplitudes depended on the size of underground steel disk specimens. SAR amplitudes (maximum and integrated) were related to the range and modeled by empirical equations.