Active sensing of spatial defects using a microwave imager

The authors discuss microwave sounding of solid dielectric materials to detect and locate internal structural defects or density nonuniformities. The technique uses a reflection-type FM-CW radar system with a sweep range of 8-12 GHz and a sweep duration of 1-100 ms. This system allows for the detection of reflections from defects within the range of 0.1-3.0 m from the radar in most materials of relevance, e.g. fiberglass, timber, concrete, soil, etc. The predicted resolution of the system is 10/sup -3/ m in range, azimuth, and elevation in typical objects.<
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