We demonstrate active millimeter wave (mmWave) 3D synthetic aperture radar (SAR) imaging through common building and construction materials. Human-safe mmWaves penetrate many non-metallic construction materials to a surprising degree, allowing for non-destructive structural and utility integrity analysis. We demonstrate that mmWave imaging can be used to locate pipes, electrical wiring, wood and metal studs, rebar, and other structural elements and utility infrastructure embedded in building walls. Millimeter wave imaging can also be used to find contraband items hidden inside walls. In addition, liquid water strongly reflects mmWave energy, allowing the localization of potential leaks. We present K-Band (15 - 26:5 GHz) and V-Band (50 - 65 GHz) 3D SAR images of brick, drywall, tile, wood, and concrete wall test structures. Imaging was performed using a 2D raster scan of a bistatic horn antenna pair, yielding a 3D SAR image with a voxel resolution of approximately 1.5 cm (K-band) and 5 mm (V-band).
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