Application of 2D and 3D SAR Backprojection Techniques for Intrawall and Throughwall Object Detection

A radar system has been developed to image the interior structures within walls, revealing details such as conduits, piping, and other substructures. This is achieved by moving an antenna system across the wall surface to generate synthetic aperture radar (SAR) images using frequency-domain backprojection. The materials imaged included a copper pipe, a PVC pipe, a wooden beam, and a calibration target. Results showed that all targets, except for the PVC pipe, were clearly visible to the untrained eye. To enhance target isolation from the wall background, background subtraction and differential SAR (DSAR) techniques were applied, both of which effectively highlighted the targets against the wall background. Image contrast was then evaluated as a quantifiable metric of image quality, which is critical for optimising post-processing techniques such as autofocus. Finally, a 3D image of the wall's interior was generated, demonstrating the feasibility of a SAR-based wall scanner and its potential in non-destructive inspection and security applications.