Refraction Effect in SAR Processing for Focused Subsurface Tomography

In synthetic aperture radar (SAR) imaging, the goal of subsurface tomography is to create detailed images of objects and structures underground. In order to obtain well-focused images, the refraction effect must be taken into account during SAR processing. This work proposes an adjusted back-projection algorithm and validates it with simulation and experimental results. The simulation model constitutes an underground air cavity and a multi-circular flight path. The experimental scenario includes a buried quad-corner reflector and an unmanned aerial vehicle (UAV) performing a spiral flight path. Both cases produced well-focused 3D images with the correct positioning of the targets.