Radar-based Tomography with Filtered Backprojection Using Attenuation and Time Shift Profiles of a Reference Reflection

In this paper we present monostatic tomographic imaging using a frequency modulated continuous wave (FMCW) radar system operating from 126 GHz to 182 GHz. Instead of an active receiver, we use a metallic corner reflector that is positioned opposite the radar and behind the test object. Both radar and corner reflector are included in a parallel-beam based measurement setup, consisting of electrical translation stages and a turntable to enable measurements at multiple angular positions. The information for reconstruction was obtained by investigating the reflection of the corner reflector in terms of spatially dependent attenuation and time shift caused by a test object. Here, a 3D-printed cuboid made of polylactic acid (PLA) and a polyvinyl chloride (PVC) pipe were placed in the middle of the measurement setup. The image processing is based on the Fourier slice theorem using the filtered backprojection algorithm, whereby the obtained data from the reference reflection is assumed as a projection separately in case of attenuation or time shift.