Tomographic Radar Imaging Techniques

When conventional range-doppler radar processing is used to obtain microwave images of rotating objects, the rotation must be limited to small angles because of problems associated with motion through resolution cells. However, if tomographic processing is used, the rotation can be through large angles. Tornograpbic reconstruction is a natural way to obtain images in any synthetic aperture two-dimensional system, This paper presents two tomographic reconstruction algorithms. The first algorithm employs a modified version of the filtered back-projection (FBP), the most popular image reconstruction technique in x-ray tomogrpahy, applied to the target range profiles. In the second algorithm, termed coherent Doppler tomography (CDT), coherent Doppler profiles of the target measured at different frequencies are back-propagated to obtain highly resolved radar image. Tomographic reconstruction is shown, by means of computer simulation, to provide uniformly high resolution over the object space. The typical radial image degradation of conventional range-Doppler processing is completely absent.