Airborne SAR: The Multipath Effect and Circular SAR

The work is divided in two parts. In the first part, an algorithm to remove the multipath effect in SAR images is presented. Currently, the radome containing the F-SAR antenna is located at the bottom of the plane, which in combination with strong side lobes in the antenna pattern results in a multipath component in the SAR signal. The undesired effects are mainly range undulations in the amplitude and the phase of the processed image. An algorithm to remove the multipath is presented and validated with along-track interferometric and polarimetric data. The second part of the work presents results with circular SAR. With a circular SAR acquisition it is possible to obtain information of the scene with 360° aspect angle observation, resulting in images with sub-wavelength resolution, as well as the possibility to perform 3-D image reconstruction (tomography). Algorithms to perform radiometric calibration and autofocus are presented, as well as 2-D and 3-D processing results with data acquired by both E-SAR (L-band) and F-SAR (X-band) systems