Multipass Interferometric ISAR for Three-Dimensional Space Target Reconstruction

The 2-D inverse synthetic aperture radar (ISAR) images of space targets vary with the viewing angles and are not suitable for automatic target recognition (ATR), thus requiring 3-D reconstruction techniques. Conventional 3-D space target reconstruction techniques either use monostatic radar with incoherent processing for target retrieval or exploit multistatic radar but coherent processing for target reconstruction. In this article, we combined aspects of monostatic radar and coherent processing to investigate the coherent reconstruction of 3-D space target reflectivity with monostatic radar. Space objects periodically revisit the same ground area. Multipass interferometric synthetic aperture radar (multipass InSAR) uses repeat-pass synthetic aperture radar (SAR) acquisitions on the same ground area with a spaceborne SAR system for 3-D ground surface reconstruction. Motivated by multipass InSAR, we used multipass ISAR acquisitions on the same space target with monostatic ground radar for 3-D space target reconstruction. We proposed a multipass interferometric ISAR (multipass InISAR) algorithm that exploits inverse synthetic aperture technology for range-azimuth focusing and interferometry for the third dimension reconstruction. The elevation estimation performance of the algorithm is analyzed. Simulation results on the Tiangong-2 space lab, Jason-3 geodetic satellite, and ENVISAT remote sensing satellite validate the effectiveness of the proposed algorithm.