3-D ISAR Imaging of Maneuvering Targets Based on Signal Separation in the Monopulse Radar

Compared with 2-D radar imaging, the 3-D imaging provides richer target information and holds broader application potential. However, the existing monostatic 3-D inverse synthetic aperture radar (ISAR) imaging techniques for maneuvering targets often rely on complex scatterer association algorithms with limited robustness, which hinders the practical application. The monopulse technique is known for its high angular accuracy and is a promising solution for 3-D imaging. However, when applied to maneuvering targets, the resulting image exhibits angular glint and time-varying angle, which severely affect the angle estimation accuracy. To address these challenges, this article proposes a 3-D ISAR imaging framework based on signal separation combined with angular motion compensation in the monopulse radar. First, a signal separation method based on the RELAX algorithm is introduced to separate individual components. Subsequently, the amplitudes of the difference channel for each component are estimated to extract the angular information. To mitigate the impact of time-varying angular terms, a motion compensation method combined with an angular coefficient estimation method is proposed. Finally, by synthesizing the angular information and geometric relationships, the 3-D image is reconstructed. The proposed method can produce accurate 3-D reconstructions with robust performance for the maneuvering targets. The experimental results validate the effectiveness and performance of the proposed method.