An Omega-K 3-D SAR Imaging Algorithm Based on Fractional-Order OAM

Electromagnetic vortex radar, with its unique capacity to carry orbital angular momentum (OAM) and its spiral phase wavefront, offers a groundbreaking approach to achieving super-resolution radar imaging. This letter, grounded in the theory of OAM and plane electromagnetic wave synthetic aperture radar (SAR) imaging, delves into and analyzes SAR imaging technology based on eddy electromagnetic waves. By integrating the characteristics of vortex electromagnetic waves with an orthometric downward electromagnetic vortex SAR imaging model, we have designed a corresponding imaging model and derived the imaging echo formula. Furthermore, we propose a novel 3-D Omega-K imaging algorithm for multiscatter point targets, based on fractional OAM. This 3-D Omega-K imaging algorithm first processes the echo signals of a fixed OAM mode across the entire sampling time to obtain the target’s range and along-track information, maintaining high-resolution in the along-track direction of 2-D electromagnetic vortex SAR. Then, by processing the 2-D data consisting of vortex electromagnetic echoes of various modes transmitted and received at a specific moment, it acquires the target’s azimuth information. Finally, through geometric relationships, it derives the target’s elevation information, accomplishing the 3-D reconstruction of the target. The experimental simulations validate the algorithm’s effectiveness, with successful 3-D imaging of point targets.