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 paper, 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 three - dimensional (3D) Omega - K imaging algorithm for multi - scatter point targets, based on fractional OAM. This 3D 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 2D electromagnetic vortex SAR. Then, by processing the two-dimensional 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 3D reconstruction of the target. Experimental simulations validate the algorithm’s effectiveness, with successful 3D imaging of point targets.