Two-Dimensional Angular Super-Resolution for Airborne Real Aperture Radar by Fast Conjugate Gradient Iterative Adaptive Approach

The ability of wide-area and fast-revisit observation with beam scanning in both azimuth and elevation dimensions has allowed the airborne real aperture radar to be a hotspot in applications of aircraft formation identification and airborne warning and control system. However, the azimuth-elevation 2-D angular resolution is limited by antenna aperture size. When dealing with azimuth-elevation 2-D angular super-resolution of airborne real aperture radar for aerial targets, the existing super-resolution methods suffer from three problems: model mismatch, range and azimuth-elevation coupling, and high computational complexity, which lead to poor resolution and efficiency for the aerial target resolving. To circumvent this problem, this article proposes an azimuth-elevation 2-D joint super-resolution strategy for airborne real aperture radar. First, we establish an airborne azimuth-elevation 2-D scanning signal model, which accurately represents the migration of velocity in different directions. Then, an azimuth-elevation 2-D range migration correction method is proposed, which eliminates the range and azimuth-elevation coupling. To improve the efficiency of target resolution, a fast conjugate gradient iterative adaptive method is finally derived to rapidly reconstruct the azimuth-elevation 2-D target scatterings. Simulated and real datasets demonstrate that the proposed method is not only suitable for airborne 2-D angular super-resolution, but also achieves a competitive resolution capability with quite lower computational complexity.