A Low‐Rank Modified Imaging Method Based on Gain for Electromagnetic Vortex Radar

ABSTRACT This letter addresses the challenges of electromagnetic (EM) vortex radar imaging related to resolution and prior knowledge, proposing an innovative high‐resolution imaging algorithm in range and azimuth dimensions. Traditional imaging methods, such as the fast Fourier transform (FFT) and spatial spectrum estimation, are hindered by the imaging quality and the requirement for precise estimation of subspace dimension. To address these, this study proposes a novel 2‐dimensional imaging method integrating gain modulation with low‐rank modified multiple signal classification (MUSIC) theory. By employing single‐rank eigen decomposition, the proposed method eliminates dependence on prior information while optimising computational complexity. The proper gain modulation further enhances the multi‐target imaging capabilities. In contrast to FFT and sparse imaging techniques, simulation results and quantitative analyses validated the superior resolution and robustness of the method in complex target scenarios, advancing the EM vortex radar for target observation applications.