Vortex Electromagnetic Radar Imaging and Adaptive Resource Scheduling Based on Uniform Concentric Circular Arrays

Vortex electromagnetic radar can achieve high-resolution imaging according to the approximate dual relationship between orbital angular momentum (OAM) mode variable and target azimuth variable. The azimuth resolution is determined by the number of OAM modes, which is limited in radar systems. In addition, the inconsistent pointing of the vortex beam carrying different OAM modes limits the echo energy, further influencing the azimuth resolution. However, existing research has not comprehensively considered the impact of the number of OAM modes and beam pointing on imaging performance, making it difficult to obtain high-resolution images using a few suitable OAM modes and hard to allocate radar resources for multitarget imaging reasonably. To solve the above problems, a new vortex electromagnetic radar imaging and adaptive resource scheduling method based on uniform concentric circular arrays (UCCA) is proposed in this article. First, a 2-D sparse imaging method based on UCCA with stepped frequency chirp signal (SFCS) is proposed, where the joint selection of array number and OAM modes is accomplished with the beam pointing modulated by different array radii. By this method, target imaging can be achieved with a small number of OAM modes and SFCS sub-pulses. On this basis, according to the prior target feature information, an adaptive resource scheduling optimization model is established for multitarget imaging, and a corresponding two-step solution method is proposed. As a result, array, OAM mode, and frequency resources can be reasonably allocated among targets, and high-resolution images can be obtained. The effectiveness of the proposed method is demonstrated by simulations.