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The electromagnetic waves carrying orbital angular momentum can achieve azimuthal resolution for radar imaging without relative motion. However, the difference of main-lobe direction of different modes limits the echo energy. In this letter, the beam steering for vortex beams generated by a uniform circular array is performed by phased array technology. The main lobes of vortex beams carrying different modes can illuminate the target area with this method. The radiation field after beam steering is derived, and the phase distribution is thoroughly investigated. Then, the imaging model is established, and l p regularized least-squares algorithm is employed to reconstruct the two-dimensional target image. Simulation results demonstrate the effectiveness of the proposed beam steering method and that higher resolution can be achieved than Fourier transform method.
Yuan et al. (2016) studied this question.