Sidelobe Suppression and Beam Collimation in the Generation of Vortex Electromagnetic Waves for Radar Imaging

For the electromagnetic (EM) vortex imaging purposes, the sidelobe suppression and the beam collimation method in the generation of orbital angular momentum (OAM) beams is proposed. Based on the concentric ring array, the objective function for the generic algorithm is defined to calculate the signal amplitude for each ring. Comprehensive simulations are conducted to validate the effectiveness of the proposed method. Results show that the main lobes of the radiation pattern of different OAM modes are collimated in the same direction and the sidelobes are all lower than –20 dB. Furthermore, the imaging model of the concentric-ring array is established, and the target image is obtained through numerical simulations. The work can advance the development of the EM vortex imaging technique and novel radar detection technology as well.