A Method to Improve OAM Mode Purity Based on Antenna Array

OAM (Orbital angular momentum) waves have infinite orthogonal modes. The azimuth information of the target and the number of modes have dual relations. Thus, OAM waves have huge potential in improving imaging resolution. However, OAM waves generated by many methods in microwave field have the problem of superfluous modes. Thus, a method based on antenna array to reduce the number of superfluous OAM modes is proposed in this paper. Besides, the antenna array can improve the mode purity of OAM waves.