All-dielectric Material Transmitted Lens for Orbital Angular Momentum Generation

Currently, electromagnetic (EM) waves carrying the orbital angular momentum (OAM), called as vortex beams, are generated by helicoidal parabolic antennas antenna arrays or metasurface. However, the traditional OAM generators are generally limited by a narrow operation bandwidth, complicated feeding structures or high loss. In this paper, we propose an all-dielectric transmitted lens by the concept of space transformation. The permittivity distribution of the lens is calculated by space transformation concept, which is applied for theoretical design of the lens. A vortex beam is transformed from the plane wave propagating through the calculated medium. The phase and magnitude distribution patterns are numerically simulated and reported in order to validate the proposed microwave lens over a wide frequency range spanning from 12 GHz to 18 GHz.