Generation of Highly-Pure OAM Beams with Simple Slotted SIW Antenna Array

In this paper, the design and analysis of a slotted substrate integrated waveguide (SIW) antenna array for the generation of orbital angular momentum (OAM) beams is presented. The antenna comprises four U-shaped slots that act as radiators and are placed in a sequentially rotated manner in the top metal plane of the SIW to radiate vortex waves. The proposed antenna array can generate first-order OAM beams with +1 and -1 modes simultaneously, and most importantly, the mode purity of the generated OAM beams is high. Compared to the traditional circular arrays utilized for OAM generation, the proposed antenna uses a simple feeding scheme that doesn't require any external phase shifter, which paves a new way to design the antennas generating OAM.