Vortex Wave Antenna Based on Slot Radiation

In this paper, we present an antenna which can radiate vortex waves by introducing rotationally symmetrical four slits on an irregular pentagon patch. The four slots are located on the maximum inscribed circle to determine the rotating center. In order to further improve the mode purity, the ground plate is reduced to a circle. In this case, the main radiation direction of the edge fields is changed from the original +z to the -z, so that the negative influence of the edges field in the +z direction is reduced. The designed antenna produces good performance of -1 order OAM waves at 7.6GHz with mode purity higher than 50%.