Radio vortex electromagnetic beam generation based on circular patch array antenna

The vortex electromagnetic wave has a new degree of freedom named orbital angular momentum (OAM), which arises from the vortex phase term. Recently it has received intensive attention in the application to the wireless communication field. In radio waves, the array antenna is an effective method to generate vortex electromagnetic waves carrying orbital angular momentum. We proposed a new design of patch array antenna carrying orbital angular momentum at 6 GHz. In this design, eight proximity-fed circular patches arranged on a circle with equidistant space. By controlling the phase delay, we got OAM modes of quantum number 0, 1, 2, 3, 4, and obtained the vortex electromagnetic wave carrying orbital angular momentum. In addition, the appropriate array radius and feed transport line were two keys to generate good properties of vortex waves carrying orbital angular momentum.