Multi-mode OAM parabolic antenna with dual feeds

A double-feed OAM parabolic antenna is proposed, consisting of a parabolic antenna, which is designed to reflect the OAM beams onto its surface, a low mode feed which generates vortex waves with l=1,2, and a high mode feed which generates OAM beams with l=3,4. This principle of getting high gain vortex wave is described and verified by simulation. From the results we get, the OAM antenna gains of the four modes are all above 24.7dBi.