Experimental near field OAM-based communication with circular patch array

A short range experimental communication system, based on Orbital Angular Momentum (OAM) multiplexing, is presented. We characterize circular arrays of patch antennas designed to transmit and receive OAM electromagnetic fields, reporting new results on communication links based on such antennas. We also experimentally study the antennas tolerance to misalignment errors (angular tilt and lateral shift) within which OAM multiplexing can be efficiently exploited. Starting from these results, we finally propose an application to short range communications of OAM-based systems that can lead to a high level of security in the information exchange.