Generation of Multiple OAM Modes Using Time-Modulated Concentric Circular Arrays

The method of generating multiple orbital angular momentum (OAM) modes using time-modulated concentric circular arrays (TMCCAs) is proposed and analyzed. TMCCAs consist of RF-switch-controlled elements located on multiple concentric rings. Unlike conventional concentric phased arrays, TMCCAs introduce the phase shift required for vortex waves by periodically energizing elements with RF switches. Results show that TMCCAs can simultaneously generate multiple OAM modes at harmonic frequencies.