An Additively Manufactured Lens Antenna for Orbital Angular Momentum Multiplexing

In this paper, an additively manufactured metal lens antenna for orbital angular momentum (OAM) multiplexing is demonstrated. The lens achieves this functionality by utilizing a novel quadruple-ridged waveguide element, which converts the incident circularly polarized (CP) wave to a transmitted CP wave with the opposite handedness. This conversion enables a full 360° geometric phase tuning range through ridge rotation. Additionally, the waveguide element's height can be adjusted to control the propagation phases of the CP transmitted waves. By combining both geometric and propagation phases, independent control of OAM modes for left-hand CP (LHCP) and right-hand CP (RHCP) vortex beams is achieved. A lens generating <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\boldsymbol{l}={\mathbf{0}}$</tex> OAM beam for RHCP incidence and <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\boldsymbol{l}=+\mathbf{1}$</tex> OAM mode beam for LHCP incidence is simulated for the validation of the OAM multiplexing.