Design of Multiple-Polarization Reflectarray for Orbital Angular Momentum Wave in Radio Frequency

In this letter, a novel multiple-polarization reflectarray that carries orbital angular momentum (OAM) is proposed. The coupling between the linear or circular polarization and OAM is realized using an orthogonally independent modulation of the especially designed reflective unit, with the polarization angle of the linearly polarized feed incident to the reflectarray properly changed. According to the principle of time-delay phase compensation for an air-fed reflectarray, the formula of an OAM linear-circular polarization conversion is derived. Considering the phase difference between the feed and the element placed on the reflectarray and the phase response curve versus the element length, the configuration of the reflectarray is determined. Through the numerical simulation and experimental measurements, the predesigned concept is demonstrated.