Single-layer dual-frequency unit for multifunction OAM reflectarray applications at the microwave range.

This Letter presents a single-layer, dual-frequency unit for generating orbital angular momentum (OAM) in the microwave range. The unit cell consists of a square frame and two concentric rings with branches. The developed units can produce multifunctional OAM with required OAM mode, beam number, and direction. To demonstrate this versatility, three reflectarrays operating at dual frequencies are designed, and one is fabricated and measured to validate the design. The reflectarray has the following advantages: high gain (15.4dBi at 10 GHz, 20.3dBi at 20 GHz), high aperture efficiency (13.53% at 10 GHz, 10.33% at 20 GHz), low divergence angle (7.5°at 10 GHz, 6° at 20 GHz), small size, and compactness in the form of a single-layer structure. The designed multifunctional reflectarray has potential applications in remote sensing, point-to-point communication, satellite communications, and others.