Mode‐switchable orbit angular momentum waves by mechanically rotating 2 bit phase quantization transmitarray.

In this article, mode‐reconfigurable orbit angular momentum (OAM) waves is developed by mechanically rotating a 2 bit phase quantization (0°, 90°, 180°, and 270°) transmitarray (TA) with size 6.2λ0 × 6.2λ0 × 0.98λ0 (λ0 wavelength in free space). The TA consists of three‐layer metasurfaces (MSs), which are in the top, middle, and bottom layers, respectively. The TA is excited by a horn. The top layer MS converts the spherical wave from the horn into plane wave. The middle and bottom layers are same, and they together convert the plane wave into OAM wave with mode l, and then reconfigurable mode can be achieved by rotating the bottom layer MS. To the knowledge of the authors, it is the first time to design mechanical OAM mode reconfigurability by phase quantization TA. As example, two TAs are designed for reconfigurable modes at 15.5 GHz: (1) Among l = 1, 0, −1. (2) Among l = 2, 0, −2. The TAs have the following advantages: high gain (15.1–21.5 dBi), high aperture efficiency (the highest up to 29.2%), high purity (92.67%–98.93%), and small size (6.2λ0 × 6.2λ0). The measured and simulated results agree well, and validate the design method. The developed OAM mode reconfigurable TAs have potential application for future high capacity communication. [ABSTRACT FROM AUTHOR]