Broadband orbital-angular-momentum (OAM) multiplexing is of great interest due to its ability to increase channel capacity in wireless communications. However, broadband OAM-mode-reconfigurable transmitarrays have yet to be developed. Here, a broadband 1-bit electronically reconfigurable transmitarray for OAM-mode-reconfigurable beam generation is proposed, fabricated, and tested. The OAM transmitarray includes $20\times 20$ elements with a 1-bit phase resolution, each element is controlled by two $p$-$i$-$n$ diodes with a minimum insertion loss of 0.9 dB and a 3-dB transmission bandwidth of 17.1%. A nearly perfect 1-bit phase resolution is obtained by reversing the current. The OAM mode can be switched between $l=+1$ and $l=+2$ based on a steering-logic board. Both simulation and experiment results show the transmitarray can generate a broadband OAM-mode-reconfigurable beam from 9.5 to 10.5 GHz. The proposed transmitarray may have potential applications in broadband OAM-multiplexing communications.

• Received 13 December 2020
• Revised 3 March 2021
• Accepted 30 March 2021

DOI:https://doi.org/10.1103/PhysRevApplied.15.044035