Additively Manufactured Semipassive Rotman Lens-Based RIS-Assisted mmID Tag System for Beyond-5G Wireless Networks in Complex Environments

The authors present a semipassive Rotman lens-based reconfigurable intelligent surface at 28 GHz for beyond-5G applications. One proof-of-concept prototype is inkjet-printed on a thin Rogers substrate using a masking technique followed by etching. The system is characterized by its autonomous mode switching, power consumption, radar cross section (RCS) against angle, and mid-range performance. This millimeter-wave identification (mmID) tag system detects radio frequency (RF) signals with a half-wave rectifier and retransmits signals in selective directions with a 270-kHz amplitude shift keying modulation. This proposed system consumes 65
$\mu$
W in the detection mode and 143
$\mu$
W in the communication mode, suggesting the potential to be further developed into a fully passive and energy-autonomous system for long-range applications in complex environments. To switch between detection and communication modes, the rectifier oscillates between 6.1 and 9.7 mV, which means that the Rotman lens-based RIS-assisted mmID tag system can operate up to 75 m away for communication mode and 89 m for the detection mode.