An AlGaAs Diode-based Reconfigurable Intelligent Surface for mmWave Communication

The role of Reconfigurable Intelligent Surface (RIS) has been significant for Millimeter Wave(mmWave) applications. The RIS provides the potential to redirect the incident wave with beamforming using programmable and reconfigurable devices. In this work, an AlGaAs diode-based single-layered RIS unit cell is proposed with beamforming operation at mmWave communication in the reflection mode. The unit cell, with a size of $10 \times \mathrm{l}0 \times \mathrm{l}.6\mathrm{m}\mathrm{m}^{3}$, is integrated with two AlGaAs-based pin diodes as reconfigurable elements. It provides a resonance bandwidth of 31.5-32.85 GHz (1.35 GHz) and 31.5-32.34 GHz (0.84 GHz) with a 31.9 GHz resonant peak in On and Off-states respectively. The variation in the reflection beams is observed due to the reflection phases $0^{0}$ (On-state) and $15^{0}$ (Off-state). The proposed single-layered structure is designed and simulated using a CST full wave simulator with AlGaAs diode equivalent lumped elements. Hence, the designed RIS unit cell is suitable for mmWave communication, which provides radiation coverage.