Reconfigurable Reflection-Transmission Surface for Dual-Beam Direction and Angular Control in mmWave Systems

A reconfigurable reflection-transmission surface (RRTS) is proposed for dual-beam direction and angular control in millimeter-wave (mmWave) systems. The RRTS element is designed to operate within the frequency range of 23.9 to 27.7 GHz for reflection mode and 22.8 to 29.0 GHz for transmission mode, corresponding to the 26 GHz mmWave band (n258: 24.25-27.5 GHz). The element consists of a copper hexagonal ring structure on the top layer and a hexagonal patch on the bottom layer. Two p-i-n diodes are integrated into the design to electronically control the 180° phase difference of each mode. A 10 × 20 array of RRTS elements is designed and analyzed. The results demonstrate that the proposed RRTS enables reconfigurable operation in reflection (backward space), transmission (forward space), and hybrid (full space) modes, utilizing different periodic coding sequences to allow precise control over dual beams, enabling independent steering and scanning. The beam deviation error is found to be less than ±1.6° for both reflection and transmission modes, and less than ±5° for the hybrid mode, as compared to theoretical predictions.