Design and development of a 1-bit dual-mode metasurface for sub-6 GHz wireless communication systems

This paper presents design and development of 1-bit dual-mode metasurface for sub-6 GHz wireless communication systems. The design consists of four distinct configurations: two for transmission and two for reflection mode. Diode-based phase switching capability was initially considered in simulations, however the final prototype was fabricated with fixed stripline phase configuration. These striplines replicate diode ON/OFF states to validate the phase-switching logic to minimize the cost and design complexity. The proposed unit cell works effectively in both transmissive and reflective modes while maintaining a phase shift of 180° ± 20° throughout its operational bandwidth. Despite its multi-layer structure and dual-mode operation, the proposed unit cell has low insertion loss of around 0.4 dB and 0.21 dB in transmissive and reflective mode, respectively at the central frequency. The unit cell achieves 3 dB fractional bandwidth of 16% in transmissive mode and 12% in reflective mode. A 10 × 10 elements array simulation has been carried out to demonstrate pre-defined beam steering capabilities with ± 60° in both transmissive and reflective modes providing coverage of 240° out of complete 360°. The gain of the source antenna is enhanced by more than 6 dB across the operational bandwidth, with a fluctuation of 3 dB. The performance of the proposed metasurface is successfully validated through both numerical simulations and experimental results, with a good agreement observed in the overall radiation pattern and characteristics.