Design of 1-Bit Digital Subwavelength Metasurface Element for Sub-6 GHz Applications

This paper proposes a novel 1-bit, electronically reconfigurable, subwavelength metasurface unit cell for sub-6 GHz applications. 180° phase shift is achieved by integrating a single PIN diode in the structure. The unit cell incorporates three layers: The top layer is used for wave reflection, the bottom layer is used for PIN diode placement and DC biasing, and the middle layer acts as a ground plane. The resonance of the unit cell is kept around 3.3 GHz. The magnitude of the reflection coefficient is above 90%. Besides, a phase difference of 180°+20° is achieved over 200 MHz bandwidth. With these characteristics, the proposed unit cell can find its applications in programmable metasurface functions such as beam steering, beam focusing and beam scattering.