Design of a 1 Bit Broadband Space-Time-Coding Digital Metasurface Array for Beam Scanning

In this paper, a 1 bit broadband space-time-coding digital metasurface array is proposed for real-time beam scanning. The metasurface element is composed of two layers of substrate, one PIN diode, a slotted patch, a reflecting ground, and DC biasing circuits. By method of changing the PIN diode states ON and OFF with different voltages, the resonance characteristics of the metasurface element are further altered. After properly designing of structural parameters of the element, it successfully achieves a stable 180° phase shift within 7.71 - 9.43 GHz. Furthermore, it is capable of designing broadband real-time beam scanning antenna arrays. A space-time-coding metasurface with a 0.256-m square aperture is designed and simulated. Illuminated by a y-oriented horn, the designed metasurface array realizes the scanned beams from 0° to 60° with the maximum gain of 22.13 dB. Moreover, the space-time-coding metasurface obtained broadband 1-dB gain bandwidth of 21.43% from 7.5 GHz to 9.3 GHz. Therefore, we believe that excellent performance improvement is making it more potential for wireless communications.