Dual-band Beamforming Metasurface with Complex-Amplitude Modulations

Beamforming is one of the key technologies to improve the quality and reliability of the communication systems. In this work, a beamforming metasurface is proposed to generate the flat-top patterns at 7 and 11.4 GHz. The metasurface is composed of a dual-band circularly polarized unit cell, which can realize the simultaneous and independent complex-amplitude modulations of the incident waves. By arranging appropriate amplitude and phase distributions in the metasurface, we can get the desired flat-top patterns at both frequencies. The full-wave simulated results show that the metasurface can achieve 50° beamwidth and 1.5 dB average fluctuation at both frequencies, and the side lobe levels are less than -10 dB and -18 dB at the lower and higher frequencies, respectively.