Dual-band filtering and enhanced directional via tunable acoustic metamaterial antennas

The detection of acoustic signals in strong background noise plays a crucial role in industrial non-destructive, mechanical equipment health monitoring and acoustic communication. The major bottleneck of this technology lies in the limited high-sensitivity and high-directivity of acoustic sensors. Here, this study proposes a tunable acoustic metamaterial antenna (TAMAA) with a double bandgap and near-zero refractive index. Different from the traditional geometric scatterer, a gear-shaped structure is introduced to enhance the controllability of the acoustic system. We theoretically demonstrate the physical properties of the structure with a double bandgap and near-zero refractive index. Remarkably, the gear-shaped honeycomb lattice structure exhibits an adjustable bandgap region, which enables the multiplexing of both acoustic shielding and acoustic enhancement functions by controlling the rotation angle of the scatterer. Furthermore, through numerical computational and experimental studies, we demonstrate that the proposed TAMAA exhibits dual-band filtering capabilities and provides excellent acoustic directional enhancement. Moreover, it allows for the recovery of weak acoustic signals even in the presence of extremely low signal-to-noise ratio and strong spatial noise interference. This work breaks through the detection limits of conventional acoustic sensing systems and provides new ideas for the development of acoustic sensing detection.