Acoustic Transmission Characteristics Based on H-Type Metamaterials

To achieve the artificial manipulation of the acoustic wave front, and to produce high-efficiency acoustic focusing effect, this paper designed an
$H$
-type locally resonant metamaterial structure based on a two-dimensional three-component local resonance unit. The transmission characteristics of acoustic waves in this model were analyzed by using COMSOL, which is a finite element simulation software. We found that the incident acoustic energy was absorbed by the model, and the transmission path was consistent with the model structure. We also found that in different frequencies, the transmission characteristics of acoustic waves were different. The acoustic transmission characteristics improved as the waves approached the resonant frequency. Because of the flexibility and controllability of metamaterials, the structure can be designed according to specific conditions in practical applications to meet the resonant frequency required for transmitting acoustic signals, thus, improving the acoustic transmission efficiency. In addition, if the point excitation source of spherical waves was replaced by the line excitation source of plane waves, a plane acoustic wave focusing phenomenon would occur, which further proved that the local resonance acoustic metamaterial has good focusing characteristics and manipulation characteristics. The result of our research provides a new direction for underwater acoustic imaging, acoustic communication, and acoustic detection.