An acoustic Maxwell’s fish-eye lens based on gradient-index metamaterials
Yuan Bao-guo1, 2, Tian Ye1, Cheng Ying1, 3, †, 
, Liu Xiao-jun1, 3, ‡,
, Liu Xiao-jun1, 3, ‡, Schematic diagram of the space-coiling acoustic metamaterials (SAM) unit.
