Acoustic carpet cloaking by using a metasurface made of graded Helmholtz resonators is characterized experimentally. This thin metasurface, placed over the object to hide, is designed such that the reflection phase shifts of the resonators at the resonance frequency are tuned to compensate the shape of the object to cloak. Experimental as well as numerical results show the efficiency of the cloak at the resonance frequency. The reflection of a short pulse is also inspected to characterize the broadband character of the cloak.
(a) Experimental setup. (b) Scheme of the metasurface carpet cloak. (c) Picture of the 3D-printed unit cell
Experimental and numerical results for the acoustic field