Design and analysis of the trapeziform and flat acoustic cloaks with controllable invisibility performance in a quasi-space

Abstract

We present the design, implementation and detailed performance analysis for a class of trapeziform and flat acoustic cloaks. An effective large invisible area is obtained compared with the traditional carpet cloak. The cloaks are realized with homogeneous metamaterials which are made of periodic arrangements of subwavelength unit cells composed of steel embedded in air. The microstructures and its effective parameters of the cloaks are determined quickly and precisely in a broadband frequency range by using the effective medium theory and the proposed parameters optimization method. The invisibility capability of the cloaks can be controlled by the variation of the key design parameters and scale factor which are proved to have more influence on the performance in the near field than that in the far field. Different designs are suitable for different application situations. Good cloaking performance demonstrates that such a device can be physically realized with natural materials which will greatly promote the real applications of invisibility cloak.

Non-closed acoustic cloaking devices enabled by sequential-step linear coordinate transformations

“…Cloaks based on linear coordinate transformation have homogeneous constitutive parameters with finite anisotropy which obviates the need to space dependent materials. Till now, besides huge amount of theoretical investigations to advance of cloaks [24][25][26][27][28], several researches experimentally demonstrated acoustic carpet cloaks via homogeneous fluid like materials. For example, perforated plastic plates have been applied for 2D [29] and 3D [30] ground plane cloaks in air-borne acoustics and steal strips [31] or brass plates [32] have been proposed for underwater acoustics.…”

“…Cloaks based on linear coordinate transformation have homogeneous constitutive parameters with finite anisotropy, which obviates the need for space dependent materials. So far, in addition to huge amount of theoretical investigations to advance of cloaks [24][25][26][27][28] , several studies experimentally demonstrated acoustic carpet cloaks via homogeneous fluid-like materials. For example,…”

Design and demonstration of an underwater acoustic carpet cloak

“…The device modifies the acoustic signature of the target and mimics the acoustic field obtained from a reflecting plane, so that the cloaked target is indistinguishable from the reflecting surface. The concept of the carpet cloak was firstly introduced in context of electromagnetics 8–20 and rapidly extended to acoustics 21–31 . It was firstly proposed as a quasiconformal carpet cloak 8–15 .…”