We experimentally demonstrated an alternative approach of invisibility cloaking that can combine technical advantages of all current major cloaking strategies in a unified manner and thus can solve bottlenecks of individual strategies. A broadband cylindrical invisibility cloak in free space is designed based on scattering cancellation (the approach of previous plasmonic cloaking), and implemented with anisotropic metamaterials (a fundamental property of singular-transformation cloaks). Particularly, nonsuperluminal propagation of electromagnetic waves, a superior advantage of non-Euclidian-transformation cloaks constructed with complex branch cuts, is inherited in this design, and thus is the reason of its relatively broad bandwidth. This demonstration provides the possibility for future practical implementation of cloaking devices at large scales in free space.

Abstract-In this paper, the backscattering properties of a perfect electric conducting sphere coated with layered anisotropic media whose constitutive parameters are close to nihility are investigated. We show that the backscattering is more sensitive to the radial constitutive parameters than to the tangential ones. Compared with isotropic case, the anisotropic media with small axial parameters have the potential to yield more reduction of backscattering magnitude on coated perfectly conducting spheres.

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Abstract-The magnetic properties of the metamaterial composed of both periodic and aperiodic closed rings are studied. Experimental results validate that metamaterials with 0 < µ < 1 can be nondispersive in a wide frequency range. The magnetic properties are insensitive to disorders of the closed rings, e.g., the position disorders and the size disorders. The related causality issue is also discussed.