Mantle cloak: Invisibility induced by a surface

The exotic wave interaction of metamaterials has been recently applied to various cloaking applications, but the metamaterial realization in practical cloaks is still far from ideal. Current fabrication techniques are inherently based on the volumetric properties of metamaterials, which require a non-negligible electrical thickness. I introduce here the idea of surface cloaking, showing that a patterned metasurface may produce similar cloaking effects in a simpler and thinner geometry. The currents induced on a passive surface are tailored to drastically suppress the visibility of a given object.

Figure 1

(Color online) Examples of patterned metallic geometries that may realize a mantle cloak.

Figure 2

(Color online) Variation in the total scattering cross-section of a dielectric sphere with $\epsilon =10$ and $2a={\lambda }_0/5$ with: (a) the surface reactance of a mantle cloak; (b) the normalized frequency of operation for a cloak with $a_c=1.1a$ and $X_s=175\Omega$.

Figure 3

(Color online) Distributions of the: (a) amplitude of electric field on the $H$ plane; (b) phase of magnetic field on the $E$ plane, for the three scenarios of: a cloaked sphere (left), the same sphere, but uncloaked (center), an enlarged uncloaked dielectric sphere with $a=a_c$ (right). Brighter colors correspond to higher values of the fields. The panels are all in the same scale for a fair comparison.

Figure 4

(Color online) Analogous to Fig. 2a, but for a conducting sphere of same size.

Figure 5

(Color online) Analogous to Fig. 3, but for a conducting sphere of same size.

Figure 6

(Color online) Full-wave simulation results for a realistic quasi-isotropic inductive FSS cloak covering the dielectric sphere of Fig. 2.