Polarization-Invariant Directional Cloaking by Transformation Optics

Abstract

Abstract-We propose a three-dimensional directional cloak for arbitrarily polarized incoming electromagnetic waves, motivated by the fact that there will be negligible scattering when the direction of impinging wave coincides with the axial direction of a very thin and elongated perfectly electric conducting (PEC) scatterer. The performance of the cloak under different polarizations of incoming waves are numerically investigated. The case in which the direction of incoming wave is perturbed off the ideal direction is also quantitatively studied. Numerical simulations show that the directional cloaking device is able to tolerate a large range of tilted angles of incoming waves.

A Class of Polarization-Invariant Directional Cloaks by Concatenation via Transformation Optics

“…Note that ρ < R 1 < R 2 and ρ L. Moreover, the aforementioned cloaking medium in the physical space as well as its pre-image in the virtual space consists of six components, four quadrilateral frustums and two l ∞ -spherical caps resulting from the difference set of two l ∞ -concentric half-balls. The construction is divided into two steps by following notations of [1].…”

“…In this paper, we propose a new class of three-dimensional PID cloaks via concatenation of cloaking medium components by transformation optics. It combines the advantages of compact-sized directional cloaks in [14,15,18] and the PID one in [1]. The main ingredient is to construct a capsuloid transformed metamaterial consisting of an l p -cylindrical transformation map and two half l p -spherical transformation maps.…”

“…However, the PID cloak suggested in [1] has a restriction of large size in the axial direction compared to the cloaked scatterer since the spatial transformation used to design the metamaterial cloaking medium is essentially isotropic (see [1,Eqs. (1) and (2)]). The performance of this cloaking device depends on the regularization parameter ρ, a measure of the thinness of the PEC scatterer in the virtual space.…”

“…To circumvent the drawback of the dependence of the performance of PSD cloaks on the polarization of incoming electromagnetic waves, the first three-dimensional polarization-invariant directional (PID) cloak has been recently proposed in [1], motivated by the fact that there will be negligible scattering when the direction of the incident wave coincides with the axial direction of a very thin and elongated perfectly electric conducting (PEC) scatterer. The polarization-invariance of PID cloaks make them more desirable than PSD ones in real world applications.…”

“…It improves the construction of the first polarization-invariant directional cloak, introduced by Agarwal et al [1]. The main ingredient is to construct a capsuloid transformed metamaterial consisting of an l p -cylindrical transformation map and two half l p -spherical transformation maps.…”