Radiation and scattering from imperfect cylindrical electromagnetic cloaks

Abstract

The design of electromagnetic invisibility cloaks is based on singular mappings prescribing zero or infinite values for material parameters on the inner surface of the cloak. Since this is only approximately feasible, an asymptotic analysis is necessary for a sound description of cloaks. We adopt a simple and effective approach for analyzing electromagnetic cloaks - instead of the originally proposed singular mapping, nonsingular mappings asymptotically approaching the ideal one are considered. Scattering and radiation from this type of imperfect cylindrical cloaks is solved analytically and the results are confirmed by full-wave finite element simulations. Our analysis sheds more light on the influence of this kind of imperfection on the cloaking performance and further explores the physics of cloaking devices.

Electromagnetic Scattering by Approximately Cloaked Dielectric Cylinder

“…in agreement with [16,19,20] that the scattering from the cloaked body is equivalent to that produced by the body of reduced size with the values of ε, µ modified using a linear transformation for the region of the hidden body. It is to be noted that A n and B n are independent of the outer radius R 2 .…”

“…Another technique is the use of approximate cloaking by transforming the hidden body virtually into a small object rather than a line, as shown in Fig. 1 [14][15][16][17][18][19][20], and for general finite cylindrical shapes [21], however, this leads to some scattering. The analysis of this technique shows that certain resonances result due to the transformed small object, a lossy layer can be used to solve this problem [15,22,23].…”

Resonance effects in broadband acoustic cloak with multilayered homogeneous isotropic materials

“…3 In fact, a similar cloak-induced resonance has also been observed in EM cloaks even if the effect and origin of these resonant states have not been clarified. 11 Here, we examine four representative modes, i.e., mode A ͑B͒ at k 0 a = 0.72 ͑2.22͒ due to the first monopole ͑dipole͒ resonance and mode C1 ͑C2͒ at k 0 a = 3.81 ͑3.97͒ due to the second monopole resonance, as marked in Fig. 1.…”

Imperfect Cloaking Devices Based on Metamaterials

“…The problem of plane wave scattering on an infinite cylinder is a standard one in the scattering theory [13]. Our approach is valid for any type of the hidden object, however to keep it short, we assume that the hidden object is a perfect electric conductor (for a more detailed analysis see [14]), allowing for simpler results. It is evident that the cloaking shell effectively shrinks our metallic cylinder to the cylinder with the same parameters but with smaller radius, i.e.…”