Oblique Incidence Performance of Anisotropic Cylindrical Structures Used for Invisibility Cloak Design

Scattering from anisotropic circular-cylindrical objects is rigorously treated for oblique incidence. The system of coupled differential equations for axial components of electromagnetic field arising in this problem is semi-analytically solved: using modal expansion in the axial and circumferential directions and by applying the finite-difference scheme in the radial direction. Developed analysis method is used to characterize different invisibility cloaks and it is demonstrated that realizable cloaks, which were designed for normal incidence, work properly for incidence angles of up to ±10° away from the normal. For angles greater than ±10° away from the normal the cloak should be redesigned, and for that an efficient design approach is realized by merging the developed program with a global optimization algorithm.