  A general process is proposed to experimentally design anisotropic
inhomogeneous metamaterials obtained through a change of coordinate in the
Helmholtz equation. The method is applied to the case of a cylindrical
transformation that allows to perform cloaking. To approximate such complex
metamaterials we apply results of the theory of homogenization and combine them
with a genetic algorithm. To illustrate the power of our approach, we design
three types of cloaks composed of isotropic concentric layers structured with
three types of perforations: curved rectangles, split rings and crosses. These
cloaks have parameters compatible with existing technology and they mimic the
behavior of the transformed material. Numerical simulations have been performed
to qualitatively and quantitatively study the cloaking efficiency of these
metamaterials.
