The paper presents the analysis of cylindrical and spherical structures used for invisible cloak realization. Different cylindrical and spherical cloak realizations were analyzed in terms of bistatic scattering cross section. In addition, optimization algorithm was connected with the analysis routine to find the constitutive parameters of the cloak that reduce both backscattering and forward scattering. The results show that it is possible to obtain adequate invisibility performance by covering the PEC sphere with only 2 thin anisotropic layers.