Broadband electromagnetic transparency by graded metamaterials: scattering cancellation scheme

The electromagnetic scattering by a radially inhomogeneous isotropic metamaterial sphere whose electric permittivity is described by the lossless graded Drude model is studied according to the generalized Mie theory in full-wave condition. The distribution of electromagnetic field is calculated by solving Maxwell's equations, and the exact analytic solutions are obtained in terms of confluent Heun and hypergeometry functions. This allows us to achieve the full-wave scattering cross section (SCS) analytically. The corresponding numerical analysis indicates that the full-wave SCS can be extremely small over a broad frequency band, representing a broadband electromagnetic transparency. Moreover, the analytic expression of the full-wave SCS also reveals the conditions for achieving the broadband electromagnetic transparency and makes tunable electromagnetic transparency feasible. (C) 2011 Optical Society of America