Reconfigurable cloak for multiple operating frequencies

An invisible cloak based on active metamaterials whose permittivity can be controlled is proposed, and the performances of the cloak are verified in numerical simulations. Because of the tunability of the active metamaterials, the working frequency of the invisible cloak is reconfigurable, which is different from the traditional cloak designs based on passive metamaterials whose working frequencies are fixed. (c) 2008 American Institute of Physics.