A "cloak of invisibility" sounds like the stuff of comic book superheroes. In fact, invisibility cloaks for any type of electromagnetic radiation--even visible light--are something Duke University postdoctoral fellow David Schurig believes are within grasp. Schurig and the professors directing his research--David Smith at Duke and Sir John Pendry at the Imperial College in London--maintain that by the end of 2007, metamaterials will enable an invisibility cloak that works in the microwave range. Further engineering effort will create such cloaks for other types of light, the researchers say. Metamaterials, or engineered composites, substitute macroscopic objects for atoms in a giant crystalline-like lattice, enabling the pitch of passive-component arrays to set the wavelengths affected. The design of these component arrays harks back to the first principles of electronics--simple R-C-L (resistor-capacitor-inductor) circuits. The electromagnetic waves passing through arrays of tiny resistors, capacitors, inductors and other dielectric materials positioned in free space can be bent down any designer-specified path. In 2000, Smith, who was then at the University of California- San Diego, and his colleagues demonstrated a composite metamaterial that used embedded passive resonators to bend microwaves backward. The circuit elements that the team used were based on the theoretical analysis provided by Pendry and his colleagues in London. Schurig recently sat down with technology editor R. Colin Johnson to describe how the cloaking device works, and what EEs can do to turn this science fiction idea into fact.