Where Is Waldo? [Microwave Surfing]

Professor Pendry\´s (Imperial College, London) observation [1] from 2006 is an example of the excitement in the electromagnetic research community on the potential of metamaterials to create the equivalent of Harry Potter\´s invisibility cloak. Back then, a research group at Duke University demonstrated [2] how a twodimensional (2-D) structure composed of ten fiberglass rings covered with subwavelength arrays of copper elements could help "channel" an incident electromagnetic (EM) wave in the microwave frequency range around a copper cylinder, minimizing a scattered signal. Earlier this year, a group at the University of California (UC)¿Berkeley [3] raised the stakes by fabricating the "cloak" using nanotechnology (for the subwavelength elements) so that the target could be made to "disappear" at wavelengths approaching the visible spectrum. Exciting as these metamaterial-based developments have been, they remain far from real-life applications. A recent report in The Economist [4] discusses what is achievable in practice using the current hide-and-seek military technology. Here are some highlights from the report [4].