By Peter Weiss
It might not seem like much compared with Harry Potter’s magic garment, but the first functional invisibility cloak has emerged from a North Carolina laboratory.
The disk of concentric fiberglass-and-copper bands—about the size of a cocktail coaster—bends a narrow-frequency range of microwaves around a protected zone at its center. By then reorienting those electromagnetic rays so that they exit the disk on their original paths, as if undisturbed, the shield renders itself and whatever is in its protected zone almost invisible to a microwave detector downstream.