Jan 14 2009
At a recent conference, researchers at Fractal Antenna Systems, Inc. disclosed the approach to making metamaterials work over wide bandwidths. Metamaterials, close-packed grids of conducting 'resonators', offer the unusual ability of bending light or other electromagnetic waves in the opposite direction of conventional lenses, and other odd properties. It has been speculated that a new field of applied optics will result from their perfected application, and this includes invisibility curtains, cloaks, and 'super' lenses.
The firm's researchers gave a prescription for how to make metamaterials work over a wideband. Previously, the unusual properties of metamaterials have only worked over a narrow band, or small color range. This limitation makes them impractical for real applications. With the new approach, metamaterials will be able to be designed to work over a broad range of colors or frequencies, with little degradation of the sought out properties.
The firm's approach uses the geometry of self-similar 'fractals' to shape the grid of resonators. The approach also uses a fractal prescription to mesh and interlace the layers.
Nathan Cohen, who presented the talk at the NANOMETA 2009 conference, noted that the approach was not ad-hoc but guided by the physics of how to make wideband radiators. In 1999, Cohen and a colleague published a definitive paper on this 'frequency invariance' that shows how self-similarity is a requirement by nature. In 1995, Cohen also published a paper reporting the invention of 'fractal resonators'. Cohen noted: “The combination of fractal resonators and a fractal arrangement of and in the metamaterial layers is how nature helps us solve the problem of making metamaterials practical over more than just a single color or narrow frequency range”.
The firm holds the basic patent to fractal resonators, and has filed a patent application for the wideband metamaterial approach as a whole. It will release full information on results of a technology demonstrator in the coming weeks.