Broadband and low-loss non-resonant metamaterials
Loss and bandwidth have been major problems that limit the potential applications on metamaterials for a long time. To bring the ultimate opportunity to metamaterials, we analyze and discuss, in this chapter, another type of metamaterials that perform at low loss and broad bandwidth. Although the range of structures is limited to those having only electric response, with an electric permittivity always equal to or greater than unity, there are still numerous metamaterial design possibilities enabled by leveraging the non-resonant elements. For example, a gradient, impedance matching layer can be added that drastically reduces the return loss of the optical elements, making them essentially reflectionless and lossless. In microwave experiments, we demonstrate the broadband design concepts with a gradient-index lens and a beam-steering element, both of which are confirmed to operate over the entire X-band (roughly 8-12∈GHz) frequency spectrum. © Springer Science+Business Media, LLC 2010.
