An architecture for active metamaterial particles and experimental validation at RF

We describe a class of metamaterial particle that employs active elemenis to overcome the inherent limitations of their possive counterparts, such as significant losses, high dispersion, and narrow bandwidth. The active unit cell can be designed to have either an electric or magnetic response. For a magnetic active metamaterial, we derive the design equations for the unit cell and validate them experimentally, through the extraction of effective permittivity and permeability from S-parameter measurements of a unit cell in a waveguide. We show that phase delay in the aniplifier can be used to control losses and dispersion. (c) 2007 Wiley periodicals, Inc.