Homogenization of active transmission-line-based ENZ metamaterials

An active dispersionless ENZ metamaterial, based on periodic loading of a transmission line with non-Foster negative capacitors, has been introduced recently. Direct experimental determination of the equivalent permittivity of homogenized active transmission line might be difficult due to inherent instability of negative capacitors. It is also difficult to develop a realistic model of active negative capacitor, which is a prerequisite for numerical homogenization. As a first step, one can model the active metamaterial as a transmission line periodically loaded with one-port `black boxes´, properties of which are derived from measured scattering parameters of a single negative capacitor. This method is demonstrated in homogenization of the experimental active ENZ metamaterial operating in the lower RF band (20MHz-120 MHz).