Practical realization of broadband reconfigurable non-Foster ENZ /MNZ/DPS metamaterial

Summary form only given. All known passive materials (or metamaterials) that have either negative (ENG, MNG) or less-than-unity (ENZ, MNZ) real parts of permittivity or permeability suffer from inherent narrow operating bandwidth caused by basic energy-dispersion constraints. Recently, it has been shown possible to go around these basic constrains by the use of so-called non-Foster elements (negative capacitors and negative inductors). Typical examples include both 1D and 2D ENZ metamaterials with extremely broad bandwidth varying from four to six octaves (S. Hrabar, I. Krois, et al., Negative capacitor paves the way to ultra-broadband metamaterials´, Applied physics letters. Vol. 99, No. 25, 25403-1-25403-4, December 2011, S. Hrabar, Active non-Foster Metamaterials: From Intriguing Background Physics to Real-world Application, Proceedings on Metamaterials 2012, Sankt Petersburg, 2012, pp. 601-603). All these implementations contain electronic circuits that generate fixed ENZ values of effective permittivity.