Stability of active magnetoinductive metamaterials

Abstract

Passive metamaterials suffer from narrow bandwidths and high losses due to limits imposed by causality. Actively loaded metamaterials on the other hand may be designed to overcome these limitations, with the caveat that stability may be difficult to ensure. In this letter, loops with active non-Foster loads, in which resistance, capacitance, and inductance are negative, are arranged in a periodic lattice to form an effective medium with either negative-Re μ or μ-near-zero magnetic properties over a broad range of frequencies. The stability and effective magnetic properties are examined analytically, as well as with numerical simulations. Furthermore, the tradeoffs between stability, bandwidth, and the lower bounds of the permeability are detailed.