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.

A wideband microwave double-negative metamaterial with non-Foster loading

“…The desired condition (L g + L R ) > 0 has the same form as a series combination of a negative inductor with a positive inductor whose resulting inductance remains positive [14]. Non-Foster circuits such as a negative inductor can be designed using negative impedance converters, where recent progress has been made in potential stability issues [14], [15].…”

Noise power in active broadband metamaterials

“…0-dimensional case As proposed in [1], for a periodic medium of magnetically polarizable inclusions with arbitrary loading, an equivalent circuit of N loaded loops is established taking mutual coupling into account as shown in Fig. 1.…”

“…2 (a), respectively. Taking the stability into consideration [1], the NIC load can be defined as R L = −1000Ω and C L = −2pF , while the load inductance is varied from L L = −40nH to L L = −20nH which ranges from the unstable to the stable case. For the purpose of clarity, we use a log-scale PSD with linear-scale frequency.…”

“…Recently the limiting factor associated with active metamaterials, stability, has been investigated by the authors [1,2]. However, the study of their noise performance still remains unexplored.…”

Scattering Characteristics of 2-D Imperfect Cloaks With Layered Isotropic Materials

“…In the analysis of aforementioned cloaks, we assumed that all required materials have broadband permittivities and permeabilities, which may be possible by using active metamaterials [14]. However, in this section, we reevaluate the cloak performance by using passive metamaterials assuming their parameters can be described by the dispersive models, such as the Drude model [6] and the Lorentz model [15].…”