Wideband Artificial Magnetic Conductors Loaded With Non-Foster Negative Inductors

Gregoire, Daniel J.; White, Carson R.; Colburn, J.S.

doi:10.1109/lawp.2011.2181937

Cited by 70 publications

(25 citation statements)

References 10 publications

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“…Hence, these matching methods are appealing for the matching of fundamentally highelectrically small antennas [6]- [12]. In other electromagnetic applications, the bandwidth of artificial magnetic conductors (AMCs), created by electromagnetic bandgap (EBG) structures, can be increased by loading them with non-Foster elements [13], [14]. Moreover, when transmission lines are periodically loaded with series negative inductances or parallel negative capacitances, as first suggested by Poggio and Mayes (for broadband dipole antenna applications) [15], [16], fast low-dispersion transmission lines can be obtained [17].…”

Section: Introductionmentioning

confidence: 99%

Realizing Non-Foster Reactive Elements Using Negative-Group-Delay Networks

Mirzaei

Eleftheriades

2013

IEEE Trans. Microwave Theory Techn.

113

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An intimate relation is established between non-Foster reactive elements and loss-compensated negative-group-delay (NGD) networks. It is shown that any possible network configuration containing a class of non-Foster elements operates as an NGD network. Likewise, it is demonstrated that a loss-compensated NGD network represents a reactive network with a non-Foster behavior. Consequently, these two properties can be intimately linked together and NGD networks can be utilized to implement non-Foster elements, such as negative capacitors and inductors. This result introduces another perspective in realizing non-Foster reactive elements, leading to new designs that are well behaved and more predictable in terms of stability and operation than traditional designs using negative impedance inverters and negative impedance converters. Based on this concept, loss-compensated NGD networks are proposed for realizing high-quality non-Foster reactive elements. Furthermore, entirely passive non-Foster elements with a limited quality ( ) factor are proposed for which the minimum factor and the maximum achievable bandwidth are inversely related. It is shown that the design of non-Foster reactive elements using NGD networks can lead to the realization of standalone unilateral non-Foster reactive elements in a certain bandwidth. Examples of such non-Foster reactive elements and networks are demonstrated experimentally and shown to be stable.Index Terms-Dispersion engineering, negative group delay (NGD), negative group velocity (NGV), non-Foster reactances.

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Section: Introductionmentioning

confidence: 99%

Realizing Non-Foster Reactive Elements Using Negative-Group-Delay Networks

Mirzaei

Eleftheriades

2013

IEEE Trans. Microwave Theory Techn.

113

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“…However, like all metamaterials, AMCs bandwidth is quite limited. In 2011, a group from HRL Laboratories was the first to show that a NF negative inductor can significantly increase the operating bandwidth of an AMC [21]. In this paper, we consider a specific AMC, namely a patch array placed at a distance d above a ground plane.…”

Section: Non-foster Amcmentioning

confidence: 99%

“…On one hand, NF circuits have been successfully used to improve impedance matching of small antennas, by introducing a negative capacitance in the feeding network [13][14][15][16][17][18][19][20]. On the other hand, the number of NF circuits that demonstrated significant metamaterial bandwidth enhancement with a negative inductance is still very limited [20,21], despite many proposals [5][6][7][8]11]. This paper thus focuses only on negative inductance circuits among all nonFoster circuits.…”

Section: Introductionmentioning

confidence: 99%

Negative inductance circuits for metamaterial bandwidth enhancement

et al. 2017

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Abstract. Passive metamaterials have yet to be translated into applications on a large scale due in large part to their limited bandwidth. To overcome this limitation many authors have suggested coupling metamaterials to non-Foster circuits. However, up to now, the number of convincing demonstrations based on non-Foster metamaterials has been very limited. This paper intends to clarify why progress has been so slow, i.e., the fundamental difficulty in making a truly broadband and efficient non-Foster metamaterial. To this end, we consider two families of metamaterials, namely Artificial Magnetic Media and Artificial Magnetic Conductors. In both cases, it turns out that bandwidth enhancement requires negative inductance with almost zero resistance. To estimate bandwidth enhancement with actual non-Foster circuits, we consider two classes of such circuits, namely Linvill and gyrator. The issue of stability being critical, both metamaterial families are studied with equivalent circuits that include advanced models of these non-Foster circuits. Conclusions are different for Artificial Magnetic Media coupled to Linvill circuits and Artificial Magnetic Conductors coupled to gyrator circuits. In the first case, requirements for bandwidth enhancement and stability are very hard to meet simultaneously whereas, in the second case, an adjustment of the transistor gain does significantly increase bandwidth.

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“…The work of Daniel. J. Gregoire et al [4] has yielded surfaces with bandwidths of 0.8 and thickness of 0.0223λ by loading with active negative inductance elements. For usage in wireless power transfer systems, however, it may be difficult to create negative inductors that can synthesize the required large voltages and currents.…”

Section: Introductionmentioning

confidence: 99%

Efficient artificial magnetic conductor shield for wireless power

Lawson

Yates

Mitcheson

2015

2015 IEEE Wireless Power Transfer Conference (WPTC)

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Artificial magnetic conductors (AMC) offer a solution to increasing link efficiency in inductive power transfer (IPT) while reducing magnetic fields outside the air gap. A practical design for an artificial magnetic conductor, suitable for use as a shield for inductive power transfer, is presented. The AMC makes use of a ferrite substrate and lumped capacitor loading. A model of the plane wave behaviour of the structure is compared to simulation and the performance of the AMC compared to other shielding solutions, in an IPT scenario. The plane wave behaviour is found not to provide a good prediction of the AMC behaviour in the IPT scenario. The AMC shield is found to offer the greatest link efficiency, in the IPT scenario.

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Wideband Artificial Magnetic Conductors Loaded With Non-Foster Negative Inductors

Cited by 70 publications

References 10 publications

Realizing Non-Foster Reactive Elements Using Negative-Group-Delay Networks

Realizing Non-Foster Reactive Elements Using Negative-Group-Delay Networks

Negative inductance circuits for metamaterial bandwidth enhancement

Efficient artificial magnetic conductor shield for wireless power

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