CARLOS ANTONIO FRANCA SARTORI

CARLOS ANTONIO FRANCA SARTORI

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Nonlinear metamaterial lenses for inductive power transmission systems using Duffing-resonator based unit cells
2021 - ALMEIDA, JORGE V. de; GU, XIAOQIANG; MOSSO, MARBEY M.; SARTORI, CARLOS A.F.; WU, KE
Metamaterials (MTMs) based on a periodic array of resonant coils have been shown to behave as μ-negative (MNG), enabling the focusing of magnetic flux. The phenomenon has been deployed by designers to boost the efficiency of many inductively coupled systems, such as magnetic resonance imaging, underwater and underground communications, and charging base stations (CBS) for consumer electronics and implanted devices. However, due to their dependency on high-Q unit cells, linear MNG-like MTMs have limited bandwidth, restricting their use in many applications, notably in near-field simultaneous wireless information and power transmission (NF-SWIPT) systems. To improve the tight constraints of the amplitude-bandwidth trade-off of artificial magnetic lenses, this paper presents a theoretical analysis of nonlinear MTMs based on a lattice of Duffing resonators (DRs). Additionally, it introduces a criterium for the quantification and evaluation of the amplitude-bandwidth enhancement. The analytical results are based on a circuit model and further verified by numerical simulations using commercial software. The preliminary findings in this paper open up possibilities for nonlinear MTM lenses and can be applied to enhance the linear amplitude-bandwidth limit.
A parametric study of inductive SWIPT systems assisted by metamaterial using virtual magnetic TL-based channel modeling
2021 - ALMEIDA, JORGE V. de; SILVA, EDUARDO C. da; MOSSO, MARBEY M.; SARTORI, CARLOS A.F.
This paper presents a general methodology based on the description of the inductive channel as virtual magnetic transmission-lines (VMGTLs). In comparison with other existing methods, VMGTL approach presents a better physical insight of the channel behavior since the model correctly preserves the energy flow between the transmitting and receiving coils. Besides that, it facilitates the integration into the analysis of highly nonlinear and dispersive structures such as metamaterial (MTM) lenses. Particularly, the virtual-TL analogy clarifies that the enhancement of the transmission gain between any two coils assisted by MTM is not due to an enhanced coupling between the drivers, as usually claimed, but to the emergence of propagating near-field modes supported by the MTM. This approach, by means of a parametric study, also indicates, for the first time, that MTMs could be employed not only for the increasing of power but also of data transfer due to the emergence of a sub-resonant region of minimum distortion. Nonetheless, since both effects are mutually exclusive, no passive MTM structure could simultaneously improve power and data transmission.
Virtual magnetic TL-based channel modeling of SWIPT systems assisted by MTMs
2020 - ALMEIDA, JORGE V. de; SILVA, EDUARDO C. da; MOSSO, MARBEY M.; SARTORI, CARLOS A.F.
This paper describes a general methodology for the description of inductive power and data transfer based on virtual magnetic transmission-lines (VMGTLs). This approach presents a better physical insight on the channel behavior since the model correctly preserves the energy flow between the transmitting and receiving coils. Particularly, the virtual-TL analogy clarifies the mechanism of transmission gain improvement between any two coils assisted by MTM lenses. Based on the results of this work, these lenses do not enhance the magnetic coupling between the drivers, as usually claimed, but create conditions to propagating near-field modes to increase their power transfer. This approach also reveals that MTMs could be employed not only for the increasing of power transfer but also for enlarging the inductive channel bandwidth.
Mu-negative metamaterials seen as band-limited non-foster impedances in inductive power transmission systems
2019 - ALMEIDA, JORGE V. de; SIQUEIRA, GLAUCIO L.; MOSSO, MARBEY M.; SARTORI, CARLOS A.F.
In the last decade, various works have demonstrated that a class of artificial material called metamaterials (MTM) can synthesize mu-negative (MNG) media capable of evanescent-wave focusing which largely enhances the magnetic coupling between coils, which is the basic mechanism of Inductive Power Transmission (IPT) systems. In the present work, MTM-enhanced coupling in IPT systems is examined through analytical and numerical results, which are validated by experimental data. Adopting a transmission-line (TL) based approach to describe the general MTM-enhanced IPT system, it is evidenced that MNG MTMs can be interpreted as a negative impedance from a circuital point of view.
Modeling of a metamaterial in the FEA of a contactless transcutaneous energy transfer device
2018 - CARVALHO, G.D.; SILVA, V.C.; HAFFNER, F.; SARTORI, C.A.F.; LEBENSZTAJN, L.; KRAHENBUHL, L.
Metamaterials are difficult to deal with in computational electromagnetic modelling, e.g. finite element analysis. The reason is the prohibitive discretization refinement needed to account for their actual electromagnetic field distribution profile, within the frequency range used in contactless energy transfer devices. We propose an approach to simplify the modeling of a metamaterial in finite element simulations and present an analysis of its impact in the evaluation of the magnetic field distribution in the vicinity of the metamaterial.
Mu-negative metamaterials seen as band-limited non-Foster impedances for magnetic coupled systems
2017 - ALMEIDA, JORGE V. de; SIQUEIRA, GLAUCIO L.; MOSSO, MARBEY M.; SARTORI, CARLOS A.F.
In the last decade, various works have demonstrated that a class of artificial material called metamaterials (MTM) can synthesize μ-negative (MNG) media capable of evanescentwave focusing which largely enhances the magnetic coupling between coils, which is the basic mechanism of Inductive Power Transmission (IPT) systems. In the present work, MTM-enhanced coupling in IPT systems is examined through analytical and numerical results, which are validated by experimental data. Adopting a transmissionline based approach to describe the general MTM-enhanced IPT system, it is evidenced that MNG MTMs can be interpreted as a negative impedance from a circuital point of view.
Effects on the antenna’s radiation pattern due to metamaterial-based sub-wavelength insulation
2017 - ALMEIDA, JORGE V. de; SIQUEIRA, GLAUCIO L.; MOSSO, MARBEY M.; SARTORI, CARLOS A.F.
A metamaterial-based insulator is proposed for highly compact MIMO-systems. In previous work, the proposed insulator has been demonstrated to reduce efficiently the coupling at PEC boundaries between two very close antennas on a common ground plane. The present study concentrates on the effects of this insulator on the antenna radiation pattern. The chosen operating frequency is 2.4 GHz considering that it is a usual frequency for many indoor wireless applications. The theoretical results are supported by numerical simulations.
Metamaterial-enhanced coupling seen as non-Foster impedance matching
2016 - ALMEIDA, JORGE V. de; SIQUEIRA, GLAUCIO L.; MOSSO, MARBEY M.; MAIA, MARCO A.G.M.; SARTORI, CARLOS A.F.
Electrically small antennas (ESA) are characterized by high-Q impedances presenting high reactance and low radiation resistance. Since in most wireless power transmission (WPT) applications, such as inductive power transmission (IPT), to use a full-size antenna is neither practical or desired, the system overall efficiency is usually very poor due to the drivers large reactance. In the last decade, various works have demonstrated that a class of artificial material called metamaterials (MTMs) can synthesize munegative (MNG) media capable of evanescent-wave focusing which largely enhances the coupling between ESA. In the present work, MTM-enhanced coupling in IPT systems is examined. Adopting a lumped element approach to describe the general MTM-enhanced IPT system, it is evidenced that MNG media can be interpreted as a negative inductance (a non-Foster reactance) from a circuital point of view. This paper also presents an approach based on energy density to calculate the module of the MNG slab equivalent inductor.
Enhancing the inductive coupling and efficiency of wireless power transmission system by using metamaterials
2014 - NISHIMURA, SARA I.; ALMEIDA, JORGE V. de; VOLLAIRE, CHRISTIAN; SARTORI, CARLOS A.F.; BREARD, ARNAUD; MOREL, FLORENT; KRAHENBUHL, LAURENT