On the Generation of Nondiffracting Beams in Extremely Subwavelength Applications

Rodriguez, Erik Saturnino Gamez; Machnoor, Manjunath; Lazzi, Gianluca

doi:10.1109/tap.2017.2734160

Cited by 20 publications

(6 citation statements)

References 27 publications

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“…In addition, an uncalibrated magnetic field probe has been fabricated in order to assess the current distribution in each cell of the standard and homogenizing metasurface; this aspect is required to experimentally verify if the homogenization filtering procedure reveals effective 63 . The realized sensor is made of a small ferrite cylinder around which a wire solenoid is wrapped (Fig.…”

Section: Resultsmentioning

confidence: 99%

“…In any case, the homogenizing metasurface can confer to the WPT system an efficiency level very similar to the standard configuration but with a more robust behavior with respect to the misalignment, confirming the numerical results. In addition, an uncalibrated magnetic field probe has been fabricated in order to assess the current distribution in each cell of the standard and homogenizing metasurface; this aspect is required to experimentally verify if the homogenization filtering procedure reveals effective 63 . The realized sensor is made of a small ferrite cylinder around which a wire solenoid is wrapped (Fig.…”

Section: Analytical Formulationmentioning

confidence: 99%

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Spatial filtering magnetic metasurface for misalignment robustness enhancement in wireless power transfer applications

Lazzoni

Brizi

Monorchio

2023

Sci Rep

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In this paper, we present the design of spatial filtering magnetic metasurfaces to overcome the efficiency decay arising in misaligned resonant inductive Wireless Power Transfer systems. At first, we describe the analytical framework for the control of currents flowing on a finite-size metasurface, avoiding classical truncation effects on the periphery and opportunely manipulating, at the same time, the spatial magnetic field distribution produced by the closely placed RF driving coil. In order to validate the theoretical approach, we conceive a numerical test case consisting of a WPT system operating at 12 MHz. By performing accurate full-wave simulations, we prove that inducing a uniform current in the metasurface results in a more robust WPT system in terms of misalignment with respect to conventional configurations, also including standard metasurfaces. Therefore, while the use of metasurfaces in WPT systems has been already demonstrated to be beneficial in terms of efficiency enhancement, we confirmed that a proper control of the metasurfaces field filtering response can be advantageous also for the misalignment issue. Notably, the free space wavelength at the operating frequency (12 MHz) is 25 m, whereas the proposed metasurface dimensions are only 0.0024λ × 0.0024λ. Despite the extremely reduced dimensions, the spatial magnetic field distribution produced by the closely placed RF driving coil can be nevertheless opportunely manipulated. Finally, experimental measurements conducted on fabricated prototypes validated the numerical results, demonstrating the effectiveness of the proposed approach. These achievements can be particularly helpful in WPT applications where the position of driving and receiving coils frequently changes, as in consumer devices and biomedical implants.

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Section: Resultsmentioning

confidence: 99%

Section: Analytical Formulationmentioning

confidence: 99%

Spatial filtering magnetic metasurface for misalignment robustness enhancement in wireless power transfer applications

Lazzoni

Brizi

Monorchio

2023

Sci Rep

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“…We measured the voltage drop at the end of the probing solenoid, when the probe is positioned above each unit-cell. As a matter of fact, the voltage drop V 2 is proportional to the magnetic field generated by the single unit-cell that is linked by the solenoid area 52 : where is the vacuum relative permeability, H (A/m) is the magnetic field intensity to be measured, is the differential surface element that is perpendicular to the loop, which is used to calculate the flux of the magnetic field through the unit-cell, is the current that produces the magnetic field and induces the voltage in the solenoid. Likewise, the unit-cell magnetic field ( ) is proportional to its circulating current ( ).…”

Section: Resultsmentioning

confidence: 99%

Analysis and design of holographic magnetic metasurfaces in the very near field for sensing applications at quasi-static regime

Falchi

Rotundo

Brizi

et al. 2023

Sci Rep

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In this paper, we present a novel low-frequency sensing solution based on the manipulation of the near-field distribution by employing a passive holographic magnetic metasurface, excited by an active RF coil placed in its reactive region. In particular, the sensing capability is based on the interaction between the magnetic field distribution produced by the radiating system and the magneto-dielectric inhomogeneities eventually present within the material under test. We first start from conceiving the geometrical set-up of the metasurface and its driving RF coil, adopting a low operative frequency (specifically 3 MHz) to consider a quasi-static regime and able to increase the penetration depth within the sample. Afterwards, since the sensing spatial resolution and performance can be modulated by controlling the metasurface properties, the required holographic magnetic field mask, describing the ideal distribution at a specific plane, is designed. Then, the amplitude and phase of currents, flowing in each metasurface unit-cell and required to synthetize the field mask, are determined through an optimization technique. Next, the capacitive loads necessary to accomplish the planned behavior are retrieved, by exploiting the metasurface impedance matrix. Finally, experimental measurements conducted on fabricated prototypes validated the numerical results, confirming the efficacy of the proposed approach to detect inhomogeneities in a medium with a magnetic inclusion in a non-destructive manner. The findings show that holographic magnetic metasurfaces operating in the quasi-static regime can be successfully employed for non-destructive sensing, both in industrial and biomedical fields, despite the extremely low frequencies.

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“…the so-called nondiffracting beams, has attracted much attention for its interesting properties and potential applications. [1][2][3][4][5][6][7][8][9] The best known example of such beams is the Bessel beams, which are the exact solutions of the Helmholtz wave equation in circular cylindrical coordinates and described by Bessel function of the first kind. [10][11][12][13][14][15][16][17] The intensity distributions of these beams exhibit circular symmetry and consist of a series of concentric rings.…”

Section: Introductionmentioning

confidence: 99%

Local dynamical characteristics of Bessel beams upon reflection near the Brewster angle*

Cui¹,

Guo²,

Hui³

et al. 2021

Chinese Phys. B

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We analytically and numerically study the local dynamical characteristics of the Bessel beams reflected from an air—glass interface near the Brewster angle. A Taylor series expansion based on the angular spectrum component is applied to correct the reflection coefficients near the Brewster angle. Using a hybrid angular spectrum representation and vector potential method, the explicit expressions for the electric and magnetic field components of the reflected Bessel beams are derived analytically under paraxial approximation. The local energy, momentum, spin, and orbital angular momentum of the Bessel beams upon reflection near the Brewster angle are examined numerically by utilizing a canonical approach. Numerical simulation results show that the properties of these dynamical quantities for the Bessel beams near Brewster angle incidence change abruptly, and are significantly affected by their topological charge, half-cone angle, and polarization state. The present study has its importance in understanding the dynamical aspects of optical beams with vortex structure and diffraction-free nature during the reflection process.

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On the Generation of Nondiffracting Beams in Extremely Subwavelength Applications

Cited by 20 publications

References 27 publications

Spatial filtering magnetic metasurface for misalignment robustness enhancement in wireless power transfer applications

Spatial filtering magnetic metasurface for misalignment robustness enhancement in wireless power transfer applications

Analysis and design of holographic magnetic metasurfaces in the very near field for sensing applications at quasi-static regime

Local dynamical characteristics of Bessel beams upon reflection near the Brewster angle*

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