Fig 5 - uploaded by Adam Steckiewicz
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![The magnetic field norm in [A/m] and the magnetic flux (lines): a) uniform magnetic field distribution when no object nor cloak is present, b) distorted field for the paramagnetic object (R 0 = 10 mm, μ o = 10), c) less distorted field for the object covered by cloak (t m = t c = 0.01R 0 , μ m = 101.5, σ c = 10 6 S/m) at f = 100 kHz, d) no field distortion at f = 1 MHz.](profile/Adam-Steckiewicz-2/publication/351135569/figure/fig5/AS:1021879649308673@1620646502091/The-magnetic-field-norm-in-A-m-and-the-magnetic-flux-lines-a-uniform-magnetic-field.png)
The magnetic field norm in [A/m] and the magnetic flux (lines): a) uniform magnetic field distribution when no object nor cloak is present, b) distorted field for the paramagnetic object (R 0 = 10 mm, μ o = 10), c) less distorted field for the object covered by cloak (t m = t c = 0.01R 0 , μ m = 101.5, σ c = 10 6 S/m) at f = 100 kHz, d) no field distortion at f = 1 MHz.
Source publication
![Fig. 5. The magnetic field norm in [A/m] and the magnetic flux (lines):...](profile/Adam-Steckiewicz-2/publication/351135569/figure/fig5/AS:1021879649308673@1620646502091/The-magnetic-field-norm-in-A-m-and-the-magnetic-flux-lines-a-uniform-magnetic-field_Q320.jpg)
The article presents a design methodology of a thin layer, high-frequency cylindrical invisibility cloak intended for quasi-static magnetic fields. The proposed bilayer structure of a cloaking shell is synthesized using isotropic ferromagnetic and conductive materials. An analytical formula is derived to find the properties of a ferromagnetic layer...
Contexts in source publication
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... evaluate the effectiveness of the cloaking shell and estimate the frequency f h , a field distortion factor was calculated at a point located at a distance r p = 1.25R 0 from a center of the object (Fig. 5) using the ...
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... an inflection point of the frequency spectrum of the field distortion which for presented cases, in logarithmic scale, is an equivalent of 6 dB drop. An exemplary structure illustrates the operating principle of a quasistatic magnetic cloak. The background without any additional elements had a uniform, non-disturbed distribution of magnetic field (Fig. 5a) at any considered frequency. When circular, paramagnetic (μ o = 10) object was located at the center, the magnetic field became visibly distorted (Fig. 5b). After covering the object by the magnetic cloak, at frequencies much below f h the field distribution was similar as in the previous case. However, for higher frequencies the ...
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... structure illustrates the operating principle of a quasistatic magnetic cloak. The background without any additional elements had a uniform, non-disturbed distribution of magnetic field (Fig. 5a) at any considered frequency. When circular, paramagnetic (μ o = 10) object was located at the center, the magnetic field became visibly distorted (Fig. 5b). After covering the object by the magnetic cloak, at frequencies much below f h the field distribution was similar as in the previous case. However, for higher frequencies the distortion was reduced (Fig. 5c) and for frequencies much above f h perfect cloaking was observed (Fig. ...
Context 4
... considered frequency. When circular, paramagnetic (μ o = 10) object was located at the center, the magnetic field became visibly distorted (Fig. 5b). After covering the object by the magnetic cloak, at frequencies much below f h the field distribution was similar as in the previous case. However, for higher frequencies the distortion was reduced (Fig. 5c) and for frequencies much above f h perfect cloaking was observed (Fig. ...
Context 5
... at the center, the magnetic field became visibly distorted (Fig. 5b). After covering the object by the magnetic cloak, at frequencies much below f h the field distribution was similar as in the previous case. However, for higher frequencies the distortion was reduced (Fig. 5c) and for frequencies much above f h perfect cloaking was observed (Fig. ...
Citations
... Due to the development of novel devices such as magnetic cloaks [3,4], concentrators [5,6], enhanced sensors [7] and artificial magnetic wormholes [8], new possibilities appeared. Nowadays one can improve the measurement range of magnetic field probes [9], simultaneously ensure the effective shielding and 'hide' objects [10], absorb power nearly perfectly in the energy harvesting systems [11] and minimize the influence of a device under test and an environment on each other [12]. Many extraordinary metamaterial properties were achieved through their ability to exhibit diamagnetic behavior and also due to anisotropy of the effective permeability and/or permittivity [13]. ...
This paper introduces a novel waveguide intended for the spatial transfer of alternating magnetic fields. Instead of ferromagnetic material, an air core was proposed, while the cladding was realized using anisotropic metamaterial, built of the resonators and a paramagnetic composite. Since prior works regarding magnetic field transfer concentrated on static or high frequency fields, the proposed device complements the range of medium frequencies (several to hundreds of kilohertz). The three-dimensional model of the 50 cm long and 20 cm wide rectangular structure with metamaterial cladding was made in COMSOL and computed using the finite element method. Multi-turn inductors were considered and homogenized by the current sheet approximation, while an optimization solver was used to identify an optimal design of the waveguide. The analysis was made with respect to different resonators and permeability of the paramagnetic material. Additionally, the frequency response of the structure was determined. On these bases, the dependencies of the mean energy density and magnetic field intensity at the output of the waveguide were characterized. It was shown that discussed structure was able to provide an efficient transfer of the magnetic field between two ports. Thus, this device can be used to extend the distance of the wireless power transfer, especially between devices isolated by a thick barrier (e.g., wall), in which the meta-structure may be embodied.
... Due to an ability to exhibit unordinary properties, for instance a zero or negative permittivity and permeability [1][2][3][4] , a potential interest of creating new functional structures had risen. The synthesis of superlenses 5,6 , cloaks [7][8][9] , new types of antennas 2,10 and absorbers [11][12][13] and devices for medical diagnosis 14,15 are some of many considered applications. Recent advances in terahertz metamaterials also show an accelerating progress of tunable metastructures 16,17 , where a resonance wavelength can be tuned using appropriate external fields. ...
The paper presents a homogenization method of the magnetic metamaterials, made of perpendicularly oriented resonators consisting of multi-turn planar coils. A resulting composite, in the form of parallel stripes with metamaterial cells, exhibits extraordinary properties in the medium frequency magnetic field, such as zero permeability. To identify an effective permeability of this metamaterial, two models were presented, i.e., a three-dimensional numerical model with current sheet approximation as well as Lorentz oscillator model, where individual coefficients are based on the lumped circuit parameters and directly related with a geometry of the unit cell. The accuracy of the second approach is improved by taking into account mutual inductances in a metamaterial grid. Then, a comparison is made with numerical model results to show adequacy of the adopted analytical attempt, and properties of this type of metamaterial are discussed. It is shown that discussed metamaterial structure can achieve negative permeability as well as its values, at identical resonant frequency, are dependent on number of turns of the planar coil.
... The analysis of the WPT system can be performed by numerical methods (e.g., FEM, FDTD, FDFD) [38,[42][43][44][45], by the analytical method [27], or experimentally. Each numerical method requires the preparation of an accurate three-dimensional model and the assignment of different boundary conditions. ...
This article presents the results of the proposed numerical and analytical analysis of the Wireless Power Transfer System (WPT). The system consists of a transmitting surface and a receiving surface, where each of them is composed of planar spiral coils. Two WPT systems were analysed (periodic and aperiodic) considering two types of coils (circular and square). In the aperiodic system, the adjacent coils were wound in the opposite direction. The influence of the type of coils, the winding direction, the number of turns, and the distance between the coils on the efficiency of the WPT system was compared. In periodic models, higher efficiency was obtained with circular rather than square coils. The results obtained with both proposed methods were consistent, which confirmed the correctness of the adopted assumptions. In aperiodic models, for a smaller radius of the coil, the efficiency of the system was higher in the square coil models than in the circular coil models. On the other hand, with a larger radius of the coil, the efficiency of the system was comparable regardless of the coil type. When comparing both systems (periodic and aperiodic), for both circular and square coils, aperiodic models show higher efficiency values (the difference is even 57%). The proposed system can be used for simultaneous charging of many sensors (located in, e.g., walls, floors).
... The usage of simpler circuit model renders it possible to easily determine power flow at the design stage or initial analysis of the WPT system. Numerical methods (e.g., FEM, FDTD and FDFD) [35][36][37] allow for the creation of a complex model and determination of the magnetic field distribution. In this typical approach, it is necessary to prepare the 3D model and to impose suitable boundary conditions. ...
In the article, a wireless charging system with the use of periodically arranged planar coils is presented. The efficiency of two wireless power transfer (WPT) systems with different types of inductors, i.e., circular and square planar coils is compared, and two models are proposed: analytical and numerical. With the appropriate selection of a load resistance, it is possible to obtain either the maximum efficiency or the maximum power of a receiver. Therefore, the system is analyzed at two optimum modes of operation: with the maximum possible efficiency and with the highest power transmitted to the load. The analysis of many variants of the proposed wireless power transfer solution was performed. The aim was to check the influence of the geometry of the coils and their type (circular or square) on the efficiency of the system. Changes in the number of turns, the distance between the coils (transmit and receive) as well as frequency are also taken into account. The results obtained from analytical and numerical analysis were consistent; thus, the correctness of the adopted circuit and numerical model (with periodic boundary conditions) was confirmed. The proposed circuit model and the presented numerical approach allow for a quick estimate of the electrical parameters of the wireless power transmission system. The proposed system can be used to charge many receivers, e.g., electrical cars on a parking or several electronic devices. Based on the results, it was found that the square coils provide lower load power and efficiency than compared to circular coils in the entire frequency range and regardless of the analyzed geometry variants. The results and discussion of the multivariate analysis allow for a better understanding of the influence of the coil geometry on the charging effectiveness. They can also be valuable knowledge when designing this type of system.
