| 1. |
- Abgaryan, Garnik V., et al.
(författare)
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TE-Polarized Electromagnetic Wave Diffraction by a Circular Slotted Cylinder
- 2023
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Ingår i: Mathematics. - : MDPI. - 2227-7390. ; 11:9
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Tidskriftsartikel (refereegranskat)abstract
- The problem of diffraction of a TE-polarized electromagnetic wave by a circular slotted cylinder is investigated. The boundary value problem in question for the Helmholtz equation is reduced to an infinite system of linear algebraic equations of the second kind (SLAE-II) using integral summation identities (ISI). A detailed study of the matrix operator of the problem is performed and its Fredholm property in the weighted Hilbert space of infinite sequences is proven. The convergence of the truncation method constructed in the paper for the numerical solution of SLAE-II is justified and the results of computations are presented and discussed, specifically considering the determination of resonance modes.
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| 2. |
- Alekseev, Gennady, et al.
(författare)
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Optimization approach for axisymmetric electric field cloaking and shielding
- 2021
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Ingår i: Inverse Problems in Science and Engineering. - : Taylor & Francis. - 1741-5977 .- 1741-5985. ; 29:1, s. 40-55
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Tidskriftsartikel (refereegranskat)abstract
- In this paper we study inverse problems of electric conductivity that arise in the design of spherical shielding or cloaking shells and other functional devices used to control static electric fields. The shells are considered consisting of a finite number of layers filled with homogeneous isotropic or anisotropic medium. The inverse problems under study are reduced to control problems with the layers electric conductivities taken as controls. A different choice of minimized functionals allows us to solve a wide range of design problems using one approach. A numerical algorithm to solve these problems is based on particle swarm optimization. Various results of numerical experiments are discussed in order to find the most effective designs. The findings obtained in this study describe a broad set of specific easy-to-manufacture structures that have the highest cloaking or shielding performance in the class of layered shells.
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| 3. |
- Angermann, L., et al.
(författare)
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A nonlinear multiparameter EV problem
- 2018
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Ingår i: Progress In Electromagnetics Research Symposium. - Cham : Springer New York LLC. - 9783319940595 - 9783319940601 ; , s. 55-70
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Konferensbidrag (refereegranskat)abstract
- We investigate a generalization of one-parameter eigenvalue problems arising in the theory of wave propagation in waveguides filled with nonlinear media to more general nonlinear multi-parameter eigenvalue problems for a nonlinear operator. Using an integral equation approach, we derive functional dispersion equations (DEs) whose roots yield the desired eigenvalues. The existence of the roots of DEs is proved and their distribution is described.
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| 4. |
- Angermann, Lutz, et al.
(författare)
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Eigenmodes of linearised problems of scattering and generation of oscillations on cubically polarisable layers
- 2015
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Ingår i: Inverse Problems and Applications. - Cham : Springer-Verlag New York. - 9783319124988 - 9783319124995 ; , s. 67-80
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Konferensbidrag (refereegranskat)abstract
- In the frequency domain, the resonant properties of nonlinear structures are determined by the proximity of the scattering/generation frequencies of the nonlinear structures to the complex eigenfrequencies of the corresponding homogeneous linear spectral problems with the induced nonlinear permeability of the medium. Here the case of cubically polarisable, canalising, and decanalising layers is considered.
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| 5. |
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| 6. |
- Cappello, Barbara, et al.
(författare)
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Analysis of the surface impedance of a sinusoidally modulated metasurface
- 2019
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Ingår i: 2019 International Conference on Electromagnetics in Advanced Applications (ICEAA). - : IEEE. - 9781728105635 ; , s. 0075-0077
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Konferensbidrag (refereegranskat)abstract
- Metasurfaces have been extensively exploited in recent years for mantle cloaking applications. In this type of problems it is of fundamental importance to determine the connection between the metasurface geometrical parameters and the realised value of surface impedance, in order to properly design the metasurface. In this paper the surface impedance of a non homogeneous metasurface, based on a sinusoidally modulated metallic pattern is analysed.
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| 7. |
- Derevyanchuk, E. D., et al.
(författare)
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Reconstruction of Electromagnetic Parameters of a Thin Anisotropic Dielectric Slab
- 2018
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Ingår i: 2018 Progress in Electromagnetics Research Symposium (PIERS-Toyama). - 9784885523151 ; , s. 1968-1972
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Konferensbidrag (refereegranskat)abstract
- Reconstruction of electromagnetic parameters of artificial materials is an urgent problem [1], [2]. In practice, as a rule, these parameters cannot be directly measured. Therefore, methods of mathematical modeling must be applied. Conventional waveguide measurement equipment employs network analyzers and dielectric samples having the simplest shape of a parallelepiped adjusted to the walls of a standard rectangular waveguide. Such setups open the way to use well-developed analytical-numerical techniques [3], [4] of determining permittivity and other parameters of the inclusion using accurate closed-form solutions and asymptotic approximations. This work is a continuation of the series of papers [3], [4] devoted to the analysis of inverse problems of finding permittivity and permeability of layered materials. We apply a specially developed mathematical and numerical technique that combines analytical and numerical approaches providing the results with guaranteed accuracy. Particularly, we develop the methods [3] of determining permittivity and permeability tensors of anisotropic materials in a rectangular waveguide.
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| 8. |
- Derovyanchuk, E. D., et al.
(författare)
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Reconstructing Permittivity and Permeability of Multi-Sectional Anisotropic Diaphragms
- 2018
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Ingår i: 2018 Progress in Electromagnetics Research Symposium (PIERS-Toyama). - 9784885523151 ; , s. 1963-1967
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Konferensbidrag (refereegranskat)abstract
- A great variety of new and artificial materials have been created during the last decades, such as metamaterials, various composites and many others. To analyze and determine the characteristics of such materials advanced mathematical methods are applied. This work is devoted to the developing the technique for reconstruction of electromagnetic parameters of multi-sectional anisotropic diaphragms in a waveguide of rectangular cross section. To solve this inverse problem we make use of the method of rotation applied for anisotropic materials and reconstruct the quantities to be determined, including the diaphragm positions, from the values of the transmission coefficient measured at different frequencies. The efficiency and accuracy of computations are validated in the course of analytical-numerical solution to the inverse problem. The developed techniques and obtained results can be implemented in practical measurements when anisotropic materials and media with unknown properties are investigated with the aid of commonly used waveguide devices and analyzers.
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| 9. |
- Ivanchenko, Igor, et al.
(författare)
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A novel resonance method for determining the complex permittivity of local inclusions in a rectangular waveguide
- 2020
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Ingår i: Measurement science and technology. - : Institute of Physics (IOP). - 0957-0233 .- 1361-6501. ; 31:9
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Tidskriftsartikel (refereegranskat)abstract
- A novel resonance method for determining the complex permittivity of materials in the X-band is proposed. A distinctive feature of this method is that the sample under test, located in a radio-transparent isotropic and homogeneous dielectric matrix, is both a local inclusion and the excitation element of the resonance in the microwave module 'waveguide–dielectric matrix–inclusion'. The complex permittivity of an inclusion is determined by comparing the measured resonance frequency and quality factor with the computed database value. The permittivity and loss factor of microwave ceramics, natural granite and ferrite are investigated, as well as crystals of lead fluoride PbF2 doped with holmium trifluoride HoF3 and erbium fluoride ErF3 of different concentrations. The method allows the permittivity and loss tangent to be determined with uncertainties of 0.1% and 5%, respectively.
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| 10. |
- Ivanchenko, I., et al.
(författare)
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Combined system of the microstrip antennas with different frequencies
- 2016
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Ingår i: 2016 22nd International Conference on Applied Electromagnetics and Communications (ICECOM). - 9789536037711 - 9781509049998
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Konferensbidrag (refereegranskat)abstract
- The combined system with microstrip antennas (f1=1.85GHz; f2=3.7GHz, f3=1.75GHz, f4= 3.5GHz) is presented. The measurements of the prototype characteristics have shown that elevation angle of peak directivity of the antennas is oriented to zenith. Simulated S11 at stated frequencies with the following minimum values of S11 = -34dB, f=1.85GHz; S11=-21dB, f=3.7GHz; S11 = -22dB, f=1.75GHz; S11=-19dB, f=3.5GHz are observed.
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