| 131. |
- Sjöberg, Daniel
(författare)
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Determination of propagation constants and material data from waveguide measurements
- 2009
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Ingår i: Progress In Electromagnetics Research B. - 1937-6472. ; 12, s. 163-182
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents an analysis with the aim of characterizing the electromagnetic properties of an arbitrary linear, bianisotropic material inside a metallic waveguide. The result is that if the number of propagating modes is the same inside and outside the material under test, it is possible to determine the propagation constants of the modes inside the material by using scattering data from two samples with different lengths. Some information can also be obtained on the cross-sectional shape of the modes, but it remains an open question if this information can be used to characterize the material. The method is illustrated by numerical examples, determining the complex permittivity for lossy isotropic and anisotropic materials.
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| 132. |
- Sjöberg, Daniel
(författare)
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Direct and Inverse Scattering of Electromagnetic Waves in Nonlinear Media
- 1999
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Models for materials with nonlinear electromagnetic response are examined. Three simple physical causes for nonlinear behavior are presented: electronic polarization, molecular direction and electrostriction. Some introductory results and approximations for nonlinear, dispersive media are given, such as the phase-matching criterion, Miller's rule, the Born approximation and the slowly varying amplitude approximation. However, the emphasis is on instantaneously reacting media, that is, materials with no or negligible memory. For these models, the inverse scattering problem of determining the field dependent permittivity and permeability from the scattered field is solved.
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| 133. |
- Sjöberg, Daniel
(författare)
-
Dispersive effective material parameters
- 2006
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Ingår i: Microwave and Optical Technology Letters. - : Wiley. - 0895-2477 .- 1098-2760. ; 48:12, s. 2629-2632
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Tidskriftsartikel (refereegranskat)abstract
- The author studied how effective material parameters call be defined for Maxwell's equations when taking dispersion into account. The reasoning is based oil the concept of dispersion relations, and is consequently primarily concerned with lossless media. The author essentially required that the effective material parameters should produce the same dispersion relations as the heterogeneous problem, which implies that the effective material is primarily connected to the phase velocity of the waves. Material parameters that exhibit only temporal dispersion call be defined if the propagation direction is fixed. (c) 2006 Wiley Periodicals, Inc.
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| 134. |
- Sjöberg, Daniel
(författare)
-
Dispersive effective material parameters for Maxwell's equations
- 2006
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- We study how effective material parameters can be defined for Maxwell's equations when taking dispersion into account. The reasoning is based on the concept of dispersion relations, and is consequently primarily concerned with lossless media. We essentially require that the effective material parameters should produce the same dispersion relations as the heterogeneous problem, which implies the effective material is primarily connected to the phase velocity of the waves. Material parameters which exhibit temporal dispersion only, can be defined if the propagation direction is fixed.
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| 135. |
- Sjöberg, Daniel
(författare)
-
Effective material parameters for 3D periodic media with small but non-vanishing microscopic scale
- 2004
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Ingår i: URSI 2004 International Symposium on Electromagnetic Theory. - 8884922526 ; , s. 993-995
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Konferensbidrag (refereegranskat)abstract
- We find effective (homogenized) parameters for Maxwell's equations when the microscopic scale becomes small, but not infinitesimal, compared to the wavelength. The analysis is based on a singular value decomposition of the differential operator in Maxwell's equations
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| 136. |
- Sjöberg, Daniel, et al.
(författare)
-
Electromagnetic Properties of Heterogeneous Material Structures Produced in 3D-Printers
- 2014
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Ingår i: [Host publication title missing]. - 9781479973255 ; , s. 605-607
-
Konferensbidrag (refereegranskat)abstract
- We demonstrate the design, manufacture, and characterization of an X-band waveguide filter using 3D printer technology. The permittivity of the PLA plastic used in the printer is measured to be 2.3 - 0.01j, with about 4% uniaxial anisotropy. The manufactured filter consists of seven dielectric slabs interspace by air. Measured and simulated results agree very well, which shows the possibility of using this relatively inexpensive technology for prototyping advanced electromagnetic designs.
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| 137. |
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| 138. |
- Sjöberg, Daniel
(författare)
-
Exact and asymptotic dispersion relations for homogenization of stratified media with two phases
- 2006
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Ingår i: Journal Electromagnetic Waves and Applications. - : Informa UK Limited. - 1569-3937 .- 0920-5071. ; 20:6, s. 781-792
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Tidskriftsartikel (refereegranskat)abstract
- Using exact dispersion relations for electromagnetic wave propagation in layered, periodic media, consisting of two phases, we derive explicit asymptotic solutions for small wavenumbers. These solutions are compared to the numerical solutions of the exact dispersion relations, and applications to homogenization problems are discussed. The results can be used as test cases for homogenization techniques intended for finite scale homogenization, that is, where the wavelength is not assumed infinitely large compared to the microscale.
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| 139. |
- Sjöberg, Daniel
(författare)
-
Exact and asymptotic dispersion relations for homogenization of stratified media with two phases
- 2005
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Using exact dispersion relations for electromagnetic wave propagation in layered, periodic media, consisting of two phases, we derive explicit asymptotic solutions for small wavenumbers. These solutions are compared to the numerical solutions of the exact dispersion relations, and applications to homogenization problems are discussed. The results can be used as test cases for homogenization techniques intended for finite scale homogenization, that is, where the wavelength is not assumed infinitely large compared to the microscale.
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| 140. |
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