| 1. |
- Fridén, Jonas, et al.
(författare)
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Calculation of antenna radiation center using angular momentum
- 2013
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Ingår i: IEEE Transactions on Antennas and Propagation. - 0018-926X. ; 61:12, s. 5923-5930
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Tidskriftsartikel (refereegranskat)abstract
- An algorithm to compute the radiation center of an antenna, using the Spherical wave expansion (SWE) of the far field or the far field directly, is introduced. The method is based on the angular momentum that is uniquely defined for any antenna far field pattern. The radiation center is defined as the phase reference point where the angular momentum is minimized and corresponds to minimizing the phase variations in the antenna far field pattern. In addition, this approach also allows for determination of the current distribution axis.
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| 2. |
- Friden, Jonas, et al.
(författare)
-
Calculation of antenna radiation center using angular momentum
- 2012
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- An algorithm to compute the Radiation Center of an antenna based on the Spherical Wave Expansion is introduced. The method is based on the angular momentum vector that is uniquely defined for any antenna far field pattern. The radiation center is defined as the phase reference point where the angular momentum is minimized and corresponds to minimizing the phase variations in the antenna far field pattern. In addition, this approach also allows for determination of the Current Distribution Axis.
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| 3. |
- Fridén, Jonas, et al.
(författare)
-
Calculation of antenna radiation center using angular momentum
- 2013
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Ingår i: 7th European Conference on Antennas and Propagation (EuCAP), 2013. - 9781467321877 ; , s. 1531-1535
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Konferensbidrag (refereegranskat)abstract
- An algorithm to compute the Radiation center of an antenna based on the Spherical wave expansion is introduced. The method is based on the angular momentum vector that is uniquely defined for any antenna far field pattern. The radiation center is defined as the unique point where the magnitude of the angular momentum is minimized with respect to translations of the far field. This corresponds to minimizing the phase variations in the antenna far field pattern. In addition the Current distribution axis can be determined, corresponding to minimization of the vertical component of angular momentum.
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| 4. |
- Fridén, Jonas, et al.
(författare)
-
Effect of dissipation on the constitutive relations of bi-anisotropic media - the optical response
- 1997
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Ingår i: Electromagnetics. - : Informa UK Limited. - 0272-6343 .- 1532-527X. ; 17:3, s. 251-267, s. 125-128
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Tidskriftsartikel (refereegranskat)abstract
- This paper discusses the restrictions that dissipation forces on the material parameters and responses of bi-anisotropic media. The treatment is a general time domain analysis where six-vector formalism is applied. Energy conditions set limitations on the optical response dyadics and dyadic susceptibility kernels of the material that have to be satisfied regardless the time dependence of the fields. This paper will treat in detail the resulting restrictions for the optical response of bi-anisotropic media. Examples are given for some special cases. Also uniqueness and equivalence aspects of constitutive relations in the time domain are discussed.
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| 5. |
- Fridén, Jonas, et al.
(författare)
-
Effect of dissipation on the constitutive relations of bi-anisotropic media - the optical response
- 1996
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- This paper discusses the restrictions that dissipation forces on the material parameters and responses of bi-anisotropic media. The treatment is a general time domain analysis where six-vector formalism is applied. Energy conditions set limitations on the optical response dyadics and dyadic susceptibility kernels of the material that have to be satisfied regardless the time dependence of the fields. This paper will treat in detail the resulting restrictions for the optical response of bi-anisotropic media. Examples are given for some special cases. Also uniqueness and equivalence aspects of constitutive relations in the time domain are discussed.
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| 6. |
- Fridén, Jonas, et al.
(författare)
-
Transient electromagnetic wave propagation in anisotropic dispersive media
- 1993
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Ingår i: Journal of the Optical Society of America A: Optics and Image Science, and Vision. - 1084-7529. ; 10:12, s. 2618-2627
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Tidskriftsartikel (refereegranskat)abstract
- Transient electromagnetic wave propagation in a stratified, anisotropic, dispersive medium is considered. Specifically, the direct scattering problem is addressed. The dispersive, anisotropic medium is modeled by constitutive relations (a 3 3 matrix-valued susceptibility operator) containing time convolution integrals. In the general case, nine different susceptibility kernels characterize the medium. An incident plane wave impinges obliquely upon a finite slab consisting of a stratified anisotropic medium. The scattered fields are obtained as time convolutions of the incident field with the scattering kernels. The scattering (reflection and transmission) kernels are uniquely determined by the slab and are independent of the incident field. The scattering problem is solved by a wave-splitting technique. Two different methods for determining the scattering kernels are presented: an embedding and a Green's function approach. Explicit analytic expressions of the wave front are given for a special class of media. Some numerical examples illustrate the analysis.
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| 7. |
- Fridén, Jonas, et al.
(författare)
-
Transient Electromagnetic Wave Propagation in Anisotropic Dispersive Media
- 1992
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- In this paper transient electromagnetic wave propagation in a stratified, anisotropic, dispersive medium is considered. Specifically, the direct scattering problem is addressed. The dispersive, anisotropic medium is modeled by constitutive relations (a 3 × 3 matrix-valued susceptibility operator)con taining time convolution integrals. In the general case, nine different susceptibility kernels characterize the medium. An incident plane wave impinges obliquely on a finite slab consisting of a stratified anisotropic medium. The scattered fields are obtained as time convolutions of the incident field with the scattering kernels. The scattering (reflection and transmission)k ernels are uniquely determined by the slab and are independent of the incident field. The scattering problem is solved by a wave splitting technique. Two different methods to determine the scattering kernels are presented; an imbedding and a Green functions approach. Explicit analytic expressions of the wave front are given for a special class of media. Some numerical examples illustrate the analysis.
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| 8. |
- Fridén, Jonas, et al.
(författare)
-
Transient external 3D excitation of a dispersive and anisotropic slab
- 1997
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Ingår i: Inverse Problems. - : IOP Publishing. - 0266-5611 .- 1361-6420. ; 13:3, s. 691-709
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Tidskriftsartikel (refereegranskat)abstract
- Propagation of a transient electromagnetic field in a stratified, dispersive and anisotropic slab, and related direct and inverse problems, are investigated. The field is generated by a transient external three-dimensional (3D) source. The analysis relies on the wave splitting concept and a two-dimensional Fourier transformation in the transverse spatial coordinates. An investigation of the physical properties of the split fields is made. To solve the direct and inverse scattering problems, wave propagators are used. This method is a generalization and a unification of the previously used imbedding and Green functions methods. The wave propagator approach provides an exact solution of the transmission operator. From this solution it is possible to extract the first precursor (the Sommerfeld forerunner). These results also hold for a bi-anisotropic slab. An inverse problem is outlined using reflection and transmission data corresponding to four, two-dimensional Fourier parameters. Due to the stratification of the medium, the inverse Fourier transformation is not needed in the inverse problem.
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| 9. |
- Friden, Jonas, et al.
(författare)
-
Transient External 3D Excitation of a Dispersive and Antisotropic Slab
- 1995
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Propagation of a transient electromagnetic field in a stratified, dispersive and anisotropic slab and related direct and inverse problems are investigated. The field is generated by a transient external 3D source. The analysis relies on the wave splitting concept and a two-dimensional Fourier transformation in the transverse spatial coordinates. An investigation of the physical properties of the split fields is made. To solve the direct and inverse scattering problems, wave propagators are used. This method is a generalization and a unification of the previously used imbedding and Green functions methods. The wave propagator approach provides an exact solution of the transmission operator. From this solution it is possible to extract the first precursor (the Sommerfeld forerunner). These results also hold for a bi-anisotropic slab. An inverse problem is outlined using reflection and transmission data corresponding to four, two-dimensional Fourier parameters. Due to the stratification of the medium, the inverse Fourier transformation is not needed in the inverse problem.
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