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Träfflista för sökning "LAR1:lu ;pers:(Gustafsson Mats);pers:(Bernland Anders)"

Sökning: LAR1:lu > Gustafsson Mats > Bernland Anders

  • Resultat 1-10 av 17
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1.
  • Bernland, Anders, et al. (författare)
  • Estimation of Spherical Wave Coefficients from 3D Positioner Channel Measurements
  • 2012
  • Ingår i: IEEE Antennas and Wireless Propagation Letters. - 1548-5757. ; 11, s. 608-611
  • Tidskriftsartikel (refereegranskat)abstract
    • Electromagnetic vector spherical waves have been used recently to model antenna-channel interaction and the available degrees of freedom in MIMO systems. However, there are no previous accounts of a method to estimate spherical wave coefficients from channel measurements. One approach for this, using a 3D positioner, is presented and analyzed in this letter. Measurement results are presented and discussed. It is concluded that estimates based on randomly positioned measurements within a volume are less sensitive to noise than those based only on measurements on the surface.
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2.
  • Bernland, Anders, et al. (författare)
  • Estimation of Spherical Wave Coefficients from 3D Positioner Channel Measurements
  • 2012
  • Rapport (övrigt vetenskapligt/konstnärligt)abstract
    • Electromagnetic vector spherical waves have been used recently to model antenna channel interaction and the available degrees of freedom in MIMO systems. However, there are no previous accounts of a method to estimate spherical wave coefficients from channel measurements. One approach, using a 3D positioner, is presented in this letter, both in theory and practice. Measurement results are presented and discussed. One conclusion is that using randomly positioned measurements within a volume is less sensitive to noise than using only measurements on the surface.
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4.
  • Bernland, Anders, et al. (författare)
  • Physical limitations on the scattering of electromagnetic vector spherical waves
  • 2010
  • Rapport (övrigt vetenskapligt/konstnärligt)abstract
    • Understanding the interaction between electromagnetic waves and matter is vital in applications ranging from classical optics to antenna theory. This paper derives physical limitations on the scattering of electromagnetic vector spherical waves. The assumptions made are that the heterogeneous scatterer is passive, and has constitutive relations which are on convolution form in the time domain and anisotropic in the static limit. The resulting bounds limit the reflection coefficient of the modes over a frequency interval, and can thus be interpreted as limitations on the absorption of power from a single mode. They can be used within a wide range of applications, and are particularly useful for electrically small scatterers. The derivation follows a general approach to derive sum rules and physical limitations on passive systems on convolution form. The time domain versions of the vector spherical waves are used to describe the passivity of the scatterer, and a set of integral identities for Herglotz functions are applied to derive sum rules from which the physical limitations follow.
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5.
  • Bernland, Anders, et al. (författare)
  • Sum rules and constraints on passive systems
  • 2011
  • Ingår i: Journal of Physics A: Mathematical and Theoretical. - : IOP Publishing. - 1751-8113 .- 1751-8121. ; 44:14
  • Tidskriftsartikel (refereegranskat)abstract
    • A passive system is one that cannot produce energy, a property that naturally poses constraints on the system. A system in convolution form is fully described by its transfer function, and the class of Herglotz functions, holomorphic functions mapping the open upper half plane to the closed upper half plane, is closely related to the transfer functions of passive systems. Following a well-known representation theorem, Herglotz functions can be represented by means of positive measures on the real line. This fact is exploited in this paper in order to rigorously prove a set of integral identities for Herglotz functions that relate weighted integrals of the function to its asymptotic expansions at the origin and infinity. The integral identities are the core of a general approach introduced here to derive sum rules and physical limitations on various passive physical systems. Although similar approaches have previously been applied to a wide range of specific applications, this paper is the first to deliver a general procedure together with the necessary proofs. This procedure is described thoroughly, and exemplified with examples from electromagnetic theory.
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6.
  • Bernland, Anders, et al. (författare)
  • Sum rules and constraints on passive systems
  • 2010
  • Rapport (övrigt vetenskapligt/konstnärligt)abstract
    • A passive system is one that cannot produce energy, a property that naturally poses constraints on the system. A system on convolution form is fully described by its transfer function, and the class of Herglotz functions, holomorphic functions mapping the open upper half plane to the closed upper half plane, is closely related to the transfer functions of passive systems. Following a well-known representation theorem, Herglotz functions can be represented by means of positive measures on the real line. This fact is exploited in this paper in order to rigorously prove a set of integral identities for Herglotz functions that relate weighted integrals of the function to its asymptotic expansions at the origin and infinity. The integral identities are the core of a general approach introduced here to derive sum rules and physical limitations on various passive physical systems. Although similar approaches have previously been applied to a wide range of specific applications, this paper is the first to deliver a general procedure together with the necessary proofs. This procedure is described thoroughly, and exemplified with examples from electromagnetic theory.
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7.
  • Bernland, Anders, et al. (författare)
  • Sum rules and constraints on passive systems with applications in electromagnetics
  • 2010
  • Ingår i: [Host publication title missing]. ; , s. 33-36
  • Konferensbidrag (refereegranskat)abstract
    • A passive system is one that cannot produce energy, a property that naturally poses constraints on the system. In this paper there is a review of some results on linear, time translational invariant, continuous, causal and passive systems, where it turns out that Herglotz functions are related to the Fourier transform of the impulse response of such systems. Some well known facts of this function class is considered, and a set of integral identities and an outline of the proof of these are presented. The identities may be used to derive sum rules and constraints on various physical systems. The theory is illuminated with two examples from electromagnetics: the first revisits Fano’s matching equations, while the latter makes a link to the Kramers-Kronig relations and discusses physical limitations on metamaterials.
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8.
  • Bernland, Anders, et al. (författare)
  • Summation rules and physical bounds for partial wave scattering in electromagnetics
  • 2009
  • Ingår i: [Host publication title missing]. ; , s. 206-207
  • Konferensbidrag (refereegranskat)abstract
    • A general approach to derive summation rules in electromagnetics using Herglotz functions is presented in this paper. This approach is then used to obtain summation rules and bounds on partial wave scattering, which are illustrated numerically by the scattering of a Drude sphere.
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10.
  • Gustafsson, Mats, et al. (författare)
  • An overview of some recent physical bounds in scattering and antenna theory
  • 2009
  • Ingår i: ; , s. 1715-1718
  • Konferensbidrag (refereegranskat)abstract
    • The objective of this paper is to give an overview of some recently developed sum rules and physical bounds in scattering and antenna theory. The sum rules are based on integral identities for Herglotz functions that relate the quantity of interest with its low and high-frequency behavior. The sum rules are transformed to bounds by estimating the integrals and applying variational results to the parameters that appear in the asymptotic expansions. The theoretical findings are exemplified by numerical results for various scattering and antenna configurations.
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  • Resultat 1-10 av 17

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