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Sökning: LAR1:lu > Gustafsson Mats > Sjöberg Daniel

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  • Gustafsson, Mats, et al. (författare)
  • An overview of some recent physical bounds in scattering and antenna theory
  • 2009
  • Ingår i: 3rd European Conference on Antennas and Propagation. ; s. 1795-1798
  • 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.
3.
  • Gustafsson, Mats, et al. (författare)
  • Constraints on the temporal dispersion of passive metamaterials
  • 2011
  • Konferensbidrag (refereegranskat)abstract
    • Metamaterial applications such as cloaking, perfect lenses, and artificial permeability are restricted by the frequency dependence of the permittivity, permeability, and index of refraction. Here, causality and passivity together with integral identities for Herglotz functions are used to construct sum rules. The sum rules relate the frequency dependence of the material parameters with their high- and low-frequency values. The corresponding physical bounds determine the minimum variations of the material parameters over a frequency interval. The results are illustrated with a numerical example for artificial permeability.
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5.
  • Gustafsson, Mats, et al. (författare)
  • On the radiation resistance for small capacitive dipole antennas
  • 2011
  • Konferensbidrag (refereegranskat)abstract
    • A relation between the radiation resistance and the quasi-static polarizability, input capacitance, and input inductance for small electric dipole antennas is investigated. The relation follows from the forward scattering sum rule and sum rules for the input impedance together with resonance models for the partial realized gain and the reflection coefficient.
6.
  • Gustafsson, Mats, et al. (författare)
  • Optical theorem and forward scattering sum rule for periodic structures
  • 2011
  • Rapport (övrigt vetenskapligt)abstract
    • Based on energy conservation, an optical theorem is constructed for a slab having an arbitrary periodic microstructure in a plane. A sum rule for low pass structures is derived using analytic properties of Herglotz functions based on causality and passivity. The sum rule relates the extinction cross section to the static polarizability per unit cell, and quantifies the interaction between the slab and electromagnetic fields possible over all wavelengths. The results are illustrated with several numerical and experimental examples.
7.
  • Gustafsson, Mats, et al. (författare)
  • Optical theorem and forward scattering sum rule for periodic structures
  • 2012
  • Ingår i: IEEE Transactions on Antennas and Propagation. - 0018-926X. ; 60:8, s. 3818-3826
  • Tidskriftsartikel (refereegranskat)abstract
    • Based on energy conservation, an optical theorem is constructed for a slab having an arbitrary periodic microstructure in a plane. A sum rule for low pass structures is derived using analytic properties of Herglotz functions based on causality and passivity. The sum rule relates the total cross section to the static polarizability per unit cell, and quantifies the interaction between the slab and electromagnetic fields possible over all wavelengths. The results are illustrated with several numerical and experimental examples.
8.
  • Gustafsson, Mats, et al. (författare)
  • Physical bounds and sum rules for high-impedance surfaces
  • 2010
  • Rapport (övrigt vetenskapligt)abstract
    • High-impedance surfaces are artificial surfaces synthesized from periodic structures. The high impedance is useful as it does not short circuit electric currents and reflects electric fields without phase shift. Here, a sum rule is presented that relates frequency intervals having high impedance with the thickness of the structure. The sum rule is used to derive physical bounds on the bandwidth for high-impedance surfaces. Numerical examples are used to illustrate the result, and show that the physical bounds are tight.
9.
10.
  • Gustafsson, Mats, et al. (författare)
  • Physical bounds and sum rules in scattering and antenna theory
  • 2009
  • Ingår i: Electromagnetics in Advanced Applications, 2009. ICEAA '09. International Conference on. ; s. 600-603
  • Konferensbidrag (refereegranskat)abstract
    • The objective of this paper is to review some recently developed sum rules and physical bounds in scattering and antenna theory. The sum rules are based on identities for Herglotz functions that relate the quantity of interest integrated over all wavelengths with its static polarizability dyadics. They are transformed to physical bounds by applying variational principles for the polarizability dyadics together with various estimates of the integrals. The theoretical findings are exemplified by numerical results for several configurations.
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  • Resultat 1-10 av 31
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