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Träfflista för sökning "LAR1:lu ;pers:(Gustafsson Mats);pers:(Sjöberg Daniel)"

Sökning: LAR1:lu > Gustafsson Mats > Sjöberg Daniel

  • Resultat 11-20 av 44
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11.
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12.
  • Gustafsson, Mats, et al. (författare)
  • Physical bounds and sum rules for high-impedance surfaces
  • 2010
  • Rapport (övrigt vetenskapligt/konstnärligt)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.
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13.
  • 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, 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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14.
  • Gustafsson, Mats, et al. (författare)
  • Physical bounds on the all-spectrum transmission through periodic arrays
  • 2009
  • Ingår i: Physical Review Letters. - : IOP Publishing. - 1079-7114. ; 87:3, s. 1-34002
  • Tidskriftsartikel (refereegranskat)abstract
    • We show that the blockage in transmission of a screen with a periodic microstructure integrated over all wavelengths is bounded by the static polarizability per unit area of the screen. Physical bounds on the co-polarized transmission coefficient over a wavelength interval are presented using only information from the zero-frequency properties of the microstructure. The theoretical results are compared to and verified by measurements on a screen composed of a large number of split ring resonators printed on a dielectric substrate.
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15.
  • Gustafsson, Mats, et al. (författare)
  • Physical bounds on the partial realized gain
  • 2010
  • Ingår i: [Host publication title missing]. ; , s. 1-6
  • Konferensbidrag (refereegranskat)abstract
    • An antenna identity, derived from the forward scattering sum rule, shows that the partial realized gain of an antenna is related to the polarizability of the antenna structure. The partial realized gain contains the mismatch, directivity, efficiency, and polarization properties of the antenna. The antenna identity expresses how the performance depends on the electrical size and shape of the antenna structure. It is also the starting point for several antenna bounds. In this paper, the identity, its associated physical bounds, and computational aspects of the polarizability dyadics are discussed.
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16.
  • Gustafsson, Mats, et al. (författare)
  • Sum rules and physical bounds in electromagnetic theory
  • 2010
  • Ingår i: [Host publication title missing]. ; , s. 37-40
  • Konferensbidrag (refereegranskat)abstract
    • Sum rules are useful in many branches of physics and engineering as they relate all spectrum parameter values with their asymptotic expansions. Properties of the dynamic response can hence be inferred by the, in many cases much simpler, static response. This has e.g., been used for lossless matching networks, radar absorbers, extinction cross section, partial realized gain of antennas, high-impedance surfaces, transmission cross section, transmission coefficients, and temporal dispersion of metamaterials. Here, several sum rules and their associated physical bounds are reviewed and it is shown that integral identities for Herglotz functions offer a unified approach in deriving them.
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17.
  • Gustafsson, Mats, et al. (författare)
  • Sum rules and physical bounds on passive metamaterials
  • 2010
  • Ingår i: New Journal of Physics. - : IOP Publishing. - 1367-2630. ; 12
  • Tidskriftsartikel (refereegranskat)abstract
    • Frequency dependence of the permittivity and permeability is inevitable in metamaterial applications such as cloaking and perfect lenses. In this paper, Herglotz functions are used as a tool to construct sum rules from which we derive physical bounds suited for metamaterial applications, where the material parameters are often designed to be negative or near zero in the frequency band of interest. Several sum rules are presented that relate the temporal dispersion of the material parameters with the difference between the static and instantaneous parameter values, which are used to give upper bounds on the bandwidth of the application. This substantially advances the understanding of the behavior of metamaterials with extraordinary material parameters, and reveals a beautiful connection between properties in the design band (finite frequencies) and the low- and high-frequency limits.
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18.
  • Gustafsson, Mats, et al. (författare)
  • Sum rules and physical limitations for passive metamaterials
  • 2011
  • Konferensbidrag (refereegranskat)abstract
    • Bandwidth is an important parameter in many metamaterial applications. It has been shown that Herglotz functions and sum rules offer a powerful methodology to analyze the trade-off between bandwidth and design parameters. Here, this approach is described for the temporal dispersion of constitutive relations and high-impedance surfaces.
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19.
  • Helander, Jakob, et al. (författare)
  • 60 GHz imaging of panels for defect detection using planar scanning
  • 2016
  • Ingår i: 2016 IEEE International Symposium on Antennas and Propagation (APSURSI), AP-S 2016. - 9781509028863 ; , s. 1025-1026
  • Konferensbidrag (refereegranskat)abstract
    • This paper presents imaging results of measurements conducted at 60 GHz, using the planar rectangular near-field technique. Utilizing the stated techniques at higher frequencies enables detection of smaller defects, and allows for a small measurement set-up in a laboratory environment. An algorithm based on the Fast Fourier Transform (FFT) has been developed in order to process the data. The paper provides measurement results for an illustrative panel, which show clear detection of the distributed defects. The purpose of this work is to enable processing of recent data from measurements of industrial composite panels.
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20.
  • Helander, Jakob, et al. (författare)
  • Characterization of Millimeter Wave Phased Array Antennas in Mobile Terminal for 5G Mobile System
  • 2015
  • Ingår i: [Host publication title missing]. ; , s. 7-8
  • Konferensbidrag (refereegranskat)abstract
    • This paper presents a characterization method for millimeter wave (mmWave) phased array antennas in the mobile terminal for 5G communication. Arrays of different antenna designs, operating at 28 GHz, are evaluated according to novel characterization methods in this context - the total scan pattern of the phased array and its respective coverage efficiency. The results show the relevance of evaluating antenna array designs according to these characteristics, and illustrate, by introducing pattern diversity through sub-array schemes, that the coverage efficiency can be enhanced.
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  • Resultat 11-20 av 44

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