Sökning: "Electromagnetic scattering"

Visar resultat 21 - 25 av 94 avhandlingar innehållade orden Electromagnetic scattering.

  1. 21. Efficient Adaptive Algorithms for an Electromagnetic Coefficient Inverse Problem

    Författare :John Bondestam Malmberg; Göteborgs universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; coefficient inverse problem; inverse scattering; Maxwell’s equations; approximate global convergence; finite element method; adaptivity; ; a posteriori error analysis;

    Sammanfattning : This thesis comprises five scientific papers, all of which are focusing on the inverse problem of reconstructing a dielectric permittivity which may vary in space inside a given domain. The data for the reconstruction consist of time-domain observations of the electric field, resulting from a single incident wave, on a part of the boundary of the domain under consideration. LÄS MER

  3. 22. Direct and Inverse Scattering of Electromagnetic Waves in Nonlinear Media

    Författare :Daniel Sjöberg; Institutionen för elektro- och informationsteknik; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY;

    Sammanfattning : Models for materials with nonlinear electromagnetic response are examined. Three simple physical causes for nonlinear behavior are presented: electronic polarization, molecular direction and electrostriction. LÄS MER

  4. 23. Design of Functional Structures and Measurement Techniques for Electromagnetic Waves

    Författare :Johan Lundgren; Teoretisk elektroteknik; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; functional structures; frequency selective structures; polarization selectivity; metasurface; near-field measurements; antenna measurements; scattering measurement; power density; random media;

    Sammanfattning : Electromagnetic fields exist all around us. Through evolution, nature has developed tools to interact and use these fields, where our eyes are a spectacular example. Humans have a long history of developing structures and objects of their own to alter and interact with these fields. LÄS MER

  5. 24. Stealth radomes

    Författare :Sören Poulsen; Institutionen för elektro- och informationsteknik; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Electromagnetic scattering; Dichroic structures; Frequency selective surface; Elektroteknik; FSS; Electrical engineering; Radomes;

    Sammanfattning : This dissertation deals with periodic structures that are used as free-space electromagnetic filters. Two types of periodic structures are treated, namely the so called frequency selective surface (FSS) and the artificial puck plate (APP) structure. LÄS MER

  7. 25. Hybrid Methods for Computational Electromagnetics in Frequency Domain

    Författare :Stefan Hagdahl; Björn Engquist; Lars Pettersson; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Maxwell s equations; Geometrical Theory of Diffraction; Smooth Surface Diffraction; Boundary Element Method; Hybrid methods; Electromagnetic Scattering; Numerical analysis; Numerisk analys;

    Sammanfattning : In this thesis we study hybrid numerical methods to be used in computational electromagnetics. The purpose is to address a wide frequency range relative to a given geometry. We also focus on efficient and robust numerical algorithms for computing the so called Smooth Surface Diffraction predicted by Geometrical Theory of Diffraction (GTD). LÄS MER