Sökning: "extinction theorem"

Hittade 5 avhandlingar innehållade orden extinction theorem.

1. 1. Retrieval of equivalent currents by the use of an integral representation and the extinction theorem --- radome applications

   Författare :Kristin Persson; Institutionen för elektro- och informationsteknik; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; extinction theorem; inverse source problem; integral representation; radome diagnosis; near-field transformation;

   Sammanfattning : The aim of this thesis is to solve an inverse source problem. The approach is based on an integral representation together with the extinction theorem. Both a scalar and a full-wave integral representation are implemented and solved by a Method of Moment procedure. LÄS MER

3. 2. Dispersion Relations in Scattering and Antenna Problems

   Författare :Christian Sohl; Institutionen för elektro- och informationsteknik; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; acoustic and electromagnetic waves; sum rules; scattering and absorption; causality; Herglotz functions;

   Sammanfattning : This dissertation deals with physical bounds on scattering and absorption of acoustic and electromagnetic waves. A general dispersion relation or sum rule for the extinction cross section of such waves is derived from the holomorphic properties of the scattering amplitude in the forward direction. LÄS MER

4. 3. Radome Diagnostics: utilizing Source Reconstruction based on Surface Integral Representations

   Författare :Kristin Persson; Institutionen för elektro- och informationsteknik; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; nondestructive testing; source reconstruction; diagnostics; radome; phase reconstruction; insertion phase delay IPD ; equivalent surface currents;

   Sammanfattning : In this thesis, an inverse source reconstruction method with great potential in radome diagnostics is presented. A radome is a cover that encloses an antenna in order to protect it from environmental influences. LÄS MER

5. 4. Dusty Globules and Globulettes

   Författare :Tiia Grenman; Hans Weber; Erik Elfgren; Kalevi Mattila; Luleå tekniska universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; Applied Physics; Tillämpad fysik;

   Sammanfattning : Interstellar gas and dust can condense into clouds of very different size, ranging from giant molecular cloud complexes to massive, isolated, dark cloudlets, called globules with a few solar masses.This thesis focuses on a new category of small globules, named globulettes. LÄS MER

7. 5. Globulettes : a new class of very small and dense interstellar clouds

   Författare :Tiia Grenman; Luleå tekniska universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Fysik; Fysik;

   Sammanfattning : The space between stars is not empty, but filled with a thin gas and microscopic dust grains, together forming the so-called interstellar medium. Matter is concentrated into clouds of very different sizes, ranging from giant molecular cloud complexes to massive isolated dark small isolated cloudlets, called globules. LÄS MER