Sökning: "spherical vector waves"

Visar resultat 1 - 5 av 6 avhandlingar innehållade orden spherical vector waves.

1. 1. On the Antenna-Channel Interactions: A Spherical Vector Wave Expansion Approach

   Författare :Andres Alayon Glazunov; Andreas F. Molisch; Michael A. Jensen; Institutionen för elektro- och informationsteknik; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; antenna-channel interactions; wireless channels; MIMO; Antennas; propagation; spherical vector waves;

   Sammanfattning : The main focus of this thesis is the analysis of the interactions between antennas and channels where electromagnetic fields play a central role. Our goal has been to devise a general framework to enable a clear separation of the properties of the propagation channel from the influence of the antennas at the same time as it provides a common ground for a joint characterization of their properties. LÄS MER

3. 2. Scattering of elastic waves by an anisotropic sphere with application to polycrystalline materials

   Författare :Ata Jafarzadeh; Chalmers tekniska högskola; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Spherical obstacle; Anisotropy; Attenuation; Polycrystalline materials; Effective wave number; T matrix; Phase velocity; Scattering;

   Sammanfattning : Scattering of a plane wave by a single spherical obstacle is the archetype of many scattering problems in various branches of physics. Spherical objects can provide a good approximation for many real objects, and the analytic formulation for a single sphere can be used to investigate wave propagation in more complex structures like particulate composites or grainy materials, which may have applications in non-destructive testing, material characterization, medical ultrasound, etc. LÄS MER

4. 3. Scattering of elastic waves by an anisotropic sphere

   Författare :Ata Jafarzadeh; Chalmers tekniska högskola; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Sphere; T matrix; Effective wave number; Distribution of inclusions; Phase velocity.; Anisotropy; Attenuation; Scattering;

   Sammanfattning : Scattering of a plane wave by a single spherical obstacle is the archetype of many scattering problems in physics and geophysics. Spherical objects can provide a good approximation for many real objects, and the analytic formulation for a single sphere can be used to investigate wave propagation in more complicated structures like particle composites or grainy materials, which may have application in non-destructive testing, material characterization, medical ultrasound, etc. LÄS MER

5. 4. Sum rules and constraints on passive systems - a general approach and applications to electromagnetic scattering

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

   Sammanfattning : Physical processes are often modeled as input-output systems. Many such systems obey passivity, which means that power is dissipated in the process. This thesis deals with the inevitable constraints imposed on physical systems due to passivity. A general approach to derive sum rules and physical limitations on passive systems is presented. LÄS MER

7. 5. Computational Tools for Antenna Analysis and Design

   Författare :Doruk Tayli; Teoretisk elektroteknik; []
   Nyckelord :Antenna theory; Fundamental bounds; method of moments MoM ; Characteristic modes; macro basis functions MBFs ; adaptive cross approximation ACA ; endfire arrays;

   Sammanfattning : Many engineers and scientists prevalently use computational tools in electromagnetics, which is also the predominant case for antennas. The ever-increasing number of applications and technologies that employ antennas create a constant demand to improve and extend existing tools and develop new ones. LÄS MER