Search for dissertations about: "electromagnetic radiation"

Showing result 21 - 25 of 126 swedish dissertations containing the words electromagnetic radiation.

2. 21. Interaction between Electromagnetic Waves and Localized Plasma Oscillations

   Author : Jan-Ove Hall; Thomas Leyser; Jan Trulsen; Uppsala universitet; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; Space and plasma physics; space physics; plasma physics; radio waves; ionospheric modification; density depleations; field-aligned irregularities; lower hybrid solitary structures; lower hybrid cavities; Z mode waves; magnetosonic waves; scattering; mode conversion; Rymd- och plasmafysik; Space physics; Rymdfysik;

   Abstract : This thesis treats interaction between electromagnetic waves and localized plasma oscillations. Two specific physical systems are considered, namely artificially excited magnetic field-aligned irregularities (striations) and naturally excited lower hybrid solitary structures (LHSS). READ MORE

4. 22. Photonic terahertz-wave generation, radiation and quasioptical integration

   Author : Biddut Kumar Banik; Chalmers tekniska högskola; []
   Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; semiconductor device modelling; semiconductor diodes; III-V semiconductors; Catadioptric lens; imaging; dipole antennas; slot antennas; lens antennas; semiconductor heterojunctions; dielectric loaded antennas; optical mixers; photomixers; near-field imaging; computer aided engineering; indium compounds; millimetre wave imaging; near-field optics; submillimeter wave generation; photodiodes; terahertz sources; millimetre wave generation; submillimetre wave integrated circuits; microwave imaging; uni-travelling-carrier photodiodes;

   Abstract : This thesis deals with the uni-travelling-carrier photodiode (UTC-PD) based photonic generation of terahertz waves, antenna designs for the terahertz radiation and a novelcatadioptric lens for quasioptical integration.The ongoing and accomplished research work on the UTC-PD, its limitations and optimisation scopes for attaining higher bandwidth and higher output power have been discussed. READ MORE

5. 23. Antenna array systems : electromagnetic and signal processing aspects

   Author : Maria Lanne; Chalmers tekniska högskola; []
   Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY;

   Abstract : A simple and commonly used model of an array antenna consists of identical sensors, which are equidistantly located along a line. But in reality the array antennas do not look this way. The elements are not perfectly positioned, and sometimes they are even placed on a curved surface (conformal arrays). READ MORE

6. 24. Electromagnetic modeling using the partial element equivalent circuit method

   Author : Jonas Ekman; Luleå tekniska universitet; []
   Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Industriell elektronik; Industrial Electronics;

   Abstract : This thesis presents contributions within the field of numerical simulations of electromagnetic properties using the Partial Element Equivalent Circuit (PEEC) method. Numerical simulations of electromagnetic properties are of high industrial interest. READ MORE

7. 25. Kinetic modelling of runaway in plasmas

   Author : Ola Embréus; Chalmers tekniska högskola; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; Fokker-Planck equation; synchrotron radiation; plasma; runaway; bremsstrahlung; Boltzmann equation;

   Abstract : The phenomenon of runaway occurs in plasmas in the presence of a strong electric field, which overcomes the collisional friction acting on the charged particles moving through the plasma. A subpopulation of particles can then be accelerated to energies significantly higher than the thermal energy. READ MORE