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Visar resultat 1 - 5 av 35 avhandlingar som matchar ovanstående sökkriterier.

1. 1. Interaction between Electromagnetic Waves and Localized Plasma Oscillations

   Författare :Jan-Ove Hall; Thomas Leyser; Jan Trulsen; Uppsala universitet; []
   Nyckelord :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;

   Sammanfattning : 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). LÄS MER

3. 2. Radio waves in the ionosphere : Propagation, generation and detection

   Författare :Tobia Carozzi; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Astronomy; Astronomi; Astronomy and astrophysics; Astronomi och astrofysik; Space Physics; rymdfysik;

   Sammanfattning : We discuss various topics concerning the propagation, generation, and detec-tionof high-frequency (HF) radio waves in the Earth's ionosphere. With re-gardsto propagation, we derive a full wave Hamiltonian and a polarization evo-lutionequation for electromagnetic waves in a cold, stratified magnetoplasma. LÄS MER

4. 3. HBV frequency multiplier 2D arrays and application

   Författare :Robin Dahlbäck; Chalmers tekniska högskola; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; terahertz sources; 2D array frequency multipliers; Heterostructure Barrier Varactors HBVs ; THz; sub-millimetre waves; THz imaging; varactor frequency multipliers;

   Sammanfattning : The utilisation of the THz spectrum ( 0.3-3 THz ) is hampered by technological difficulties to generate power at these frequencies. LÄS MER

5. 4. VLF and ULF Waves Associated with Magnetospheric Substorms

   Författare :Andrew Collier; Lars Blomberg; James McKenzie; KTH; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Space physics; Subtorms; Magnetosphere; VLF waves; ULF waves; Space physics; Rymdfysik;

   Sammanfattning : A magnetospheric substorm is manifested in a variety of phenomena observed both in space and on the ground. Two electromagnetic signatures are the Substorm Chorus Event (SCE) and Pi2 pulsations. The SCE is a Very Low Frequency (VLF) radio phenomenon observed on the ground after the onset of the substorm expansion phase. LÄS MER

7. 5. Millimetre wave waveguide enclosed grid frequency multipliers and imaging

   Författare :Robin Dahlbäck; Chalmers tekniska högskola; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Millimeter wave; THz imaging; THz sources; Grid; Heterostructure Barrier Var- actors HBVs ; Varactors; Array; FMCW; 2D-grid; Quasi-optical.; Frequency multipliers; Radars; sub-millimetre waves; Schottky diodes;

   Sammanfattning : The utilisation of the THz spectrum ( 0.3-10 THz ) is hampered by fundamental difficulties in generating power at these frequencies. LÄS MER