Sökning: "dispersive effects"

Visar resultat 1 - 5 av 63 avhandlingar innehållade orden dispersive effects.

  1. 1. Nonlinear Characterization of Wideband Microwave Devices and Dispersive Effects in GaN HEMTs

    Författare :Sebastian Gustafsson; Chalmers tekniska högskola; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; large-signal; dispersive effects; electron trapping; thermal coupling; HEMT; GaN; microwave; wideband;

    Sammanfattning : Measurements play a key role in the development of microwave hardware as they allow engineers to test and verify the RF performance on a system, circuit, and component level. Since modern cellular standards employ complex modulation formats with wider signal bandwidths to cope with the growing demand of higher datarates, nonlinear characterization using wideband stimuli is becoming increasingly important. LÄS MER

  3. 2. Buffer Related Dispersive Effects in Microwave GaN HEMTs

    Författare :Johan Bergsten; Chalmers tekniska högskola; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; trapping effects; C-doping; AlGaN GaN interface quality; recessed ohmic contacts; GaN HEMT; buffer design;

    Sammanfattning : In applications such as mobile communication and radar, microwave power generation at high frequency is of utmost importance. The GaN HEMT offers a unique set of properties that makes it suitable for high power amplification at high frequencies. LÄS MER

  4. 3. Quantum Kinetic Theory for Plasmas : spin, exchange, and particle dispersive effects

    Författare :Robin Ekman; Gert Brodin; Jens Zamanian; Bengt Eliasson; Umeå universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; teoretisk fysik; Theoretical Physics;

    Sammanfattning : This thesis is about developing and studying quantum mechanical models of plasmas. Quantum effects can be important at high densities, at low temperatures, and in strong electromagnetic fields, in various laboratory and astrophysical systems. LÄS MER

  5. 4. InP-based photonic crystals : Processing, Material properties and Dispersion effects

    Författare :Audrey Berrier; Srinivasan Anand; Alfred Forchel; KTH; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Photonic crystals; indium phosphide; photonic bandgap; Bloch modes; slow light; dispersion; coupled cavity waveguides; chemically assisted ion beam etching; lag effect; cavities; optical losses; carrier transport; carrier lifetimes; negative refraction; photonic bandstructure; Physics; Fysik;

    Sammanfattning : Photonic crystals (PhCs) are periodic dielectric structures that exhibit a photonic bandgap, i.e., a range of wavelength for which light propagation is forbidden. The special band structure related dispersion properties offer a realm of novel functionalities and interesting physical phenomena. LÄS MER

  7. 5. QED and collective effects in vacuum and plasmas

    Författare :Joakim Lundin; Mattias Marklund; Thomas Heinzl; Umeå universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; QED; quantum electrodynamics; quantum plasmas; quantum vacuum; Plasma physics; Plasmafysik; fysik; Physics;

    Sammanfattning : The theory of quantum electrodynamics (QED) was born out of an attempt to merge Einsteins theory of special relativity and quantum mechanics. Einsteins energy/mass equivalence together with Heisenberg's uncertainty principle allows for particle pairs to be spontaneously created and annihilated in vacuum. LÄS MER