Sökning: "optical antennas"

Visar resultat 16 - 20 av 24 avhandlingar innehållade orden optical antennas.

1. 16. Systematic Antenna Design Using the Theory of Characteristic Modes

   Författare :Zachary Miers; Institutionen för elektro- och informationsteknik; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Theory of Characteristic Modes; Antenna Design; Antenna; Characteristic Modes; Computational Electromagnetics; MIMO Systems; MIMO Antenna; MIMO; Mutual Coupling; Mobile Antenna;

   Sammanfattning : The day Faraday moved a magnet in and out of a wire loop and detected the time-varying magnetic field, the first wireless transmitter / receiver system was created and the world was changed forever. However, it took almost fifty years for Heinrich Hertz to use Maxwell's equations and Faraday's insights in his professorship at Karlsruhe to create the first electromagnetic wireless communication system using a spark gap dipole transmitter and a loop antenna-based receiver. LÄS MER

3. 17. Plasmonic Nanostructures for Molecular Spectroscopy

   Författare :Björn Brian; Chalmers tekniska högskola; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; SEF; DNA; EBL; Nanoparticles; rhodamine 6G; biosensors; SERS; fluorescence;

   Sammanfattning : This thesis focuses on the fabrication, characterization and utilization of nanostructures for chemical sensing and optical enhancement processes.Noble metal nanostructures can support localized surface plasmon resonances (LSPRs), which amplify the strength of the electromagnetic field close to the structures. LÄS MER

4. 18. Mathematical Models and Algorithms for Wireless Network Design and Optimization

   Författare :Yuan Li; Institutionen för elektro- och informationsteknik; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; max-min flow; directional antenna; optimization; integer programming; cellular backhaul network design; delay minimization; SINR; compatible set;

   Sammanfattning : Optimization techniques always play an important role in designing high-performance wireless systems. This presented thesis studies a selected set of optimization problems for different kinds of wireless networks, making use of mathematical programming techniques to find optimal solutions and of efficient heuristics to find near-optimal solutions. LÄS MER

5. 19. Optics for Earth Observation Instruments

   Författare :Arvid Hammar; Chalmers tekniska högskola; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; off-axis; free-form mirrors; measurements; stray light; spline horns; THz; reflector optics; satellites; scientific instruments; diamond turning; tolerancing; telescopes;

   Sammanfattning : The optical system is an essential part of every remote sensing instrument used for detecting electromagnetic waves. Careful design, fabrication and characterization is therefore crucial, especially for satellite-borne missions where the possibility of post-launch repairs is highly limited. LÄS MER

7. 20. Submillimeter-Wave Waveguide Frontends by Silicon-on-Insulator Micromachining

   Författare :Adrian Gomez-Torrent; Joachim Oberhammer; Umer Shah; Goutam Chattopadhyay; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; antenna; orthomode transducer; switch; waveguide; radiofrequency; beamforming network; submillimeter-wave; terahertz; silicon micromachining; deep reactive ion etching; silicon on insulator; Electrical Engineering; Elektro- och systemteknik;

   Sammanfattning : This thesis presents novel radiofrequency (RF) frontend components in the submillimeter-wave (sub-mmW) range implemented by silicon micromachining, or deep reactive ion etching (DRIE). DRIE is rapidly becoming a driving technology for the fabrication of waveguide components and systems when approaching the terahertz (THz) frequency range. LÄS MER