Sökning: "Antenna performance"

Visar resultat 16 - 20 av 247 avhandlingar innehållade orden Antenna performance.

  1. 16. On MIMO Systems and Adaptive Arrays for Wireless Communication : Analysis and Practical Aspects

    Författare :Mattias Wennström; Michael A. Jensen; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Systemteknik; antenna array; calibration; MIMO system; flat fading; non-linear amplifier; switched parasitic antenna; analog beamformer; adaptive antenna testbed; Systemteknik; Systems engineering; Systemteknik; Signal Processing; signalbehandling;

    Sammanfattning : This thesis is concerned with the use of multiple antenna elements in wireless communication over frequency non-selective radio channels. Both measurement results and theoretical analysis are presented. New transmit strategies are derived and compared to existing transmit strategies, such as beamforming and space-time block coding (STBC). LÄS MER

  3. 17. Performance Guarantees for Physical Layer Authentication in Mission-Critical Communications

    Författare :Henrik Forssell; Ragnar Thobaben; Stefano Tomasin; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Physical layer authentication; mission-critical communica- tions; worst-case performance; queueing delay performance; stochastic net- work calculus; optimal attack strategies.; Electrical Engineering; Elektro- och systemteknik;

    Sammanfattning : As the application areas for wireless communications are expanding, we also see new security vulnerabilities arise due to the open nature of the wire- less medium. One particularly challenging problem is how to guarantee the security of emerging mission-critical communications, e.g. LÄS MER

  4. 18. NbN and NbTiN Hot Electron Bolometer THz Mixers

    Författare :Pourya Khosropanah; Chalmers tekniska högskola; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; receiver noise; hot electron bolometer; superconducting detector; spiral antenna; NbTiN; submillimeter mixer; THz mixer; HEB; FTS; NbN; quasioptical receiver; heterodyne receiver; double slot antenna; twin slot antenna; Fourier Transform Spectrometer;

    Sammanfattning : The thesis reports the development of Hot Electron Bolometer (HEB) mixers for radio astronomy heterodyne receivers in THz frequency range. Part of this work is the fabrication of HEB devices, which are based on NbN or NbTiN superconducting thin films (≤5 nm). They are integrated with wideband spiral or double-slot planar antennas. LÄS MER

  5. 19. Ultra-wideband Antenna and Radio Front-end Systems

    Författare :Magnus Karlsson; Anders Rydberg; Linköpings universitet; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Wireless communication; ultra-wideband; radio communication; UWB bandwidth; antenna parallelism; Electrical engineering; Elektroteknik;

    Sammanfattning : The number of wireless communication applications increase steadily, leading to the competition for currently allocated frequency bands. Pressure on authorities around the world to permit communications in higher and wider frequency ranges to achieve higher wireless capacity than those existed in the past has resulted in several new specifications. LÄS MER

  7. 20. Antenna Designs Aiming at the Next Generation of Wireless Communication

    Författare :Sadegh Mansouri Moghaddam; Chalmers tekniska högskola; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Phased array antenna; MIMO efficiency; CDF; Millimeter-wave; PoD; OTA; Ultra-Wideband UWB antenna; Tightly-Coupled Dipole Array TCDA .; RIMP; Random-LoS; 5G;

    Sammanfattning : Millimeter-wave (mm-wave) frequencies have drawn large attention, specically for the fifth generation (5G) of wireless communication, due to their capability to provide high data-rates. However, design and characterization of the antenna system in wireless communication will face new challenges when we move up to higher frequency bands. LÄS MER