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Visar resultat 1 - 5 av 23 avhandlingar som matchar ovanstående sökkriterier.

  1. 1. Limitations on efficiency, size and bandwidth of small antennas

    Författare :Daniel Nyberg; Chalmers tekniska högskola; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; log-periodic antennas; Small antennas; folded dipoles; radiation Q; fundamental limitations; bandwidth;

    Sammanfattning : The allocated space in a mobile phone for the antennas has become smaller and smaller following the size reduction of the mobile phones themselves and the integration of more functions in them. At the same time new communication systems are being planned where such small antennas also need to be wideband (UWB systems) or have multiple ports (MIMO systems). LÄS MER

  3. 2. 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

  4. 3. TDMA for Low Sampling Rate IR-UWB Receivers

    Författare :Muhammad Adeel Ansari; Svante Signell; Ramir Eghbali; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY;

    Sammanfattning : In UWB communication sampling plays a key role in detection of the transmitted data. There are various methods of data transmission and detection at the receiver. Mostly, the detection methods are based on frequency domain methods. LÄS MER

  5. 4. Ultra-wideband feed design and characterization for next generation radio telescopes

    Författare :Jonas Flygare; Chalmers tekniska högskola; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; reflector feed; geodesy; radio astronomy; quad-ridge flared horn; square kilometre array; dielectric loading; spline-defined; decade bandwidth; Ultra-wideband antennas;

    Sammanfattning : Radio telescopes are used as tools for observations in both radio astronomy and geodesy. To observe the weak sources in space, highly sensitive receivers headed by optimized reflector feeds are needed. Wideband and ultra-wideband (UWB) receiver systems enable large continuous frequency bandwidth and reduce the number of receivers that are needed. LÄS MER

  7. 5. Measurement-Based Modeling of Wireless Propagation Channels - MIMO and UWB

    Författare :Johan Kåredal; Institutionen för elektro- och informationsteknik; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; personal area networks; MIMO; channel modeling; Propagation; channel measurements; vehicle-to-vehicle communicationa; ultra-wideband;

    Sammanfattning : Future wireless systems envision higher speeds and more reliable services but at the same time face challenges in terms of bandwidth being a limited resource. Two promising techniques that can provide an increased throughput without requiring additional bandwidth allocation are multiple-input multiple-output (MIMO) systems and ultra-wideband (UWB) systems. LÄS MER