Sökning: "log-periodic"

Hittade 4 avhandlingar innehållade ordet log-periodic.

  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. Cold-Electron Bolometers fabricated with Direct Write Technology for Microwave Receiver systems

    Författare :Ernst Otto; Chalmers tekniska högskola; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; MEDICIN OCH HÄLSOVETENSKAP; MEDICAL AND HEALTH SCIENCES; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY;

    Sammanfattning : This thesis concerns the development of microwave detector technology for cosmology instruments and THz imaging, including fabrication of SIN tunnel junctions for thermometry and bolometric detectors, and also phase switch circuits as a part of integrated microwave receiver systems. Cold-Electron Bolometers (CEB) based on Superconductor-Insulator-Normal metal (SIN) tunnel junctions have been developed for employment in sub-millimeter astronomical receivers. LÄS MER

  4. 3. EMC barriers : measurement methodologies and model verification

    Författare :Urban Lundgren; Luleå tekniska universitet; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Industrial Electronics; Industriell elektronik;

    Sammanfattning : The subject of Electromagnetic Compatibility (EMC) is introduced. A short overview of the regulatory EMC requirements in Europe and in the United States is presented. An explanation is given why it is important for people in the electronics business to understand the need for EMC regulations. LÄS MER

  5. 4. Design and development of a microwave multifrequency polarimetric scatterometer for biosphere remote sensing

    Författare :Anders Stjernman; Umeå universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Polarimetry; scatterometer; microwave remote sensing; calibration; network analyzer based; S-parameters; scattering matrix;

    Sammanfattning : Microwave radar and radiometer techniques are used to gather crucial information about the earth and its atmosphere. The ERS-1, JERS-1, RadarSAT and NASA’s Mission to Planet Earth projects are designed to study the changing global environment. In all these endeavors, the key instrument is the radar or scatterometer. LÄS MER