Sökning: "Hawal rashid"

Hittade 2 avhandlingar innehållade orden Hawal rashid.

  1. 1. Improved components for 2SB THz receivers with enhanced sideband rejection performance

    Författare :Hawal Marouf Rashid; Chalmers tekniska högskola; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Thin-film Circuits; S-parameters Measurements; Sideband Separating Receivers; Superconducting Circuits; Millimetre Wave Mixers; Directional Coupler; Terahertz Technology; Waveguide Directional Coupler;

    Sammanfattning : The thesis presents work done in improving the sideband rejection ratio for 2SB cryogenic radio astronomy receivers in general, but more specifically, for the future Onsala 20 m 3-mm receiver system and the ALMA Band 5. In order to attain better than 15 dB sideband rejection ratio over the entire bandwidth (approximately 26% RF fractional bandwidth and one octave the IF bandwidth), it is necessary to improve both RF and IF hybrid assembly to optimum performance, i. LÄS MER

  3. 2. Towards Ultimate Performance of THz Heterodyne Receivers: SIS Frequency Multiplier and Wideband Passive Components

    Författare :Hawal Marouf Rashid; Chalmers tekniska högskola; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; NATURVETENSKAP; NATURAL SCIENCES; Wideband passive components; distributed SIS junction; Frequency multiplier; Frequency up-converter; Hybrids; distributed SIS frequency multiplier;

    Sammanfattning : This thesis focuses on the development of advanced components for the future wideband side band separating and / or multipixel receivers for radio-astronomy with ultimate sensitivity.In this thesis, a novel frequency multiplier based on distributed superconducting tunnel (SIS) junctions has been demonstrated for the first time, taking advantage of the extreme inherent nonlinearity of such device. LÄS MER