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Träfflista för sökning "WFRF:(Vassilev Vessen 1969) ;pers:(Billade Bhushan 1982)"

Sökning: WFRF:(Vassilev Vessen 1969) > Billade Bhushan 1982

  • Resultat 1-4 av 4
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1.
  • Belitsky, Victor, 1955, et al. (författare)
  • Terahertz Instrumentation For Radio Astronomy
  • 2009
  • Ingår i: International Symposium on Terahertz Science and Technology between Japan and Sweden. ; , s. 28-29
  • Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
    • Radio Astronomy was always a frontrunner in the demand on terahertz technology. Millimetre and sub-millimetre wave receivers operate at ground-based observatories for more than 20 years with real Terahertz instruments making its way to ground-based [1] and space-based observatories, e.g., Herschel HIFI, during last years.In this talk, we will look at the key requirements to the radio astronomy and environmental science terahertz receivers using heterodyne technology. The most promising and established technologies for high-resolution spectroscopy instrumentation will be discussed. Using results of the Group for Advanced Receiver Development for Onsala Space Observatory 20 m telescope, for Atacama Pathfinder Experiment (APEX) telescope and ALMA Project Band 5, we will illustrate the trends and achievements in the terahertz instrumentation for radio astronomy.
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2.
  • Billade, Bhushan, 1982, et al. (författare)
  • ALMA Band 5 (163-211 GHz) Sideband Separating Mixer Design
  • 2008
  • Ingår i: in Proceedings of The 19th International Symposium on Space Terahertz Technology, Groningen, 28-30 April 2008, ed. W. Wild, Space Research Organization of the Netherlands (SRON). ; part I, s. 250-252
  • Konferensbidrag (refereegranskat)
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3.
  • Billade, Bhushan, 1982, et al. (författare)
  • ALMA Band 5 (163-211 GHz) sideband separation mixer design
  • 2008
  • Ingår i: Proceedings of the 19th International Symposium on Space Terahertz Technology, ISSTT 2008. ; , s. 231-233
  • Konferensbidrag (refereegranskat)abstract
    • We present the design of ALMA Band 5 sideband separation mixer based on Niobium superconducting SIS junctions and first experimental results for the double side band mixer. In this mixer the LO injection circuitry is integrated on the mixer substrate using a microstrip line directional coupler with slot-line branches in the ground plane. The isolated port of the LO coupler is terminated by a wideband floating elliptical termination. The mixer employs two SIS junctions with junction area of 3 ?m2 each, in twin junction configuration, followed by a quarter wave transformer to couple it to the RF probe. First measurements of the DSB mixer show promising results with noise temperature around 35K over the entire band.
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4.
  • Forkman, Peter, 1959, et al. (författare)
  • A compact receiver system for simultaneous measurements of mesospheric CO and O3
  • 2016
  • Ingår i: Geoscientific Instrumentation, Methods and Data Systems. - : Copernicus GmbH. - 2193-0856 .- 2193-0864. ; 2016:5, s. 27-44
  • Tidskriftsartikel (refereegranskat)abstract
    • During the last decades, ground-based microwave radiometry has matured into an established remote sensing technique for measuring vertical profiles of a number of gases in the stratosphere and the mesosphere. Microwave radiometry is the only ground-based technique that can provide vertical profiles of gases in the upper stratosphere and mesosphere both day and night, and even during cloudy conditions. Except for microwave instruments placed at high-altitude sites, or at sites with dry atmospheric conditions, only molecules with significant emission lines below 150 GHz, such as CO, H2O, and O3, can be observed. Vertical profiles of these molecules can give important information about chemistry and dynamics in the middle atmosphere. Today these measurements are performed at relatively few sites; more simple and reliable instrument solutions are required to make the measurement technique more widely spread. This need is urgent today as the number of satellite sensors observing the middle atmosphere is about to decrease drastically. In this study a compact double-sideband frequency-switched radiometer system for simultaneous observations of mesospheric CO at 115.27 GHz and O3 at 110.84 GHz is presented. The radiometer, its calibration scheme, and its observation method are presented. The retrieval procedure, including compensation of the different tropospheric attenuations at the two frequencies and error characterization, are also described. The first measurement series from October 2014 until April 2015 taken at the Onsala Space Observatory, OSO (57° N, 12° E), is analysed. The retrieved vertical profiles are compared with co-located CO and O3 data from the MLS instrument on the Aura satellite. The data sets from the instruments agree well with each other. The main differences are the higher OSO volume mixing ratios of O3 in the upper mesosphere during the winter nights and the higher OSO volume mixing ratios of CO in the mesosphere during the winter. The low bias of mesospheric winter values of CO from MLS compared to ground-based instruments was reported earlier.
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  • Resultat 1-4 av 4

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