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Sökning: WFRF:(Nyström Olle 1979 )

  • Resultat 1-10 av 25
  • [1]23Nästa
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  • Belitsky, Victor, 1955-, et al. (författare)
  • Facility Heterodyne Receiver for the Atacama Pathfinder Experiment Telescope
  • 2007
  • Ingår i: Proceedings of Joint 32nd International Conference on Infrared Millimeter Waves and 15th International conference on Terahertz Electronics, Sept 3-7, 2007, City Hall, Cardiff, Wales, UK. - 1424414303 ; s. 326-328
  • Konferensbidrag (refereegranskat)
  • 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)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.
  • Lapkin, Igor, 1963-, et al. (författare)
  • Optics Design and Verification for the APEX Swedish Heterodyne Facility Instrument (SHeFI)
  • 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. 351-357
  • Konferensbidrag (refereegranskat)abstract
    • We present the design and verification of the receiver optics for the Single-Pixel Heterodyne Facility Instrument (SHFI) of the APEX telescope [1]. The SHFI is designed to cover the frequency band 211 – 1390 GHz in 6 receiver channels. Four of the receiver channels have been designed, installed and characterized: 211-275 GHz (Band 1); 275-370 GHz (Band 2); 385- 500 GHz (Band 3); 1250-1390 GHz (Band T2). The first three bands employ 2SB SIS mixer technology and Band T2 employs HEB mixers in a waveguide balanced mixer configuration. The entire optics design was driven by the receiver position in the telescope Nasmyth cabin “A” (Fig.1) and the aperture limit of Ø150 mm, introduced by the elevation encoder inside the Nasmyth tube A. This layout and the telescope geometry (~ 6 m distance from the focal plane to the Cabin A) lead us to choose a single-pixel configuration and required using intermediate optics with long focal distances. The common optics path, coupling the receivers to the Cassegrain sub-reflector, consists of the three offset ellipsoidal mirrors, M3, M6, M8s, and three flat mirrors, F4, F5, and F7s. The combination M3 and M6 via flat F4, F5, creates a Gaussian telescope, providing frequency-independent re-imaging of the antenna focal plane from the Cassegrain cabin into the Nasmyth cabin A. Switching between channels is achieved by the precision rotating of the active mirror M8s. The mirror M8s in combination with each channel active mirror M10 provides re-imaging of the secondary onto the feed horn aperture of the selected channel. Such a configuration provides frequency independent illumination of the secondary with the edge taper -12dB. The angular position of the flat mirrors F9 is adjustable and gives additional possibility of fine-tuning of the beam alignment from the common optics to every receiver channels. Verification of the optical design through measurements is essential in order to align the beams from the cryostat windows to the common optics to minimize loss in the quasioptical guiding system. In order to verify the design of the cold optics (corrugated horn + M10) in terms of Gaussian beam parameters, a new wideband vector field measurement system was developed [2]. Vector field measurements were performed for band 1, 2, and 3, and scalar measurements were employed for the THz band.
  • Nyström, Olle, 1979-, et al. (författare)
  • Optics Design and Verificatgion for the APEX Swedish Heterodyne Facility Instrument (SHeFI)
  • 2009
  • Ingår i: Journal of Infrared, Millimeter and Terahertz Waves. - 1866-6892. ; 30:7, s. 746-761
  • Tidskriftsartikel (refereegranskat)abstract
    • In this paper, we present the design and verification of the optics of the Swedish Heterodyne Facility Instrument (SHeFI) receiver installed in the Atacama Pathfinder EXperiment (APEX) telescope during spring 2008. SHeFI is located in the Nasmyth instrumentation Cabin A (NCA). The receiver has been designed to have 6 frequency channels, of which four receiver channels have been built, and characterized: 211-275 GHz(Band 1), 275-370 GHz (Band 2), 385-500 GHz (Band 3), and 1250-1390 GHz (Band T2). Bands 1, 2, and T2 are installed at the telescope and are currently in operation. The optical design is driven by the requirement of frequency independent illumination of the secondary with -12 dB edge taper for each frequency channel and the limitation (beam clearance through the Nasmyth tube and the elevation encoder) imposed by the receiver position in the NCA. This paper describes the design approach, optimization, and verification of the optical system, coupling each individual receiving beam to the common optics of the telescope.
  • Vassilev, Vessen, 1969-, et al. (författare)
  • A Swedish heterodyne facility instrument for the APEX telescope
  • 2008
  • Ingår i: Astronomy & Astrophysics. - 0004-6361. ; 490:3, s. 1157-1163
  • Tidskriftsartikel (refereegranskat)abstract
    • In March 2008, the APEX facility instrument was installed on the telescope at the site of Lliano Chajnantor in northern Chile. The main objective of the paper is to introduce the new instrument to the radio astronomical community. It describes the hardware configuration and presents some initial results from the on-sky commissioning. The heterodyne instrument covers frequencies between 211 GHz and 1390 GHz divided into four bands. The first three bands are sideband-separating mixers operating in a single sideband mode and based on superconductor-insulator-superconductor (SIS) tunnel junctions. The fourth band is a hot-electron bolometer, waveguide balanced mixer. All bands are integrated in a closedcycle temperature-stabilized cryostat and are cooled to 4 K. We present results from noise temperature, sideband separation ratios, beam, and stability measurements performed on the telescope as a part of the receiver technical commissioning. Examples of broad extragalactic lines are also included.
  • Belitsky, Victor, 1955-, et al. (författare)
  • Design and performance of ALMA band 5 receiver cartridge
  • 2010
  • Ingår i: 35th International Conference on Infrared Millimeter and Terahertz Waves (IRMMW-THz), 2010. - 978-1-4244-6655-9 ; s. 1-2
  • Konferensbidrag (refereegranskat)abstract
    • ALMA, Atacama Large Millimetre Array, covers the frequency band from 30 GHz to 960 GHz in ten separate frequency bands. We present here the design and performance of the ALMA Band 5 receiver cartridge that covers 163–211 GHz. The Band 5 receiver shows the state-of-the-art performance with the noise temperature below 65K (SSB) and sideband rejection above 12 dB over 80% of the RF band.
  • Belitsky, Victor, 1955-, et al. (författare)
  • Prototype ALMA Band 5 Cartridge:Design and Performance
  • 2009
  • Ingår i: Proceedings of the 20TH INTERNATIONAL SYMPOSIUM ON SPACE TERAHERTZ TECHNOLOGY, Charlottesville, VA, USA, April 20-22, 2009, s. 2-5.
  • Konferensbidrag (refereegranskat)abstract
    • The Atacama Large Millimeter/submillimeter Array (ALMA), an international astronomy facility, is a partnership of East Asia, Europe and North America in cooperation with the Republic of Chile and aims to build an interferometer radio telescope consisting of more than 60 antennas. The instrument is under construction at the Llano de Chajnantor, about 50 km east of San Pedro de Atacama, Chile. This work presents a part of ALMA frontend, the development, design and performance of one of the frequency channels of the ALMA receiver, the Band 5 prototype cartridge for 163 – 211 GHz frequency band.
  • Billade, Bhushan, 1982-, et al. (författare)
  • ALMA band 5 cartridge performance
  • 2010
  • Ingår i: 21st International Symposium on Space Terahertz Technology 2010, ISSTT 2010; Oxford; United Kingdom; 23 March 2010 through 25 March 2010. - 9781617823626
  • Konferensbidrag (refereegranskat)abstract
    • Work presented here concerns the design and performance of the ALMA Band 5 cold cartridge, one of the 10 frequency channels of ALMA project, a radio interferometer under construction at Atacama Desert in Chile. The Band 5 cartridge is a dual polarization receiver with the polarization separation performed by orthomode transducer (OMT) [1]. For each polarization, Band 5 receiver employs sideband rejection (2SB) scheme based on quadrature layout, with SIS mixers covering 163-211 GHz with 4-8 GHz IF. The LO injection circuitry is integrated with mixer chip and is implemented on the same substrate, resulting in a compact 2SB assembly. Amongst the other ALMA bands, the ALMA Band 5 being the lowest frequency band that uses all cold optics, has the largest mirror. Consequently, ALMA Band 5 mirror along with its support structure leaves very little room for placing OMT, mixers and IF subsystems. The constraints put by the size of cold optics and limited cartridge space, required of us to revise the original 2SB design and adopt a design where all the components like OMT, mixer, IF hybrid, isolators and IF amplifier are directly connected to each other without using any co-ax cables in-between. The IF subsystem uses the space between 4 K and 15 K stage of the cartridge and is thermally connected to 4 K stage. Avoiding co-ax cabling required use of custom designed IF hybrid, furthermore, due to limited cooling capacity at 4 K stage, resistive bias circuitry for the mixers is moved to 15 K stage and the IF hybrid along with an integrated bias-T is implemented using superconducting micro-strip lines. The E-probes for both LO and RF waveguide-to-microstrip transitions are placed perpendicular to the wave direction (back-piece configuration). The RF choke at the end of the probes provides a virtual ground for the RF/LO signal, and the choke is DC grounded to the chassis. The on-chip LO injection is done using a microstrip line directional coupler with slot-line branches in the ground plane. The isolated port of the LO coupler is terminated by floating wideband elliptical termination. The mixer employs two SIS junctions with junction area of 3 μm2 each, in twin junction configuration, followed by a quarter wave transformer to couple it to the signal probe. A quarter-wave high impedance line on an extra layer of SiO2 is used to extract the IF by separating from RF [2]. At the conference, we plan to present details of the cartridge design and results of the experimental characterization of the ALMA Band 5 cold cartridge.
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