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Träfflista för sökning "WFRF:(Nyström Olle 1979 ) "

Sökning: WFRF:(Nyström Olle 1979 )

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11.
  • Billade, Bhushan, 1982, et al. (författare)
  • Performance of the First ALMA Band 5 Production Cartridge
  • 2012
  • Ingår i: IEEE Transactions on Terahertz Science and Technology. - 2156-342X .- 2156-3446. ; 2:2, s. 208-214
  • Tidskriftsartikel (refereegranskat)abstract
    • We present performance of the first ALMA Band 5 production cartridge, covering frequencies from 163 GHz to 211 GHz. ALMA Band 5 is a dual polarization, sideband separation (2SB) receiver based on all Niobium (Nb) Superconductor-Insulator-Superconductor (SIS) tunnel junction mixers, providing 16 GHz of instantaneous RF bandwidth for astronomy observations. The 2SB mixer for each polarization employs a quadrature configuration. The sideband separation occurs at the output of the IF hybrid that has integrated bias-T for biasing the mixers, and is produced using superconducting thin film technology.Experimental verification of the Band 5 cold cartridge performed together with warm cartridge assembly, confirms that the system noise temperature is below 45 K over most of the RF band, which is less than five photon noise (5 hf/k). This is to our knowledge, the best results reported at these frequencies. The measurement of the sideband rejection indicates that the sideband rejection better than 10 dB over 90% of the observational band.
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12.
  • Billade, Bhushan, 1982, et al. (författare)
  • Performance of the first ALMA Band 5 production cartridge
  • 2011
  • Ingår i: Proceedings of the 22nd International Symposium on Space Terahertz Technology, April 26-28th, 2011 - Tucson, Arizona, USA. ; , s. 56-56
  • Konferensbidrag (refereegranskat)abstract
    • We present performance of the first ALMA Band 5 production cartridge, covering RF frequencies from 163 GHz to 211 GHz. ALMA Band 5 is a dual polarization, sideband separation (2SB) receiver based on all Niobium (Nb) SuperconductorInsulator-Superconductor (SIS) tunnel junction mixer, providing 16 GHz of instantaneous RF bandwidth for the astronomy observations. The 2SB mixer for each polarization employs a quadrature layout. The sideband separation occurs at the output of the IF hybrid that has integrated bias-T for biasing the mixers, and is produced using superconducting thin film technology. Experimental verification of the Band 5 cold cartridge performed together with warm cartridge assembly, confirms the system noise temperature below 45 K, less than five quantum noise (5 hf/k) over most of the RF band, which is to our knowledge, the best results at these frequencies. The measurement of the sideband rejection indicates that the sideband rejection better than 10 dB over 90% of the observational band.
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13.
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14.
  • Meledin, Denis, 1974, et al. (författare)
  • APEX Band T2: A 1.25 – 1.39 THz Waveguide Balanced HEB Receiver
  • 2008
  • Ingår i: 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. 162-166
  • Konferensbidrag (refereegranskat)abstract
    • A waveguide 1.25 - 1.39 THz Hot Electron Bolometer (HEB) balanced receiver was successfully developed, characterized and installed at the Atacama Pathfinder EXperiment (APEX) telescope. The receiver employs a quadrature balanced scheme using a waveguide 90-degree 3 dB RF hybrid, HEB mixers and a 180-degree IF hybrid. The HEB mixers are based on ultrathin NbN film deposited on crystalline quartz with a MgO buffer layer. Integrated into the multi-channel APEX facility receiver (SHeFI), the results presented here demonstrate exceptional performance; a receiver noise temperature of 1000 K measured at the telescope at the center of the receiver IF band 2-4 GHz, and at an LO frequency of 1294 GHz. Stability of the receiver is in line with the SIS mixer bands of the SHeFI, and gives a spectroscopic Allan time of more than 200 s at 1382 GHz with a noise bandwidth of 1 MHz.
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15.
  • Nyström, Olle, 1979, et al. (författare)
  • Integrated Setup for THz Receiver Characterization
  • 2010
  • Ingår i: 21st International Symposium on Space Terahertz Technology 2010, ISSTT 2010; Oxford; United Kingdom; 23 March 2010 through 25 March 2010. - 9781617823626 ; , s. P6-4
  • Konferensbidrag (refereegranskat)abstract
    • A highly versatile measurement setup has been built that allows complete characterization of the ALMA Band 5 cartridge. The measurement setup includes all necessary hardware and largely achieves automatic measurements for the system noise and sideband rejection with in-built optimization procedures. The measurement setup additionally comprises measurements of the receiver saturation, phase and amplitude stability, as well as optical beam characterization.
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16.
  • Nyström, Olle, 1979, et al. (författare)
  • Low-Noise Cryogenic Amplifier built using Hybrid MMIC-like / TRL Technique
  • 2008
  • Ingår i: GigaHertz Symposium, March 5-6, 2008, Göteborg.
  • Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
    • HEMT cryogenic low-noise amplifiers are an important part of instrumentation: the amplifiersuse as a front-end for different measurements and as IF amplifiers in heterodyne receivers.During last few years the low-noise limit has reached as low level as approximately 0.5 K/GHzfor GaAs [1] and 0.25 K/GHz for InP HEMT [2]. However, besides electrical performanceimprovement there were not many improvements on mass and dimension side of suchamplifiers as they were built based on standard TRL technology with discrete active andpassive components. Mass and dimensions are also very important for real applications. Whenultimate low-noise performance is placed in focus, pure MMIC technology seems to looseagainst design using discrete components. With this in view, pioneered work by E. F. Lauria,et. al. [3] have successfully demonstrated a design employing MMIC approach while usingdiscrete components and based on a microstrip on Cuflon with lumped bias network.Encouraged by this work, we propose a compact design of a 4-8 GHz cryogenic low noiseamplifier using a combination of standard TRL and lumped element technology to achieveboth ultimate noise performance over the specified band and a very compact size. In ourdesign, the size reduction of the amplifier is realized by selecting an alumina substrate with ahigh dielectric constant, (εr = 9.9), but also by taking advantage of the lumped networks in thematching and bias circuitries. Avoiding quarter wave transformers and instead use a lumpedelement design approach opens up for the possibilities to reach greater bandwidths andsimultaneously obtain a more compact design. In order to make optimum design, we haveperformed extensive simulations. Each amplifier stage has been simulated in Agilent EMDS,3D electromagnetic field simulation package, including the single layer capacitors, and thenimplemented in the ADS circuit simulations as an S-parameter file. Over the 4-8 GHz band, thesimulations predict noise temperature, Taverage 35 dB. The transistors selected for the design are commercial InP HEMT (HRL) chosendue to their excellent noise performance [2], but also for the very low power consumption,which is of great importance at cryogenic temperatures. All the components used in the RFsignalpath and in the bias circuits are mounted with conductive epoxy. Apart from the RFsignalpath, all components are interconnected via bond-wires. Fine tuning is done by adjustingthe length and loop heights of the bond-wires. At the conference we plan to report results ofmeasurement and characterization of the prototype amplifier.REFERENCES:[1] C Risacher, et. al., “Low Noise and Low Power Consumption Cryogenic Amplifiers forOnsala and Apex Telescopes”, Proceedings of Gaas 2004, October 2004, Amsterdam.[2] N. Wadefalk, et. al., “Cryogenic Wide-Band Ultra-Low Noise IF Amplifier Operating atUltra-Low DC-Power”, IEEE Transactions on Microwave Theory and Techniques, vol. MTT-51, no. 6 June 2003.[3] E. F. Lauria, et. al., “A 200-300 GHz SIS Mixer-Preamplifier with 8 GHz IF Bandwidth”,2001 IEEE International Microwave Symposium, Phoenix, AZ, May 2001.
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17.
  • Vassilev, Vessen, 1969, et al. (författare)
  • Design and Characterization of a 211-275 GHz Sideband Separating Mixer for the APEX Telescope
  • 2008
  • Ingår i: IEEE Microwave and Wireless Components Letters. - 1558-1764 .- 1531-1309. ; 18:1, s. 58 - 60
  • Tidskriftsartikel (refereegranskat)abstract
    • We present the final results of the development and characterization of the sideband separating superconductor-insulator-superconductor (SIS) mixer for the APEX telescope band 1 (211-275 GHz).The sideband separation is achieved by using a quadrature scheme where the RF and a local oscillator (LO) power are applied to two identical double sideband SIS mixers. All mixer components, including the LO and RF distribution circuitry, are integrated into a single mixer block. To achieve a compact design we developed a superconducting Lange coupler, based on Nb thin film, which is used as an IF hybrid. Typical single sideband noise temperature of 100˚K and sideband rejection ratio of about 12 dB and are measured.
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18.
  • Gradinarsky, Lubomir, 1970, et al. (författare)
  • A method for detection of powder materials in metallic hollow structures using microwaves
  • 2008
  • Ingår i: Measurement: Journal of the International Measurement Confederation. - : Elsevier BV. - 0263-2241. ; 41:6, s. 637-646
  • Tidskriftsartikel (refereegranskat)abstract
    • This paper presents a method for detection of the presence of small amounts of solids (powders, granules, etc.) inside metallic structures such as process vessels and containers. The method is based on propagation of microwave electromagnetic (EM) energy inside the structures and analysing the complex reflection coefficient Gamma represented by the scattering parameter S-11. 3D EM simulations were used to predict the behaviour of S for structures of rectangular, circular, and conical shapes, contaminated with materials with weak dielectric properties. The suggested method sensitivity and the effects of the material size and its distribution were assessed and results presented of comparisons of simulations and measurements. This paper demonstrates the ability to detect very low levels of contamination, e.g. of the order of 0.01-0.03 parts of a reference vessel's volume of one (e.g. length = 1 cm, width = 0.5 cm, and height = 2 cm) for materials with weak dielectric properties. This sensitivity is even better in terms of volume ratio (contamination/vessel's volume) for structures with bigger volumes and contaminants with stronger dielectric properties e.g. wet powders. The method is fully scalable for vessels with different sizes. Therefore industrial application of the method to physical processing of pharmaceutics, food, agriculture and others is envisioned. (C) 2007 Elsevier Ltd. All rights reserved.
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19.
  • Nilsson, Peter, et al. (författare)
  • Imaging distinct conformational states of amyloid-β fibrils in Alzheimer's disease using novel luminescent probes
  • 2007
  • Ingår i: ACS Chemical Biology. - : American Chemical Society (ACS). - 1554-8929 .- 1554-8937. ; 2:8, s. 553-560
  • Tidskriftsartikel (refereegranskat)abstract
    • Using luminescent conjugated polyelectrolyte probes (LCPs), we demonstrate the possibility to distinguish amyloid-β 1-42 peptide (Aβ1-42) fibril conformations, by analyzing in vitro generated amyloid fibrils of Aβ1-42 formed under quiescent and agitated conditions. LCPs were then shown to resolve such conformational heterogeneity of amyloid deposits in vivo. A diversity of amyloid deposits depending upon morphology and anatomic location was illustrated with LCPs in frozen ex vivo brain sections from a transgenic mouse model (tg-APPswe) of Alzheimer's disease. Comparative LCP fluorescence showed that compact-core plaques of amyloid β precursor protein transgenic mice were composed of rigid dense amyloid. A more abundant form of amyloid plaque displayed morphology of a compact center with a protruding diffuse exterior. Surprisingly, the compact center of these plaques showed disordered conformations of the fibrils, and the exterior was composed of rigid amyloid protruding from the disordered center. This type of plaque appears to grow from more loosely assembled regions toward solidified amyloid tentacles. This work demonstrates how application of LCPs can prove helpful to monitor aggregate structure of in vivo formed amyloid deposits such as architecture, maturity, and origin.
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20.
  • Nyström, Olle, 1979, et al. (författare)
  • A Vector Beam Measurement System for 211-275 GHz
  • 2006
  • Ingår i: Proceedings 17th International Symposium on Space Terahertz Technology, Paris, FRANCE.. ; , s. P2-28
  • Konferensbidrag (refereegranskat)abstract
    • We propose a novel design for a vector measurement system for the characterization of mm-wave receiver optics alignment across the 211-275 GHz band. Previous published work on vector mm and submm beam measurements employs phase-locked loops (PLLs) with Gunn-oscillators and/or multiple frequency sources, [1], [2]. We are developing a measurement set-up without any PLLs and employ the combination of a single frequency source, comb-generator and direct multiplication LO unit. The design takes advantage of different harmonics used to generate the RF and LO signals and to create the desired IF. Importantly, at the same time it allows obtaining a perfect phase-coherence and initial phase-noise cancellation.The signal source is a vector network analyzer (VNA). In the suggested scheme the VNA generates a signal, fsource, which is fed into a comb-generator that generates number of frequencies ∆fsource apart. When fsource is low, this results in a large number of closely spaced, phase-coherent frequencies. Since any selection among the generated frequencies is phase-coherent, any two of them can be used to produce phase-coherent RF and LO signals by filtering and multiplication. As a test source we use a harmonic mixer mounted on a xyz-scanner. Its absolute position with respect to the receiver optics is predefined by means of triangulation system comprising lasers and position sensitive detectors. The IF from the SIS mixer is down-converted using suitable reference from the comb generator to produce an IF equal to fsource. This signal is fed into Port 2 of the VNA and amplitude and phase are measured. The advantage of using comb generator is to have closely spaced frequencies to choose from and therefore ease the production of the desired IF-frequency and obtaining initial-phase-noise cancellation. Most of the phase-noise is cancelled in the down-conversion in the SIS-mixer and the remaining is cancelled in the second down-conversion before the measurements in the VNA. The cancellation of the remaining phase-noise present at IF is obtained by selecting also the LO, for the second down-conversion, from the harmonics generated by the comb-generator.We also propose to use the same measurement set-up for the frequency bands 275-370 GHz and 385-500 GHz. We believe that our system design has the potential to cover all three bands by only replacing two filters and the LO multiplication unit. Scalar beam measurements up to 320 GHz have already demonstrated a dynamic range of about 20 dB with the harmonic mixer as the RF transmitting source [3]. We expect that vector measurements provide even greater dynamic range, indicating that we can push the frequency even higher with this harmonic mixer as the RF comb source. At the moment we are in the assembly phase of the system design and intend to present results from measurements of the Band 1 of the Facility receiver for Atacama Pathfinder EXperiment (APEX) at the time for the Conference.
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  • Resultat 11-20 av 25
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Nyström, Olle, 1979 (24)
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Lapkin, Igor, 1963 (18)
Desmaris, Vincent, 1 ... (16)
Sundin, Erik, 1979 (16)
Meledin, Denis, 1974 (15)
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