| 1. |
- Güsten, R., et al.
(författare)
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APEX - The Atacama Pathfinder Experiment
- 2006
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Ingår i: Proceedings of SPIE - The International Society for Optical Engineering. - : SPIE. - 0277-786X .- 1996-756X. ; 6267 I
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Konferensbidrag (refereegranskat)abstract
- APEX, the Atacama Pathfinder Experiment, has been successfully commissioned and is in operation now. This novel submillimeter telescope is located at 5107 m altitude on Llano de Chajnantor in the Chilean High Andes, on what is considered one of the world's outstanding sites for submillimeter astronomy. The primary reflector with 12 m diameter has been carefully adjusted by means of holography. Its surface smoothness of 17-18 μm makes APEX suitable for observations up to 200 μm, through all atmospheric submm windows accessible from the ground.
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| 2. |
- Belitsky, Victor, 1955, et al.
(författare)
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Heterodyne Single-Pixel Facility Instrumentation for APEX Telescope
- 2006
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Ingår i: in "Millimeter and Submillimeter Detectors for Astronomy III", eds. J. Zmuidzinas, W.S. Holland, S. Withington, W.D. Duncan, Proceedings of SPIE. ; 6275, s. 15-
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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| 3. |
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| 4. |
- Belitsky, Victor, 1955, et al.
(författare)
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Superconducting microstrip line models at millimeter and sub-millimeter waves and their comparison
- 2003
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Ingår i: Proceedings of the 14th International Symposium on Space and Terahertz technology. ; , s. 456-475
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Konferensbidrag (refereegranskat)abstract
- Performance of superconductor — insulator - superconductor (SIS) tunnel junction mixers andtheir instantaneous input RF bandwidth are mostly depending on the integrated tunin g circuit used to resonate out SIS junction capacitance; Nb-based SIS mixers operate in the frequency range of about 80 - 1000 GHz and typically use microstrip-based integrated tuning circuitries.One of the major challenges in designing the tuning circuitry for SIS mixers is accuracy of models for superconducting microstrip line (SML). Modeling gives the only tool to solve the problem of designing SML-based circuits because for such high frequencies no direct measurements of a superconducting transmission line can be made with required high accuracy.However, creating an accurate model for such a superconducting transmission line is a challengeby itself. In the SML, produced usually by thin-film technology, the magnetic field penetrationdepth is comparable with the thicknesses of the dielectric and superconductors comprising theline. As a result the electromagnetic wave is propagated not only in the dielectric media but alsoinside the superconducting strip and ground electrodes constituting the SML. This createsdramatic changes in the transmission line behavior that should be carefully accounted byincluding the superconducting material properties into the modeling. Nb superconductor, as themost commonly exploited material, was used in this study for modeling of the superconductingmicrostrip though the same approach would work for any different BCS superconductingmaterial. The purpose of this paper is to introduce a new model for SML and compare it withpreviously suggested models and results of SML numerical simulation.
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| 5. |
- Nyström, Olle, 1979, et al.
(författare)
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A Vector Beam Measurement System for 211-275 GHz
- 2006
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Ingår i: Proceedings 17th International Symposium on Space Terahertz Technology, Paris, FRANCE.. ; , s. P2-28
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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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| 6. |
- Nyström, Olle, 1979, et al.
(författare)
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A Vector Beam Measurement System for 211-275 GHz
- 2006
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Ingår i: Proceedings EuCAP 2006, Nice, France, 6-10 November 2006, (ESA SP-626, October 2006). - 9290929375
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Konferensbidrag (refereegranskat)abstract
- In this paper, we describe a novel vector measurement system for the characterization of Gaussian beams and present test results for mm-wave, 211-275 GHz, receiver optics alignment. The measurement setup allows a simpler design without any PLLs and employs a combination of a single frequency source, comb-generator, and direct multiplication LO and signal sources. The system takes advantage of different harmonics to generate the required RF and LO signals yielding the desired IF frequency while obtaining perfect phase-coherence and initial phase-noise cancellation. One of the additional advantages of the suggested measuring scheme is that it allows such design that it has the potential to cover different mm and sub-mm bands by only replacing two filters and the LO multiplication unit. For example, we plan to use the same setup, with mentioned modifications, for the frequency bands 275-370 GHz and 385-500 GHz.
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| 7. |
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| 8. |
- Risacher, C., et al.
(författare)
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A 279-381 GHz SIS Receiver for the APEX Telescope
- 2006
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Ingår i: Proceedings of the 16th International Symposium on Space Terahertz Technology, Chalmers University of Technology, Gothenburg, Sweden, May 2-4, 2005. ; , s. 432-437
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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| 9. |
- Vassilev, Vessen, 1969, et al.
(författare)
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A Swedish heterodyne facility instrument for the APEX telescope
- 2008
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 490:3, s. 1157-1163
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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 threebands 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.
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| 10. |
- Vassilev, Vessen, 1969, et al.
(författare)
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MMIC-Based Components for MM-Wave Instrumentation
- 2010
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Ingår i: IEEE Microwave and Wireless Components Letters. - 1558-1764 .- 1531-1309. ; 20:10, s. 578-580
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- In this letter, we present results of fully integrated 90-130 GHz receiver based on 100 nm mHEMT technology. The receiver contains a low noise amplifier (LNA), mixer and LO multiplier chain integrated into a single monolithic microwave integrated circuit (MMIC). The circuit is packaged into a waveguide block, characterized and compared to on-wafer measurements. Waveguide to microstrip transitions are used to interface the MMIC to the waveguide. A breakout LNA circuit is also packaged, and its performance is compared to the receiver. The LNA noise was characterized on a wafer and after packaging. The packaged module is measured at both room and cryogenic temperatures, NF of 3.7 dB is measured at 300 K and 0.9 dB at 20 K.
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