Design and Characterization of a 211–275 GHz Sideband Separating Mixer for the APEX Telescope

Vassilev, Vessen; Henke, Doug; Lapkin, Igor; Nyström, Olle; Monje, Raquel; Pavolotsky, Alexey; Belitsky, Victor

doi:10.1109/lmwc.2007.912026

Cited by 18 publications

(18 citation statements)

References 5 publications

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“…As a frontend we used the APEX-1 receiver of the SHeFI (Vassilev et al 2008b). The backend was the Fast Fourier Transfrom Spectrometer (FFTS; Klein et al 2006) with a 1 GHz bandwidth divided into 8 192 channels.…”

Section: O(2-1) Line Observationsmentioning

confidence: 99%

LABOCA 870 μm dust continuum mapping of selected infrared-dark cloud regions in the Galactic plane

Miettinen¹

2012

A&A

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Context. Imaging surveys of dust emission at (sub)millimetre wavelengths provide a powerful tool for studying molecular clouds and the early stages of star formation. Aims. Through submm dust continuum mapping, we attempt to search for genuine infrared-dark clouds (IRDCs) and precursors to massive stars and stellar clusters in the Galactic plane, and to determine their basic physical properties. Methods. We have mapped four selected fields of about 0.• 5 × 0.• 5 that contain Spitzer 8-μm dark regions with LABOCA at 870 μm. Selected positions in the fields were observed in C 17 O(2−1) to obtain kinematic information. The obtained LABOCA maps are used in conjunction with the Spitzer IR images. Results. The total number of clumps identified in this survey is 91, out of which 40 (44%) appear dark at 8 and 24 μm. The remaining clumps are associated with mid-IR emission. Seven clumps associated with extended 4.5 μm emission are candidate extended green objects (EGOs). Filamentary dust "ridges" were found towards the Spitzer bubbles N10/11 in one of our fields. The relative number of IR-dark and IR-bright clumps suggests that the duration of the former stage is about 1.6 × 10 5 yr. The mass distribution of the total sample of clumps, and that separately constructed for the IR-dark and IR-bright clumps, could be fitted at the high-mass end with the power-law function dN/dlog M ∝ M −Γ , where Γ 0.7 . . . 0.8. The C 17 O observation positions appear to be dominated by non-thermal motions, and the data also revealed some potential sites of strong CO depletion. In G11.36+0.80, which is the best example of a filamentary IRDC in our sample, the clumps appear to be gravitationally bound. The fragmentation of the filament can be understood in terms of a sausage-type fluid instability, in agreement with the results for other IRDCs. The fragmentation and the CO depletion timescales in G11.36 appear to be very similar to each other. Conclusions. Many of the identified clumps are massive enough to allow high-mass star formation, and some of them already show clear signposts of that. In the N10/11 bubble environment, the morphology of the detected dust emission conforms to the triggered high-mass star formation in the system. The clump mass distributions are similar to those found for diffuse CO clumps, and can be explained by the action of supersonic turbulence. The formation of filamentary IRDCs might be caused by converging turbulent flows, and the same process may play a role in exciting the fluid perturbations responsible for the fragmentation of the clouds into clumps.

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Section: O(2-1) Line Observationsmentioning

confidence: 99%

LABOCA 870 μm dust continuum mapping of selected infrared-dark cloud regions in the Galactic plane

Miettinen¹

2012

A&A

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“…The LO power is applied to the middle of the mixer chip, where a double-probe structure (Vassilev et al 2001) divides the LO power and provides the transition from waveguide to microstrip line. To couple LO power to the junctions, we developed an on-chip directional coupler and a broadband termination based on thin-film microstrip lines (Vassilev et al 2008;Monje et al 2004). The mixer circuitry is based on SIS twin-junctions, where the two junctions are located at the ends of a transmission line so that their reactance is mutually compensated at RF.…”

Section: Bandmentioning

confidence: 99%

A Swedish heterodyne facility instrument for the APEX telescope

Vassilev¹,

Meledin²,

Lapkin³

et al. 2008

A&A

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152

139

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Aims. 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. Methods. 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. Results. 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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“…There are numerous examples of branch guide coupler designs; see [2]- [4], [9]. Many of the 3 dB couplers use relatively narrow branches in standard height rectangular waveguide configuration.…”

Section: A Design Considerations and Approachmentioning

confidence: 99%

“…Its development originates from early work on military radar systems during World War II, which operated at frequencies up to about 300 MHz (see [1] for a historical review of microwave couplers). More recently, it has also been used at submillimeter wave frequencies as an LO/RF hybrid in various sideband separating receivers employing fundamental SIS mixers [2]- [4].…”

Section: Introductionmentioning

confidence: 99%

A 170 GHz 45$^{\circ}$ Hybrid for Submillimeter Wave Sideband Separating Subharmonic Mixers

Sobis

Stake

Emrich

2008

IEEE Microw. Wireless Compon. Lett.

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We present a 135 /45 phase shifter hybrid intended to be used in subharmonic sideband separation mixer schemes at submillimeter-wave frequencies. The design consists of an increased height 90 6-arm branch guide coupler with a three stub loaded differential line 45 phase shifter at the output. The device has been implemented at G-band in an E-plane WR-05 splitblock design with a center frequency of 170 GHz and 15% bandwidth. Measured S-parameter are in good agreement with simulations showing an isolation and return loss better than 20 dB and an amplitude and phase imbalance within 0.4 dB and 2 , respectively.Index Terms-Millimeter wave directional couplers, millimeter wave phase shifters, power dividers, rectangular waveguide filters, terahertz waveguide couplers.

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Design and Characterization of a 211–275 GHz Sideband Separating Mixer for the APEX Telescope

Cited by 18 publications

References 5 publications

LABOCA 870 μm dust continuum mapping of selected infrared-dark cloud regions in the Galactic plane

LABOCA 870 μm dust continuum mapping of selected infrared-dark cloud regions in the Galactic plane

A Swedish heterodyne facility instrument for the APEX telescope

A 170 GHz 45$^{\circ}$ Hybrid for Submillimeter Wave Sideband Separating Subharmonic Mixers

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