| 1. |
- Alef, Walter, et al.
(författare)
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BRAND - The next generation receiver for VLBI
- 2018
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Ingår i: Proceedings of Science. - Trieste, Italy : Sissa Medialab. - 1824-8039. ; 344
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Konferensbidrag (refereegranskat)abstract
- The aim of the BRAND EVN project is to build a very wide receiver prototype for primary focus with a frequency range from 1.5 GHz to 15.5 GHz In addition we will investigate solutions for secondary focus telescopes. The project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 730562 [RadioNet]. We present the status of the project which was started on January 1st, 2017 and is progressing smoothly: Feed, LNA, filters, major digital components, and some of the firmware are available now. © Copyright owned by the author(s) under the terms of the Creative Commons.
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| 2. |
- Belitsky, Victor, 1955, et al.
(författare)
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A new 3 mm band receiver for the Onsala 20 m antenna
- 2015
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 580
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Tidskriftsartikel (refereegranskat)abstract
- A new receiver for the Onsala 20 m antenna with the possibility of being equipped with 3 mm and 4 mm bands has been built and the 3 mm channel has been commissioned during the Spring 2014. For single-dish operation, the receiver uses an innovative on-source/off-source optical switch. In combination with additional optical components and within the same optical layout, the switch provides two calibration loads (for the 3 mm and 4 mm channels), sideband rejection measurement, and tuning possibilities. The optical layout of the receiver employs all cold (4 K) offset elliptical mirrors for both channels, whereas the on-off switch employs flat mirrors only. The 3 mm channel employs a sideband separation (2SB) dual polarization receiver with orthomode transducer (OMT), 4-8 GHz intermediate frequency (IF), x? 2pol x? upper and lower sidebands (USB? +? LSB). The cryostat has four optical windows made of high density polyethylene (HDPE) with anti-reflection corrugations, two for the signal and two for each frequency band cold load. The cryostat uses a two-stage cryocooler produced by Sumitomo HI? RDK? 408D2 with anti-vibration suspension of the cold-head to minimize impact of the vibrations on the receiver stability. The local oscillator (LO) system is based on a Gunn oscillator with aphase lock loop (PLL) and four mechanical tuners for broadband operation, providing independently tunable LO power for each polarization. This paper provides a technical description of the receiver and its technology and could be useful for instrumentation engineers and observers using the Onsala 20 m telescope.
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| 3. |
- Billade, Bhushan, 1982, et al.
(författare)
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A Wide-band Feed System for SKA Band 1 Covering Frequencies From 350 - 1050 MHz
- 2016
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Ingår i: 10th European Conference on Antennas and Propagation, EuCAP 2016; Davos; Switzerland; 10 April 2016 through 15 April 2016. - 2164-3342. - 9788890701863 ; , s. Art. no. 7481794-
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Konferensbidrag (refereegranskat)abstract
- We present the design of a wideband feed system for the Band 1 of the Square Kilometer Array (project). The Band 1 feed system uses a quad-ridged flared horn (QRFH) optimizedfor a offset Gregorian dual reflector dish to cover RF frequencies from 350 - 1050 MHz, and a cryogenic low noise amplifier (LNA). The feed horn is optimized to achieve best Aeff/Tsys over the entire band, by making trade-off between aperture efficiency and spill over noise contribution. The optimised feed horn shows above 70% efficiency over the entire 3:1 band, with return loss better than 10 dB. The cryostat following the feed has between 9 to 14 K noise, measured at the co-axial connector of the QRFH. The estimated on-sky sensitivity of the feed system is better than specified 4.2 m2/K averaged over the entire frequency band.
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| 4. |
- Dong, Bin, 1984, et al.
(författare)
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Design of an Asymmetrical Quadruple-ridge Flared Horn Feed: a Solution to Eliminate Polarization Discrepancy in the Offset Reflecting Systems
- 2018
-
Ingår i: IET Conference Publications. ; 2018:CP741
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Konferensbidrag (refereegranskat)abstract
- Quadruple-ridge Flared Horns (QRFHs) have been showing qualified performance as the feed antennas for the reflecting systems in the Square Kilometre Array (SKA). However, due to the offset optics of the SKA reflecting system, identical illuminations from dual polarizations of the feed would but result in different system performance. This difference would become more severe towards high frequencies and may cause the worse polarization unqualified for the desired specification. In this paper, an asymmetrical QRFH feed working over Band B (4.6–24 GHz) is proposed and optimized to tackle this problem.The asymmetrical Band-B feed is composed of two different and orthogonal pairs of both ridges and sidewall quad-pieces, so as to provide orthogonal polarizations but different illuminations. Simulated results show that, by this asymmetrical design different beamwidths and different combinations of sub-efficiencies can be provided for two polarizations, so as to eliminate the polarization discrepancy over most of the bandwidth. Benefitting from this elimination, both polarizations of the Band-B feed have now achieved the SKA specification in terms of aperture efficiency.
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| 5. |
- Dong, Bin, 1984, et al.
(författare)
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Optimization and Realization of Quadruple-ridge Flared Horn with New Spline-defined Profiles as a High-efficiency Feed over 4.6–24 GHz
- 2019
-
Ingår i: IEEE Transactions on Antennas and Propagation. - 0018-926X .- 1558-2221. ; 67:1, s. 585-590
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, we present a new optimization and realization of a quadruple-ridge flared horn (QRFH) as a feed for reflector antennas of the Square Kilometre Array (SKA) project. The QRFH has been numerically optimized by spline-defined profiles for both the ridges and the horn sidewall, with a conical cavity in the back-short for maximum aperture efficiency. The final aperture efficiency better than (for horizontal polarization) or around (for vertical polarization) 78% over 4.6–8 GHz, 70% over 8–15 GHz, 65% over 15–20 GHz and 60% over 20–24 GHz in the SKA offset-Gregorian dual-reflector antenna has been achieved. The realization of the horn has been carried out carefully by applying several new mechanical design solutions in order to guarantee the accurate positioning of the ridges, the feeding pins and a good electrical contact. The measured S11 is mostly better than -10 dB and the predicted aperture efficiency based on the measured far field patterns agrees well with the simulated result. System performance, such as the sensitivity and system noise temperature, are also estimated and presented.
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| 6. |
- Elgered, Gunnar, 1955, et al.
(författare)
-
The Onsala Twin Telescopes Project
- 2017
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Ingår i: The 23rd Working Meeting of the European VLBI Group for Geodesy and Astrometry (EVGA), Gothenburg, May 14–18, 2017.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The Onsala Space Observatory is the European site in the International VLBI Service for Geodesy and Astrometry (IVS) that has the longest history in VLBI. First geodetic VLBI measurements were performed already in 1968 with the 25 m radio telescope. Onsala is today one of the sites with thelongest time series in the IVS data base. The observatory is one of the unique fundamental space geodetic sites that have a direct access to the coast line and co-locate VLBI, GNSS, gravimetry, and sea-level monitoring. Onsala is thus an important co-location site for the GlobalGeodetic Observing System (GGOS). Being well aware of the VGOS standard it was clear around 2010 that Onsala was in need for a telescope with significantly faster slew rates than the existing radome-enclosed 20 m telescope.
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| 7. |
- Elgered, Gunnar, 1955, et al.
(författare)
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The Onsala Twin Telescopes: the Status at the Time for the Inauguration
- 2017
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Ingår i: Proceedings of the 23rd European VLBI Group for Geodesy and Astrometry Working Meeting. - 9789188041098 ; , s. 136-139
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- We summarise the activities related to the Onsala Twin Telescopes (OTT), from the time when the decision was taken to fund the proposal, to the inauguration on 18 May 2017.
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| 8. |
- Fan, Jin, et al.
(författare)
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Design of Octave-bandwidth Phased Array Feed for Large Radio Telescope
- 2019
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Ingår i: 13th European Conference on Antennas and Propagation, EuCAP 2019.
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Konferensbidrag (refereegranskat)abstract
- This paper presents design scenarios of Octave-bandwidth Phase Array Feed (PAF) based on a novel wideband dual polarized tightly-fed Bowtie antenna element. The PAF is optimized for the 4 - 8GHz band aiming to possible later integration in the SKA pathfinder PHAROS2. The proposed design can be a good candidate of PAF for the Five hundred meter Aperture Spherical Telescope (FAST) and Qi Tai Telescope (QTT) as well as other large radio telescopes.
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| 9. |
- Flygare, Jonas, 1988, et al.
(författare)
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Beam pattern measurement on offset Gregorian reflector mounted with a wideband room temperature receiver for the Square Kilometre Array
- 2018
-
Ingår i: 2018 IEEE International Symposium on Antennas and Propagation & USNC/URSI National Radio Science Meeting (APSURSI2018). - 9781538671023 ; APSURSI 2018, s. 1759-1760
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Konferensbidrag (refereegranskat)abstract
- We present measured on-dish beam patterns for a room temperature spline-profile quad-ridge flared horn (QRFH) feed designed for the Square Kilometre Array (SKA) Band 1 covering 350-1050 MHz. The feed and LNA package has been mounted on the offset Gregorian SKA precursor prototype telescope, Dish Verification Antenna 1 (DVA-1) located at the Dominion Radio Astrophysical Observatory (DRAO) near Penticton, British Columbia, Canada. Telescope beam pattern cuts are measured by sweeping over the sun and adding corrections for the solar disk size, elevation and aperture efficiency. Sensitivity calculated with measured receiver noise show good agreement with the predicted performance.
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| 10. |
- Flygare, Jonas, 1988, et al.
(författare)
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BRAND: Ultra-Wideband Feed Development for the European VLBI Network - A Dielectrically Loaded Decade Bandwidth Quad-Ridge Flared Horn
- 2018
-
Ingår i: IET Conference Publications. - : Institution of Engineering and Technology. ; 2018:CP741
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Konferensbidrag (refereegranskat)abstract
- We present the design of an ultra-wideband dielectrically loaded Quad-Ridge Flared Horn (QRFH) feed for the European Very Long Baseline Interferometry Network (EVN) developed under the RadioNet project BRoad-bAND (BRAND). The feed covers a frequency bandwidth ratio of 10:1 and has an average aperture efficiency of 50 percent simulated in primary focus setup on the Effelsberg telescope (f/D = 0.3). The feed is dual-polarized and has an input reflection better than −10 dB over the whole 1.5–15.5 GHz frequency band. We also introduce an Analytic-Spline-Hybrid (ASH) optimization scheme for the QRFH ridge and sidewall profiles.
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| 11. |
- Flygare, Jonas, 1988, et al.
(författare)
-
Design trade-offs in feed systems for ultra-wideband VLBI observations
- 2018
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Due to the advanced capability of today’s ultra-wideband feed systems and low-noise amplifiers, interesting upgrades for future VLBI receiver and tele- scope design should be considered. Multiple input pa- rameters need to be taken into account for optimal sensitivity and applications of the future astronomical and geodetic observational systems. In this paper we present an overview of some trade-offs for wideband systems between SEFD, bandwidth and telescope re- flector optics. We evaluate receiver bandwidths from 3.5:1 to 10.3:1 bandwidth within the frequency range 1.5-24 GHz in different configurations. Due to poten- tial RFI-pollution of the lower frequencies we present potential feed upgrades for the most common reflector geometries ofVGOS and EVN telescopes that mitigate this problem. The results of this work is relevant for fu- ture VLBI stations and telescope design in general. Keywords
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| 12. |
- Flygare, Jonas, 1988, et al.
(författare)
-
Integrated calibration noise coupler for room temperature SKA band 1 feed system
- 2017
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Ingår i: Proceedings of 2017 IEEE International Symposium on Antennas and Propagation & USNC/URSI National Radio Science Meeting, APSURSI 2017, San Diego, CA, USA, 9-14 July 2017. - 1947-1491. ; 2017, s. 777-778
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Konferensbidrag (refereegranskat)abstract
- This paper presents design of a novel coupler for the injection of calibration signal into the RF path of the SKA Band 1 quad-ridged flared horn, covering frequencies from 350–1050 MHz. The coupler is integrated in the feed horn and provides a coupling factor of −35 dB. The calibration signal is injected before the first amplification stage, without any degradation in the noise performance of the room temperature system.
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| 13. |
- Flygare, Jonas, 1988, et al.
(författare)
-
Sensitivity and Antenna Noise Temperature Analysis of the Feed System for the Onsala Twin Telescopes
- 2017
-
Ingår i: Proceedings of the 23rd European Very Long Baseline Interferometry Group for Geodesy and Astrometry Working Meeting, EVGA2017, Gothenburg, Sweden, 15-19 May 2017. - 9789188041104 ; , s. 10-14
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The demand for higher precision measurements in Very Long Baseline Interferometry (VLBI) continues to grow, which drives the technical development of next generation international VLBI stations called the VLBI Global Observing System (VGOS). The VGOS design includes the idea of twin telescopes, i.e. two identical telescopes that will be used for continuous observations to study geodynamical processes. Such a twin telescope system has recently been installed at the Onsala Space Observatory, Sweden. The Onsala twin telescopes (OTT) are 13.2 m diameter, dual-reflector systems with a ring-focus sub-reflector. In this paper we present the estimated performance, focusing on the achievable system equivalent flux density (SEFD), sky noise modeling, and antenna noise temperature. We evaluate the system for two different cryogenic wideband quad-ridge flared horn (QRFH) feed setups operating over 3-18 GHz and 4.6-24 GHz. Analysis based on measured feed data shows a low antenna noise temperature and that SEFD of 1000 Jy can be achieved for the system. The result from Y-factor test shows TREC = 10 K over most of the frequency band.
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| 14. |
- Flygare, Jonas, 1988, et al.
(författare)
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Sensitivity simulation and measurement of the SKA Band 1 wideband feed package on MeerKAT
- 2019
-
Ingår i: 13th European Conference on Antennas and Propagation, EuCAP 2019. ; EuCAP 2019
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Konferensbidrag (refereegranskat)abstract
- Advances in wideband feed technology for radio telescopes enable high sensitivity observations over large bandwidths. The wideband quad-ridge flared horn (QRFH) feed package for Band 1 of the Square Kilometre Array (SKA) was optimized for high sensitivity. The 3:1 feed package covers 350-1050 MHz and is a complete room temperature system with low-noise amplifiers integrated inside the ridges of the horn. The QRFH is dual-linear polarized and designed with spline-defined profiles for the horn and ridge shape. Measured feed s-parameters show input reflection less than -11 dB across the band with good port isolation. In this paper we present the first measured sensitivity levels of the Band 1 feed package, which was tested on the SKA precursor reflector MeerKAT. We also present measured aperture efficiency and intrinsic cross-polarization (IXR). The measured results show good agreement with simulations.
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| 15. |
- Flygare, Jonas, 1988, et al.
(författare)
-
Ultra-wideband feed systems for the EVN and SKA - evaluated for VGOS
- 2018
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The design of the Square Kilometre Array (SKA) project for radio astronomy is now materializing at a rapid speed; the EU Horizon 2020 RadioNet project BRoad-bAND (BRAND) has the ambition to deliver a decade bandwidth receiver for EVN. The ultra-wideband quad-ridge flared horn (QRFH) feed systems developed for these projects show good performance within the geodetic VLBI Global Observing System (VGOS) frame due to the overlapping frequency bands and reflector geometries. We estimate, through simulation, system equivalent flux density (SEFD) of the two feed systems in the VGOS reflector and compare the it to the existing system installed on one of the 13.2 m diameter reflectors of the Onsala twin telescope (OTT). The two frequency bands analyzed cover 1.5−15.5 GHz and 4.6−24 GHz. Both systems show SEFD better than 1000 Jy over large parts of resp. frequency band - comparable to the 3−18 GHz feed systems. For the SKA QRFH over 4.6−24 GHz, the water vapor absorption line at 22 GHz is within the operational band, therefore we study the application of water-vapor radiometry in line-of-sight of the telescope.
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| 16. |
- Flygare, Jonas, 1988, et al.
(författare)
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Wideband single pixel feed system over 4.6-24 GHz for the Square Kilometre Array
- 2019
-
Ingår i: Proceedings of the 2019 21st International Conference on Electromagnetics in Advanced Applications, ICEAA 2019. ; , s. 630-635
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Konferensbidrag (refereegranskat)abstract
- We present the Band B feed system over 4.6-24 GHz designed for the Square Kilometre Array (SKA) reflector for radio astronomy applications. The feed is a Quad-ridge Flared Horn (QRFH) with a customized shape based on spline-defined profiles to achieve improved wideband performance. The feed system shows high aperture efficiency and sensitivity on the SKA reflector in predictions based on measured feed beam patterns. We present the feed design overview, cryogenic dewar concept and measurement of receiver noise (10-20 K) with wideband low-noise amplifiers, and full system simulation of the performance.
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| 17. |
- Haas, Rüdiger, 1966, et al.
(författare)
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Status of the Onsala Twin Telescopes – One Year After the Inauguration
- 2019
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Ingår i: IVS 2018 General Meeting Proceedings "Global Geodesy and the Role of VGOS – Fundamental to Sustainable Development". ; NASA/CP-2019-219039, s. 17-19
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Konferensbidrag (refereegranskat)abstract
- We briefly describe the status of the Onsala twin telescopes and the experience gained since the official inauguration in May 2017.
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| 18. |
- Navarrini, A., et al.
(författare)
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Design of PHAROS2 Phased Array Feed
- 2018
-
Ingår i: 2018 2nd URSI Atlantic Radio Science Meeting, AT-RASC 2018.
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Konferensbidrag (refereegranskat)abstract
- We describe the design and architecture of PHAROS2, a cryogenically cooled 4-8 GHz Phased Array Feed (PAF) demonstrator with digital beamformer for radio astronomy application. The instrument will be capable of synthesizing four independent single-polarization beams by combining 24 active elements of an array of Vivaldi antennas. PHAROS2, the upgrade of PHAROS (PHased Arrays for Reflector Observing Systems), features: a) commercial cryogenic LNAs with state-of-the-art performance, b) a 'Warm Section' for signal filtering, conditioning and single downconversion to select a≈275 MHz: Intermediate Frequency (IF) bandwidth within the 4-8 GHz Radio Frequency (RF) band, c) an IF signal transportation by analog WDM (Wavelength Division Mutiplexing) fiber-optic link, and d) a FPGA-based Italian Tile Processing Module (iTPM) digital backend. PHAROS2 will be mounted at the primary focus of the 76-m diameter Lovell radio telescope (Jodrell Bank Observatory, UK) for technical and scientific validation.
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| 19. |
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| 20. |
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| 21. |
- Tan, G. H., et al.
(författare)
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An innovative, highly sensitive receiver system for the Square Kilometre Array Mid radio telescope
- 2018
-
Ingår i: Proceedings of SPIE - The International Society for Optical Engineering. - : SPIE. - 0277-786X .- 1996-756X. ; 9906
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Konferensbidrag (refereegranskat)abstract
- The Square Kilometre Array (SKA) Project is a global science and engineering project realizing the next-generation radio telescopes operating in the metre and centimetre wavelengths regions. This paper addresses design concepts of the broadband, exceptionally sensitive receivers and reflector antennas deployed in the SKA1-Mid radio telescope to be located in South Africa. SKA1-Mid (350 MHz -13.8 GHz with an option for an upper limit of similar to 24 GHz) will consist of 133 reflector antennas using an unblocked aperture, offset Gregorian configuration with an effective diameter of 15 m. Details on the unblocked aperture Gregorian antennas, low noise front ends and advanced direct digitization receivers, are provided from a system design perspective. The unblocked aperture results in increased aperture efficiency and lower side-lobe levels compared to a traditional on-axis configuration. The low side-lobe level reduces the noise contribution due to ground pick-up but also makes the antenna less susceptible to ground-based RFI sources. The addition of extra shielding on the sub-reflector provides a further reduction of ground pick-up. The optical design of the SKA1-Mid reflector antenna has been tweaked using advanced EM simulation tools in combination with sophisticated models for sky, atmospheric and ground noise contributions. This optimal antenna design in combination with very low noise, partially cryogenic, receivers and wide instantaneous bandwidth provide excellent receiving sensitivity in combination with instrumental flexibility to accommodate a wide range of astronomical observation modes.
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| 22. |
- Tuccari, Gino, et al.
(författare)
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BRAND: A Very Wide-band Receiver for the EVN
- 2017
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Ingår i: Proceedings of the 23rd European Very Long Baseline Interferometry Group for Geodesy and Astrometry Working Meeting, EVGA2017, Gothenburg, Sweden, 15-19 May 2017. - 9789188041104 ; , s. 81-83
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- BRAND stands for BRoad bAND EVN, a project to build a prototype primary focus receiver with the very wide frequency range from 1.5 GHz to 15.5 GHz, to investigate secondary focus solutions, and to make a survey of the EVN telescopes in order to set the stage for equipping all EVN stations with such a receiver as soon as possible. The project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 730562 and is a Joint Research Activity (JRA) in the RadioNet programme. We present the motivation, aims, scope and status of the project which was started on January 1st, 2017.
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| 23. |
- Wagner, J., et al.
(författare)
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First 230? : GHz VLBI fringes on 3C 279 using the APEX Telescope (Research Note)
- 2015
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 581
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Tidskriftsartikel (refereegranskat)abstract
- Aims. We report about a 230? GHz very long baseline interferometry (VLBI) fringe finder observation of blazar 3C 279 with the APEX telescope in Chile, the phased submillimeter array (SMA), and the SMT of the Arizona Radio Observatory (ARO). Methods. We installed VLBI equipment and measured the APEX station position to 1? cm accuracy (1σ). We then observed 3C 279 on 2012 May 7 in a 5? h 230? GHz VLBI track with baseline lengths of 2800? Mλ to 7200? Mλ and a finest fringe spacing of 28.6? μas. Results. Fringes were detected on all baselines with signal-to-noise ratios of 12 to 55 in 420? s. The correlated flux density on the longest baseline was ∼0.3? Jy beam-1, out of a total flux density of 19.8? Jy. Visibility data suggest an emission region ≤ 38? μas in size, and at least two components, possibly polarized. We find a lower limit of the brightness temperature of the inner jet region of about 1010? K. Lastly, we find an upper limit of 20% on the linear polarization fraction at a fringe spacing of ∼ 38? μas. Conclusions. With APEX the angular resolution of 230? GHz VLBI improves to 28.6? μas. This allows one to resolve the last-photon ring around the Galactic Center black hole event horizon, expected to be 40? μas in diameter, and probe radio jet launching at unprecedented resolution, down to a few gravitational radii in galaxies like M 87. To probe the structure in the inner parsecs of 3C 279 in detail, follow-up observations with APEX and five other mm-VLBI stations have been conducted (March 2013) and are being analyzed.
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| 24. |
- Walker, G. W., et al.
(författare)
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Optical design and verification of the 4mm receiver for the 20m telescope at Onsala Space Observatory
- 2018
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Ingår i: Proceedings of SPIE - The International Society for Optical Engineering. - : SPIE. - 0277-786X .- 1996-756X. ; 10015
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Konferensbidrag (refereegranskat)abstract
- The work of this research is the design, analysis and verification of the optical performance of a 4 mm receiver channel for the 20 m telescope at Onsala Space Observatory, Onsala, Sweden. The 4 mm (75 GHz) receiver is a newly proposed channel designed to be installed parallel to the existing 3 mm (100 GHz) channel targeting new science at that longer wavelength. Gaussian beam mode analysis is used to produce the fundamental optical design of the system. The design is then analysed more accurately with the physical optics approximation. We report on the comparison of simulation and measurement and verification of the system design.
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| 25. |
- Yang, Jian, 1960, et al.
(författare)
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A Compact Dual-Polarized 4-Port Eleven Feed with High Sensitivity for Reflectors over 0.35-1.05 GHz
- 2015
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Ingår i: IEEE Transactions on Antennas and Propagation. - 0018-926X .- 1558-2221. ; 63:12, s. 5955-5960
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Tidskriftsartikel (refereegranskat)abstract
- We present significant improvements to the circular Eleven feed technology for a dual-reflector system operating over 0.35-1.05 GHz as a backup for the square kilometer array (SKA) project Band 1. In this work, the number of the feed ports is reduced to 4 from the previous 8 for dual polarization using a novel geometry at the center. The design is carried out by optimizing with a social civilization algorithm. The resulting improvements include a reflection coefficient below -12dB, an aperture efficiency above 70% at the upper end of the band, a maximum cross-polar level under -15dB, and an ohmic loss about 0.05 dB. A prototype based on this design has been manufactured and the design simulations have been verified against measurements. A simulated sensitivity of the dual-reflector receiver system for the SKA project based on the measured data is also presented in this communication.
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| 26. |
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| 27. |
- Yang, Jian, 1960, et al.
(författare)
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Truly Conical Eleven Antenna: a New Geometry for Applications at High Frequencies
- 2016
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Ingår i: 2016 IEEE Antennas and Propagation Society International Symposium, APSURSI 2016 - Proceedings. - 9781509028863 ; , s. 1583-1584
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Konferensbidrag (refereegranskat)abstract
- A new truly conical geometry of Eleven antenna for high frequency applications is proposed in the paper. By using this geometry, the antenna petal arrays are made on only one piece of flat thin PCB, which is soft enough to be conically bent and strong enough after the conical bending to be fastened stably by only the center pack cone and the outer walls. Therefore, many manufacture difficulties by using previous Eleven antenna geometries have been avoided. Simulated performance of a 4.6–20GHz Eleven feed, -10 dB reflection coefficient and above 60% aperture efficiency when feeding a reflector antenna, is presented as an example in the paper.
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