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1.
The specifications of the Atacama large millimeter array (ALMA) have placed stringent requirements on the mechanical performance of its antennas. As part of the evaluation process of the VertexRSI and Alcatel EIE Consortium (AEC) ALMA prototype antennas, measurements of the path length, thermal, and azimuth bearing performance were made under a variety of weather conditions and observing modes. The results of mechanical measurements, reported here, were compared to the antenna specifications. 相似文献
2.
Geoffrey A. Ediss Joshua Crabtree Kirk Crady Erik Gaines Morgan McLeod Greg Morris Rick Williams Antonio Perfetto John Webber 《Journal of Infrared, Millimeter and Terahertz Waves》2010,31(10):1182-1204
The Atacama Large Millimeter/submillimeter (ALMA) Array Front End (FE) system is the first element in a complex chain of signal
receiving, conversion, processing and recording. 70 Front Ends will be required for the project. The Front End is designed
to receive signals in ten different frequency bands. In the initial phase of operations, the antennas will be fully equipped
with six bands. These are Band 3 (84–116 GHz), Band 4 (125–163 GHz), Band 6 (211–275 GHz), Band 7 (275–373 GHz), Band 8 (385–500 GHz)
and Band 9 (602–720 GHz). It is planned to equip the antennas with the missing bands at a later stage of ALMA operations,
with a few Band 5 (163–211 GHz) and Band 10 (787–950 GHz) receivers in use before the end of the construction project. The
ALMA Front End is far superior to any existing receiver systems; spin-offs of the ALMA prototypes are leading to improved
sensitivities in existing millimeter and submillimeter observatories. The Front End units are comprised of numerous elements,
produced at different locations in Europe, North America and East Asia and are integrated at several Front End integration
centers (FEIC) to insure timely delivery of all the units to Chile. The North American FEIC (NA FEIC) is at the National Radio
Astronomy Observatory facility in Charlottesville, Virginia, USA. This paper describes the design and performance of the test
set used at the NA FEIC to check the performance of the Front Ends, following integration and prior to shipment to Chile. 相似文献
3.
A . Gonzalez V. Tapia R. Finger C.-D. Huang S. Asayama Y.-D. Huang 《Journal of Infrared, Millimeter and Terahertz Waves》2017,38(10):1215-1231
The Atacama Large Millimeter/Sub-millimeter Array (ALMA) is currently the largest (sub-)mm wave telescope in the world and will be used for astronomical observations in all atmospheric windows from 35 to 950 GHz when completed. The ALMA band 1 (35–50 GHz) receiver will be used for the longest wavelength observations with ALMA. Because of the longer wavelength, the size of optics and waveguide components will be larger than for other ALMA bands. In addition, all components will be placed inside the ALMA cryostat in each antenna, which will impose severe mechanical constraints on the size and position of receiver optics components. Due to these constraints, the designs of the corrugated feed horn and lens optics are highly optimized to comply with the stringent ALMA optical requirements. In this paper, we perform several tolerance analyses to check the impact of fabrication errors in such an optimized design. Secondly, we analyze the effects of operating this optics inside the ALMA cryostat, in particular the effects of having the cryostat IR filters placed next to the band 1 feed horn aperture, with the consequent near-field effects. Finally, we report on beam measurements performed on the first three ALMA band 1 receivers inside test cryostats, which satisfy ALMA specifications. In these measurements, we can clearly observe the effects of fabrication tolerances and IR filter effects on prototype receiver performance. 相似文献
4.
Stéphane Claude Pat Niranjanan Frank Jiang Dave Duncan Dominic Garcia Mark Halman Haoling Ma Ivan Wevers Keith Yeung 《Journal of Infrared, Millimeter and Terahertz Waves》2014,35(6-7):563-582
This paper presents the performance of production Band 3 receivers (84-116 GHz) for the Atacama Large Millimeter Array (ALMA) that operate in Chile at 5000 m altitude. The fabrication, and testing of a total of 73 receivers necessitated stringent quality control during assembly and custom designed automated test set for accurate and reproducible measurement results. Interfaces to the ALMA receiver system are described in details. The average single side band noise temperature of band 3 production receivers is 33.2 K, with a minimum of 24.4 K and a maximum of 45.5 K. As for image rejection, the average is 18 dB, with a minimum at 12 dB and a maximum of 21 dB. Other performances with test methodology are described such as gain variation within the IF band, the gain and phase stability, gain compression, and beam patterns. This paper also describes the interfaces to the ALMA front end system, the testing methodology used, and the test results. 相似文献
5.
6.
DeBoer D.R. Gough R.G. Bunton J.D. Cornwell T.J. Beresford R.J. Johnston S. Feain I.J. Schinckel A.E. Jackson C.A. Kesteven M.J. Chippendale A. Hampson G.A. O'Sullivan J.D. Hay S.G. Jacka C.E. Sweetnam T.W. Storey M.C. Ball L. Boyle B.J. 《Proceedings of the IEEE. Institute of Electrical and Electronics Engineers》2009,97(8):1507-1521
The Australia SKA Pathfinder (ASKAP) is a new telescope under development as a world-class high-dynamic-range wide-field-of-view survey instrument. It will utilize focal plane phased array feeds on the 36 12-m antennas that will compose the array. The large amounts of data present a huge computing challenge, and ASKAP will store data products in an archive after near real-time pipeline processing. This powerful instrument will be deployed at a new radio-quiet observatory, the Murchison Radio-astronomy Observatory in the midwest region of Western Australia, to enable sensitive surveys of the entire sky to address some of the big questions in contemporary physics. As a pathfinder for the SKA, ASKAP will demonstrate field of view enhancement and computing/processing technology as well as the operation of a large-scale radio array in a remote and radio-quiet region of Australia. 相似文献
7.
Deschans David Begueret Jean-Baptiste Deval Yann Scarabello Christophe Fouillat Pascal Montignac Guy Baudry Alain 《Analog Integrated Circuits and Signal Processing》2006,49(1):31-38
This paper presents the design and the measurement results of a high speed A/D converter (ADC or digitizer) developed for
radio-astronomy applications and especially for the ALMA (Atacama Large Millimeter Array) project. This monolithic digitizer
is implemented in a BiCMOS 0.35 μm SiGe process for high frequency mixed-signal applications. The main characteristics of
this circuit are a 2 bits resolution with 3 quantization levels (equivalent to 1.5 bits) with 4 Gsample/s rate, a wide input
bandwidth from 2 GHz up to 4 GHz under full Nyquist condition. The adopted digitizer architecture is that of a conventional
flash analog to digital converter structure. The overall chip dissipates 652 mW under ± 1.25 V supply and the die area is
5.4 mm2. 相似文献
8.
Mamoru Kamikura Yu Tomimura Yutaro Sekimoto Shin’ichiro Asayama Wenlei Shan Naohisa Satou Yoshizou Iizuka Tetsuya Ito Toshiaki Kamba Yasutaka Serizawa Takashi Noguchi 《Journal of Infrared, Millimeter and Terahertz Waves》2006,27(1):37-53
We have developed a 385–500 GHz sideband-separating (2SB) mixer, which is based on a waveguide split-block coupler at the edge of the H-plane of the 508 μm × 254 μm (WR 2.0) waveguide, for the Atacama Large Millimeter/submillimeter Array (ALMA). An RF/LO coupler, which contains an RF quadrature hybrid, two LO couplers, and an in-phase power divider, was designed with the issue of mechanical tolerance taken into account. The RF/LO coupler was measured optically with a microscope and electrically with a submillimeter vector network analyzer. The image rejection ratio (IRR) and the single-sideband (SSB) noise temperature of the receiver using the RF/LO coupler have also been measured. The IRR was found to be larger than 8 dB and typically ~ 12 dB in the 385–500 GHz band. The SSB noise temperature of this receiver is 80 K at the band center, which corresponds to 4 times the quantum noise limit (hf/k) in SSB, and 250 K at the band edges. 相似文献
9.
《Proceedings of the IEEE. Institute of Electrical and Electronics Engineers》1973,61(9):1278-1282
A fixed-baseline millimeter-wave interferometer, operating initially at 13.5 mm, has been put into operation at the Hat Creek Observatory as the first step in the development of a two-element aperture synthesis telescope. The first system consists of a 3-m antenna and a 6-m antenna spaced 265 m apart. Large receiver bandwidths may be used at high frequencies, and this system employs an intermediate frequency bandwidth of about 400 MHz. It also has automatic gain control and a phase stabilized local-oscillator reference cable. Observations may be made either in the continuum or with a 128-channel spectrometer. The baseline vector has been obtained from observations of about 7 QSO's. The instrument has been used to derive accurate absolute positions of interstellar water vapor sources, to study Mercury, Venus, and Mars, and to make crude maps of a few complex continuum sources. Measurements of the interferometer phase fluctuations due to the atmosphere indicate that interferometer is possible under average weather conditions at Hat Creek at wavelengths as short as 2 mm. The synthesis telescope, the next stage, has two 6-m antennas which can be located at various stations on a T-shaped track. The east-west leg is 300 m and the north-south leg is 200 m, permitting full synthesis for sources on the equator and at declinations as low as -30° as well as at high declinations. Operation at wavelengths down to 2 mm will be possible with resolution of 1"-2". 相似文献
10.
The latest generation of Cassegrain radio astronomy antennas is designed for multiple frequency bands with receivers for individual bands offset from the antenna axis. The offset feed arrangement typically has two focusing elements in the form of ellipsoidal mirrors in the optical path between the feed horn and the antenna focus. This arrangement aligns the beam from the offset feed horn to illuminate the subreflector. The additional focusing elements increase the number of design variables, namely the distances between the horn aperture and the first mirror and that between the two mirrors, and their focal lengths. There are a huge number of possible combinations of these four variables in which the optics system can take on. The design aim is to seek the combination that will give the optimum antenna efficiency, not only at the centre frequency of the particular band but also across its bandwidth. To pick the optimum combination of the variables, it requires working through, by computational mean, a continuum range of variable values at different frequencies which will fit the optics system within the allocated physical space. Physical optics (PO) is a common technique used in optics design. However, due to the repeated iteration of the huge number of computation involved, the use of PO is not feasible. We present a procedure based on using multimode Gaussian optics to pick the optimum design and using PO for final verification of the system performance. The best antenna efficiency is achieved when the beam illuminating the subreflector is truncated with the optimum edge taper. The optimization procedure uses the beam’s edge taper at the subreflector as the iteration target. The band 6 receiver optics design for the Atacama Large Millimetre Array (ALMA) antenna is used to illustrate the optimization procedure. 相似文献
11.
《Microwave and Wireless Components Letters, IEEE》2009,19(6):353-355
12.
The TOPSAR interferometric radar topographic mapping instrument 总被引:8,自引:0,他引:8
Zebker H.A. Madsen S.N. Martin J. Wheeler K.B. Miller T. Lou Y. Alberti G. Vetrella S. Cucci A. 《Geoscience and Remote Sensing, IEEE Transactions on》1992,30(5):933-940
The authors have augmented the NASA DC-8 AIRSAR instrument with a pair of C -band antennas displaced across track to form an interferometer sensitive to topographic variations of the Earth's surface. During the 1991 DC-8 flight campaign, data were acquired over several sites in the US and Europe, and topographic maps were produced from several of these flight lines. Analysis of the results indicate that statistical errors are in the 2-4-m range, while systematic effects due to aircraft motion are in the 10-20-m range. The initial results from development of a second-generation processor show that aircraft motion compensation algorithms reduce the systematic variations to 2 m, while the statistical errors are reduced to 2-3 m 相似文献
13.
针对明安图射电频谱日像仪(Mingantu spectral radioheliograph,MUSER)天线高指向精度动态跟踪要求,同时为降低非理想因素对复杂系统天线指向测量影响,提出校准天线指向的组合方法.先用网格法测量天线的双圆极化多频率通道立体方向图定性评估系统测量链路状态,后对太阳运行轨道进行十字跟踪扫描测量天线指向偏差,再用最小二乘法拟合获得天线指向模型的8个参数.国家天文台明安图观测基地的2台20 m地平式天线将在MUSER系统观测和校准中起重要作用.对20 m天线跟踪指向进行了校准,指向偏差均方根从12'改善到4.4',验证了方法的可行性,为类似复杂系统的相关工作提供了借鉴和参考. 相似文献
14.
Padin S. Cartwright J.K. Joy M. Meitzler J.C. 《Antennas and Propagation, IEEE Transactions on》2000,48(5):836-838
Design and performance details are given for a 0.9-m diameter shielded cassegrain antenna, which will be used in a 13-element close-packed array, The array is designed to make images of brightness fluctuations in the cosmic microwave background radiation. Coupling between a pair of the shielded cassegrain antennas with a separation of 1 m is in the range -110 to -130 dB over the 26- to 36-GHz band 相似文献
15.
16.
Takafumi Kojima Kouichi Kuroiwa Yoshinori Uzawa Matthias Kroug Masanori Takeda Yasunori Fujii Keiko Kaneko Akihira Miyachi Zhen Wang Hideo Ogawa 《Journal of Infrared, Millimeter and Terahertz Waves》2010,31(11):1321-1330
We have developed a low-noise heterodyne waveguide Superconductor-Insulator-Superconductor (SIS) mixer with a novel local
oscillator (LO) injection scheme for the Atacama Large Millimeter/submillimeter Array (ALMA) band 10, over the frequency range
0.78–0.95 THz. The SIS mixer uses radio frequency (RF) and LO receiving horns separately and a waveguide 10 dB LO coupler
integrated in the mixer block. The insertion loss of the waveguide and coupling factor of the coupler were evaluated at terahertz
frequencies at both room and cryogenic temperatures. The double-sideband (DSB) receiver noise temperatures were below 330 K
(7.5hf/k
B) at LO frequencies in the range 0.801–0.945 THz. The minimum temperature was 221 K at 0.873 THz over the intermediate frequency
range of 4–12 GHz at an operating temperature of 4 K. This waveguide heterodyne SIS mixer exhibits great potential for practical
applications, such as high-frequency receivers of the ALMA. 相似文献
17.
18.
WISP/HF is the high-frequency part of the collaborative U.S.- Canada investigation, Waves In Space Plasmas. Instrumentation is being developed that will be flown on NASA's Space Shuttle starting with the Space Plasma Lab missions in the 1990s. Using a high-inclination orbit at heights near the maximum density of the ionospheric F region, active experiments will be carried out on antennas, electromagnetic and electrostatic wave propagation, problems in linear and nonlinear plasma physics, large-scale ionospheric structures, ionospheric irregularities, and the interaction of charged-particle beams with the ionospheric plasma. The WISP/HF equipment will generate, receive, and process signals in the 0.1 - to 30-MHz range. The Orbiter-based transmitter will have variable pulse-power levels up to 0.5 kW and will use a dipole of variable length up to 300 m tip-to-tip. WISP/HF receivers will be located both on the Orbiter and on a subsatellite. A high level of operational flexibility in the WISP/HF instrument design has been achieved through programmable digital control. The design also permits human control of experiments, both from the Orbiter and from the ground. 相似文献
19.
Pablo Zorzi Christophe Granet Franco Colleoni Nicolas Reyes Jose Pizarro Fausto-Patricio Mena Leonardo Bronfman 《Journal of Infrared, Millimeter and Terahertz Waves》2012,33(1):17-24
A corrugated spline-profile horn has been designed to meet the stringent specifications and constraints of a receiver for
Band 1 (31.3–45 GHz) of the Atacama Large Millimeter Array (ALMA). Given the physical restrictions of the receiver, the horn
will be located behind a focusing lens placed 191 mm over its aperture. After this first focusing stage, the horn must have
a reflection coefficient less than −20 dB and the cross-polarization not exceeding the −30 dB level in the entire frequency
range. The side-lobes should be less than −25 dB at all frequencies and its half power beamwidth must be approximately 24°
at 31.3 GHz and 16° at 45 GHz. The horn has been constructed using the split-block technique and characterized in a near-field
scanner setup. The results show an excellent performance complying with all the requirements. 相似文献
20.
Dickinson R.M. Losh D.L. Barber R.D. Dempsey J.K. 《Antennas and Propagation, IEEE Transactions on》1999,47(3):487-495
Signal combining efficiencies of 98% have been achieved on low-Earth orbiting (LEO) debris with phase-locking of time-overlapped radar pulses from a two-element phased-array consisting of two 34-m beam waveguide steerable paraboloid antennas separated by 204 m. The uplink arraying at 7.19 GHz has been achieved for tracks from about 10° elevation at signal rise to 4° elevation at signal set under varying weather conditions (e.g., hail failing on one antenna). The typical root mean square (RMS) phase error for two coherent 100-μs 50-Hz 5-kW peak pulses reflected from LEO debris with signal-to-noise ratio (SNR) >23 dB is less than 4°. The phase-control system design, methods of calibration, and details of the design control table of phasing error contributors are presented and discussed. Based upon the measured performance, we predict that transmitting antennas for the Deep Space Network (DSN) could be coherently arrayed for up to hours at a time given static phase error calibrations on exo-atmospheric debris. Applications for this technique include low-cost implementation of high-power microwave transmitters for deep-space communication and radars for exploration of other planets and as part of a defense against comets and asteroids 相似文献