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首页> 外文期刊>Astronomy and astrophysics >The EMIR multi-band mm-wave receiver for the IRAM 30-m telescope
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The EMIR multi-band mm-wave receiver for the IRAM 30-m telescope

机译：用于IRAM 30米望远镜的EMIR多波段毫米波接收机

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Aims. The prime motivation of this project was to design and build a state-of-art mm-wave heterodyne receiver system to enhance the observing throughput of the IRAM 30-m radiotelescope. More specifically, the requirements were i)?state-of-art noise performance for spectroscopic observations; ii)?simultaneous dual polarization and dual-frequency observing; iii)?coverage of the atmospheric transmission windows from 83 to 360?GHz; iv)?compact footprint and minimal maintenance. Methods. Key elements for low noise performance of heterodyne mixers are the superconducting Niobium junctions, operating at ??4?K. These junctions are embedded in carefully designed coupling structures; furthermore, since atmospheric radiation is a significant contributor to the system noise budget, all mixers are either sideband separating or sideband rejecting. To achieve low noise, it is also essential to maximize the coupling of the receiver to the astronomical source, and to minimize the coupling to thermal radiation from the ground-based environment; this is achieved through mirror optics that realize a wavelength-independent coupling to the telescope. A flexible configuration of mirrors and frequency selective surfaces permits various combinations of frequency bands, as well as dual-load radiometric calibration. Low noise intermediate frequency amplifiers and bias electronics also play an important role in the system performance. Results. The EMIR receiver in operation at the 30?m telescope offers four frequency bands: B1: 83?117?GHz, B2: 129?174?GHz, B3: 200?267?GHz, and B4: 260?360?GHz. In each band, the two orthogonal polarizations are observed simultaneously. Dual-band combinations B1/2 B1/3, and B2/4 are available. Bands?1 and?4 (also 3 as of Nov.-2011) feature sideband separation. In dual-band configuration, including sideband separation and polarization diplexing, up to eight IF channels are delivered to the spectrometers, totaling up to 64?GHz of signal bandwidth (of which 32?GHz can be transported and processed by spectrometers, status Nov.-2011). The EMIR receiver has been in continuous operation for more than two years and has allowed, through a qualitative jump in performance, observations not possible before, as shown by a few selected examples of astronomical results.
机译：目的该项目的主要动机是设计和构建最先进的毫米波外差接收器系统，以增强IRAM 30-m无线望远镜的观测吞吐量。更具体地说，要求是：i）光谱观察的最新噪声性能; dual）同时进行双极化和双频观测; iii）覆盖从83到360？GHz的大气传输窗口; iv）紧凑的占地面积和最少的维护。方法。外差混频器低噪声性能的关键要素是超导铌结，工作在?? 4？K。这些结点嵌入精心设计的耦合结构中。此外，由于大气辐射是系统噪声预算的重要贡献，因此所有混频器都是边带分离或边带抑制。为了实现低噪声，还必须使接收器与天文源的耦合最大化，并使与地面环境的热辐射的耦合最小;这是通过镜面光学器件实现的，该镜面光学器件实现了与望远镜的波长独立耦合。反射镜和频率选择表面的灵活配置允许频段的各种组合以及双负载辐射测量校准。低噪声中频放大器和偏置电子器件在系统性能中也起着重要作用。结果。运行在30？m望远镜上的EMIR接收器提供四个频带：B1：83？117？GHz，B2：129？174？GHz，B3：200？267？GHz和B4：260？360？GHz。在每个波段中，同时观察到两个正交极化。提供双频组合B1 / 2 B1 / 3和B2 / 4。频段1和4（截至2011年11月也为3）具有边带分离功能。在双频配置中，包括边带分离和极化双工，最多可将八个IF通道传输到光谱仪，信号带宽总计可达64？GHz（其中11？2可以由光谱仪传输和处理）。 -2011）。 EMIR接收器已经连续运行了两年以上，并且通过性能的大幅提高，允许进行以前不可能的观察，如一些选定的天文结果示例所示。

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