A Q-band two-beam cryogenic receiver for the Tianma Radio Telescope

Zhong, Wang; Dong, Junping; Gou, Weiping; Yu, Linfeng; Wang, Jinqing; Xia, Bo; Jiang, Wu; Liu, Cong; Zhang, Hui; Shi, Jun; Yin, Xiaoxing; Shi, Sheng‐Cai; Liu, Qinghui; Shen, Zhi-Qiang

doi:10.1088/1674-4527/18/4/44

Cited by 11 publications

(9 citation statements)

References 30 publications

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“…The Q-band receiver is a two-beam dual-polarization (LCP and RCP) cryogenic receiver, covering a frequency range of 35-50 GHz (Zhong et al 2018). The two beams cannot work simultaneously at present for spectral line observation limited by the backend.…”

Section: Tmrtmentioning

confidence: 99%

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A Q-band Line Survey toward Orion KL Using the Tianma Radio Telescope

Liu

Shen

Qin

et al. 2022

ApJS

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We have conducted a line survey toward Orion KL using the Q-band receiver of the Tianma 65 m radio telescope (TMRT), covering 34.8–50 GHz with a velocity resolution between 0.79 and 0.55 km s−1, respectively. The observations reach a sensitivity of the level of 1–8 mK, proving that the TMRT is sensitive for conducting deep-line surveys. In total, 597 Gaussian features are extracted. Among them, 177 radio recombination lines (RRLs) are identified, including 126, 40, and 11 RRLs of hydrogen, helium, and carbon, with a maximum Δn of 16, 7, and 3, respectively. The carbon RRLs are confirmed to originate from photodissociation regions with a V LSR ∼ 9 km s−1. In addition, 371 molecular transitions of 53 molecular species are identified. Twenty-one molecular species of this survey were not firmly detected in the Q band by Rizzo et al., including species such as H2CS, HCOOH, C2H5OH, H 2 13 CO, H2CCO, CH3CHO, CH2OCH2, HCN υ 2 = 1, and CH3OCHO υ t = 1. In particular, the vibrationally excited states of ethyl cyanide (C2H5CN υ13/υ21) are for the first time firmly detected in the Q band. NH3 (15,15) and (16,16) are identified, and they are so far the highest transitions of the NH3 inversion lines detected toward Orion KL. All of the identified lines can be reproduced by a radiative transfer model.

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Section: Tmrtmentioning

confidence: 99%

“…Only beam 2 was employed during our observations. The receiver noise temperatures are roughly 30-40 K, and the system temperature ranges from 60-150 K depending on the frequency and weather conditions (Zhong et al 2018). The FWHM of the primary beam is ∼30″ at 40 GHz.…”

Section: Tmrtmentioning

confidence: 99%

A Q-band Line Survey toward Orion KL Using the Tianma Radio Telescope

Liu

Shen

Qin

et al. 2022

ApJS

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“…The slew rate is 0.5 • s −1 and 0.3 • s −1 at azimuth and elevation directions respectively. Dual-pixel receivers are installed in TMRT at both 22 and 43 GHz which enables simultaneous observations of multiple lines (Zhong et al 2018). These two beams have a fixed separation angle of 140 arcseconds at 22 GHz and 100 arcseconds at 43 GHz.…”

Section: Tianma 65-m Radio Telescope (Tmrt)mentioning

confidence: 99%

East Asian VLBI Network Observations of Active Galactic Nuclei Jets: Imaging with KaVA+Tianma+Nanshan

Cui,

Hada,

Kino

et al. 2021

Preprint

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The East Asian very-long-baseline interferometry (VLBI) Network (EAVN) is a rapidly evolving international VLBI array that is currently promoted under joint efforts among China, Japan, and Korea. EAVN aims at forming a joint VLBI Network by combining a large number of radio telescopes distributed over East Asian regions. After the combination of the Korean VLBI Network (KVN) and the VLBI Exploration of Radio Astrometry (VERA) into KaVA, further expansion with the joint array in East Asia is actively promoted. Here we report the first imaging results (at 22 and 43 GHz) of bright radio sources obtained with KaVA connected to Tianma 65-m and Nanshan 26-m Radio Telescopes in China. To test the EAVN imaging performance for different sources, we observed four active galactic nuclei (AGN) having different brightness and morphology. As a result, we confirmed that Tianma 65-m Radio Telescope (TMRT) significantly enhances the overall array sensitivity, a factor of 4 improvement in baseline sensitivity and 2 in image dynamic range compared to the case of KaVA only. The addition of Nanshan 26-m Radio Telescope (NSRT) further doubled the east-west angular resolution. With the resulting high-dynamic-range, high-resolution images with EAVN (KaVA+TMRT+NSRT), various fine-scale structures in our targets, such as the counter-jet in M 87, a kink-like morphology of the 3C 273 jet and the weak emission in other sources, are successfully detected. This demonstrates the powerful capability of EAVN to study AGN jets and to achieve other science goals in general. Ongoing expansion of EAVN will further enhance the angular resolution, detection sensitivity and frequency coverage of the network.

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“…The Tianma Radio Telescope (TMRT) is currently the largest fully‐steerable radio telescope in Asia with a diameter of 65 m. The Q‐band two‐beam cryogenic receiver from 35 to 50 GHz on the TMRT requires circular polarizers of high performance such as low insertion losses, high return losses, low cross‐polarization levels, and so on . A polarizer consists of a differential phase shifter and an orthomode transducer (OMT), with the differential phase shifter firstly creating the orthogonal linearly polarized components with a designed phase shift and the OMT then separating the orthogonal linearly polarized signal components …”

Section: Introductionmentioning

confidence: 99%

A Q‐band compact high‐performance double‐ridged orthomode transducer

Zhong

Yin

Shi

2019

Int J RF Microw Comput Aided Eng

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In this article, a Q‐band compact waveguide orthomode transducer (OMT) based on a stepped double‐ridged waveguide is presented. By using a symmetrical structure, good output return losses of above 20 dB are obtained from 35 to 50 GHz. In particular, the measured insertion losses are as low as 0.15 to 0.4 dB over the entire band for both polarization channels with an improved assembly configuration. The measured cross‐polarization levels are well below −37 dB, while the circular‐polarized output port isolation is less than −20 dB combined with a feed horn and a differential phase shifter. The developed OMTs have been used in a Q‐band two‐beam cryogenic receiver on the Tianma Radio Telescope, contributing only 1 to 2 K noise at an operating temperature around 20 K.

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A Q-band two-beam cryogenic receiver for the Tianma Radio Telescope

Cited by 11 publications

References 30 publications

A Q-band Line Survey toward Orion KL Using the Tianma Radio Telescope

A Q-band Line Survey toward Orion KL Using the Tianma Radio Telescope

East Asian VLBI Network Observations of Active Galactic Nuclei Jets: Imaging with KaVA+Tianma+Nanshan

A Q‐band compact high‐performance double‐ridged orthomode transducer

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