The visibilities measured by radio astronomical interferometers include non-astronomical correlated signals that arise from the local environment of the array. These correlated signals are especially important in compact arrays such as those under development for 21\,cm intensity mapping. The amplitudes of the contaminated visibilities can exceed the expected 21\,cm signal and represent a significant systematic effect. We study the receiver noise radiated by antennas in compact arrays and develop a model for how it couples to other antennas. We apply the model to the Tianlai Dish Pathfinder Array (TDPA), a compact array of 16, 6-m dish antennas. The coupling model includes electromagnetic simulations, measurements with a network analyzer, and measurements of the noise of the receivers. We compare the model to drift-scan observations with the array and set requirements on the level of antenna cross-coupling for 21\,cm intensity mapping instruments. We find that for the TDPA, cross-coupling would have to be reduced by TBD orders of magnitude in order to contribute negligibly to the visibilities.
Measurement of the Primary Beam of the Tianlai Cylindrical Antenna Using an Unmanned Aerial Vehicle
National Astronomical Observatories, Chinese Academy of Sciences（中国科学院国家天文台）；State Key Laboratory of Radio Astronomy and Technology（射电天文技术国家重点实验室）；School of Astronomy and Space Science, University of Chinese Academy of Sciences（中国科学院大学天文与空间科学学院）
Beamforming in Interferometer Arrays with Cross-couplings
National Astronomical Observatories, Chinese Academy of Sciences（中国科学院国家天文台）；University of Chinese Academy of Sciences（中国科学院大学）；Key Laboratory of Radio Astronomy and Technology, Chinese Academy of Science（中国科学院射电天文与技术重点实验室）；School of Physics and Astronomy, Sun Yat-Sen University（中山大学物理学院）
Overview of the Canadian Hydrogen Observatory and Radio Transient Detector (CHORD) Project
West Virginia University（西弗吉尼亚大学）；University of Calgary（卡尔加里大学）；McGill University（麦吉尔大学）；INAF – Istituto di Radioastronomia（意大利国家天体物理研究所射电天文研究所）；Rhodes University（罗德斯大学）；South African Radio Astronomy Observatory（南非射电天文台）；Queen’s University（女王大学）；University of British Columbia, Okanagan Campus（不列颠哥伦比亚大学奥肯那根校区）；Dunlap Institute for Astronomy & Astrophysics, University of Toronto（多伦多大学邓普天文学与天体物理学研究所）；David A. Dunlap Department of Astronomy & Astrophysics, University of Toronto（多伦多大学大卫·A·邓普克天文学与天体物理学系）；Arizona State University（亚利桑那州立大学）；Anton Pannekoek Institute for Astronomy, University of Amsterdam（阿姆斯特丹大学安东·潘内库克天文学研究所）；ASTRON, Netherlands Institute for Radio Astronomy（荷兰射电天文研究所ASTRON）
