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arXiv · 2504.04955

The Short-spacing Interferometer Array for Global 21-cm Signal Detection (SIGMA): Design of the Antennas and Layout

Feiyu Zhao·Quan Guo·Qian Zheng·Ruxi Liang·Pengfei Zhang·Yajun Wu·Junhua Gu·Zhao Yang·Yun Yu·Yan Huang·Tianyang Liu
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Abstract

Numerous experiments have been designed to investigate the Cosmic Dawn (CD) and Epoch of Reionization (EoR) by examining redshifted 21-cm emissions from neutral hydrogen. Detecting the global spectrum of redshifted 21-cm signals is typically achieved through single-antenna experiments. However, this global 21-cm signal is deeply embedded in foreground emissions, which are about four orders of magnitude stronger. Extracting this faint signal is a significant challenge, requiring highly precise instrumental calibration. Additionally, accurately modelling receiver noise in single-antenna experiments is inherently complex. An alternative approach using a short-spacing interferometer is expected to alleviate these difficulties because the noise in different receivers is uncorrelated and averages to zero upon cross-correlation. The Short-spacing Interferometer array for Global 21-cm Signal detection (SIGMA) is an upcoming experiment aimed at detecting the global CD/EoR signal using this approach. We describe the SIGMA system with a focus on optimal antenna design and layout, and propose a framework to address cross-talk between antennas in future calibrations. The SIGMA system is intended to serve as a prototype to gain a better understanding of the system's instrumental effects and to optimize its performance further.

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Feiyu Zhao, Quan Guo, Qian Zheng, Ruxi Liang, Pengfei Zhang, Yajun Wu, Junhua Gu, Zhao Yang, Yun Yu, Yan Huang, Tianyang Liu. 2025-04-07. The Short-spacing Interferometer Array for Global 21-cm Signal Detection (SIGMA): Design of the Antennas and Layout. https://arxiv.org/abs/2504.04955

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