The Electromagnetic Characteristics of the Tianlai Cylindrical Pathfinder Array  

作　　者：Shijie Sun Jixia Li Fengquan Wu Peter Timbie Reza Ansari Jingchao Geng Huli Shi Albert Stebbins Yougang Wang Juyong Zhang Xuelei Chen 

机构地区：[1]National Astronomical Observatories,Chinese Academy of Sciences,Beijing 100101,China [2]University of Chinese Academy of Sciences,Beijing 100049,China [3]Department of Physics,University of Wisconsin Madison,1150 University Ave,Madison WI 53703,united States of America [4]IJC Lab,CNRS/IN2P3&UniversitéParis-Saclay,15 rue Georges Clemenceau,F-91405 Orsay,France [5]The 54th Research Institute,China Electronics Technology Group Corporation,Shijiazhuang,Hebei 050051,China [6]Fermi National Accelerator Laboratory,P.O.Box 500,Batavia IL 60510-5011,United States of America [7]School of Mechanical Engineering,Hangzhou Dianzi University,Hangzhou 310017,China [8]Department of Physics,College of Sciences,Northeastern University,Shenyang 110819,China [9]Center of High Energy Physics,Peking University,Beijing 100871,China

出　　处：《Research in Astronomy and Astrophysics》2022年第6期234-255,共22页天文和天体物理学研究（英文版）

基　　金：supported by the Ministry of Science and Technology(MOST)-BRICS Flagship Project 2018YFE0120800;National SKA Program of China No.2020SKA0110401;the National Key R&D Program 2017YFA0402603;the National Natural Science Foundation of China(NSFC,Grant Nos.11973047,11633004 and U1631118);the Chinese Academy of Sciences(CAS)Strategic Priority Research Program XDA15020200;the CAS Frontier Science Key Project QYZDJ–SSW–SLH017;the CAS Inter-disciplinary Innovation Team(JCTD-2019-05);the CAS Key Instruments project ZDKYYQ20200008;the Hebei Key Laboratory of Radio Astronomy Technology(HKLRAT)。

摘　　要：A great challenge for 21 cm intensity mapping experiments is the strong foreground radiation which is orders of magnitude brighter than the 21 cm signal.Removal of the foreground takes advantage of the fact that its frequency spectrum is smooth while the redshifted 21 cm signal spectrum is stochastic.However,a complication is the nonsmoothness of the instrument response.This paper describes the electromagnetic simulation of the Tianlai cylinder array,a pathfinder for 21 cm intensity mapping experiments.Due to the vast scales involved,a direct simulation requires a large amount of computing resources.We have made the simulation practical by using a combination of methods:first simulate a single feed,then an array of feed units,finally with the feed array and a cylindrical reflector together,obtain the response for a single cylinder.We studied its radiation pattern,bandpass response and the effects of mutual coupling between feed units,and compared the results with observation.Many features seen in the measurement result are reproduced well in the simulation,especially the oscillatory features which are associated with the standing waves on the reflector.The mutual coupling between feed units is quantified with Sparameters,which decrease as the distance between the two feeds increases.Based on the simulated S-parameters,we estimate the correlated noise which has been seen in the visibility data,and the results show very good agreement with the data in both magnitude and frequency structures.These results provide useful insights on the problem of 21 cm signal extraction for real instruments.

关 键 词：instrumentation interferometers-methods NUMERICAL-METHODS observational-cosmology observations-(cosmology:)dark ages-reionization-first stars-(cosmology:)diffuse radiation 

分 类 号：P111[天文地球—天文学] P159