新疆天文台26米望远镜L波段接收机线-圆偏振的转换
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摘要
新疆天文台南山基地26 m射电望远镜L波段接收机使用线偏振馈源接收电磁波信号用于脉冲星观测。分子谱线观测和VLBI国际联测需要圆偏振信号,因此希望接收机能够观测圆偏振信号。论述了将线偏振电磁波转换为圆偏振电磁波的方案,研究了90~°电桥在偏振转换中的作用,介绍了偏振转换的调试方法。在圆偏振模块中使用90~°电桥完成线偏振信号到圆偏振信号的转换,两路圆偏振信号的隔离度达到使用要求,满足圆偏振观测的需求。这种线偏振信号到圆偏振信号的转换方式不影响接收机的系统温度。
The L-band receiver can be used for pulsar observation, molecular line observation and international VLBI joint-observations of the 26-meter telescope at Nanshan in Xinjiang Astronomical Observatory, Chinese Academy of Sciences. The L-band receiver is mainly developed for pulsar observations, which outputs linear polarization signals. Circular polarization signals are required in molecular line observation and the international VLBI joint observations. We hope that the L-band receiver can be used for both linear polarization signal observation and circular polarization signal observation, so a polarization conversion device is used to convert the linearly polarized signal to the circularly polarized signal in the L-band receiver. The isolation between right-hand circular polarization signal and left-hand circular polarization signal must be large enough in the converting process. In this paper, a 90~° Hybrid Coupler is used and its role in the conversion is studied, and the converting method is realized. The isolation of the two circular polarization signals meets the requirements of the subjects, both types of signals can be used in circular polarization observation.
The L-band receiver can be used for pulsar observation, molecular line observation and international VLBI joint-observations of the 26-meter telescope at Nanshan in Xinjiang Astronomical Observatory, Chinese Academy of Sciences. The L-band receiver is mainly developed for pulsar observations, which outputs linear polarization signals. Circular polarization signals are required in molecular line observation and the international VLBI joint observations. We hope that the L-band receiver can be used for both linear polarization signal observation and circular polarization signal observation, so a polarization conversion device is used to convert the linearly polarized signal to the circularly polarized signal in the L-band receiver. The isolation between right-hand circular polarization signal and left-hand circular polarization signal must be large enough in the converting process. In this paper, a 90~° Hybrid Coupler is used and its role in the conversion is studied, and the converting method is realized. The isolation of the two circular polarization signals meets the requirements of the subjects, both types of signals can be used in circular polarization observation.
引文
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(1)http://www.evlbi.org/tog/ftp_fringes/N17L2/scan02/index.html
[2] 贾茹,李斌.天马望远镜Ka波段宽带圆极化器研制[J].天文研究与技术,2017,14(4):488-494.
[3] 王海伦,李斌.K波段宽带圆极化器设计[J].天文研究与技术,2015,12(4):455-460.
[4] 周德丽.基于FAST数字终端的线-圆偏振转换的研究[J].电子技术与软件工程,2018(4):97-98.
[5] 陈松麟.ADS辅助实现线极化到圆极化的转换[J].中国科学院上海天文台年刊,2005(26):103-109.
[6] 苑婷婷,史俊,仲伟业,等.Q波段宽带圆极化器设计与研究[J].中国科学院上海天文台年刊,2014(35):41-50.
[7] 王锦清,仲伟业.上海65m射电望远镜 Ka波段极化器设计[J] .中国科学院上海天文台年刊,2009(30):39-50.
[8] 冯亚伯.电磁场理论[M].成都:电子科技大学出版社,1995.
[9] POZAR D M.微波工程[M].3版.张肇仪,周乐柱,吴德明,译.北京:电子工业出版社,2006.
[10] 廖承恩.微波技术基础[M] .西安:西安电子科技大学出版社,1995.
(1)http://www.evlbi.org/tog/ftp_fringes/N17L2/scan02/index.html