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.
引文
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(1)http://www.evlbi.org/tog/ftp_fringes/N17L2/scan02/index.html