Study of Very Low Frequency Solar Radio Emission Detection with Space Vector Antenna
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摘要: 目前已有空间探测器对太阳的甚低频射电爆发进行的探测主要是频谱观测,且仅覆盖甚低频频段中的很小一部分,针对太阳低频射电爆发的成像观测仍然是空白。基于空间矢量天线的特性,它可以实现对空间来波信号的达波方向进行估计。利用它可以对太阳低频射电爆发(包括Ⅱ型和Ⅲ型暴)进行空间定位和一定的成像观测。本研究针对空间(甚)低频射电探测器对太阳射电爆发的探测,提出了利用三极子矢量天线对太阳爆发进行定位的算法,并基于部分空间甚低频设备的观测数据,在不同条件下对算法进行了仿真,同时针对“嫦娥4号”上的甚低频射电探测器(同样采用了三极子矢量天线),分析了其探测太阳低频射电爆发的能力。结果表明:当信号的信噪比达到10 dB以上时,矢量天线可以实现度量级的定位精度;并进一步分析了空间低频探测器探测太阳低频射电爆发的能力。Abstract: Solar winds, coronal mass ejections(CME), interplanetary shock waves and high-energy particle events, induced by the solar radio bursts, are called as solar electromagnetic storms. The propagation, acceleration, and evolution of the CMEs, solar winds, interplanetary shock waves and high-energy particle phenomena mainly happen at the frequency range from tens of KHz to tens of MHz, which is generally considered as the frequency band of very low frequency(VLF). Though, there are already few space instruments that have investigated the VLF solar radio emissions, most of the observations are spectral measurements, and only occupied part of the whole VLF band, while the imaging observations of the VLF solar radio bursts are still blank. Based on the characteristics of the vector antenna, it can estimate the direction of arrival(DOA)of the incoming waves, which can be used to locate and image the solar radio bursts(Type Ⅱ&Ⅲ). So all the latest space VLF radio instruments adopt the tripole antenna can do the observations. In this paper, in order to investigate the detection of the solar radio bursts with the space VLF radio explorer, different algorithms are proposed to detect the solar radio bursts with a tripole vector antenna, and simulations have been done with some space VLF radio observations for these algorithms under different conditions. The simulation results show that the vector antenna can locate the radio bursts with a degree-level accuracy. The capability of detecting the solar radio bursts is also analyzed in further for the space VLF radio explorer.
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Key words:
- very low frequency /
- space explorer /
- solar radio burst /
- vector antenna
Highlights● Using the characteristic of Tripole vector antenna,how to locate the solar VLF radio burst with single tripole antenna is studied. ● The DOA estimation algorithm is proposed for the tripole antenna,and simulations under different conditions show that it can locate the solar radio burst with a degree-level accuracy under certain SNR. ● The capability of detecting solar radio burst is studied for the VLF radio instrument onboard Chane’e-4 mission. -
表 1 不同信噪比下的DOA估计误差
Table 1 DOA estimation errors for different SNR
DOA估计误差/dB DOA 方位角 /(°) 俯仰角 /(°) 信噪比 5 4.189 9 2.835 6 10 1.812 8 1.421 3 20 0.651 9 0.632 1 30 0.347 8 0.262 7 表 2 不同频率的DOA估计误差
Table 2 DOA estimation errors for different frequencies
DOA估计误差/MHz DOA 方位角 /(°) 俯仰角 /(°) 频率 10 1.488 2 0.972 6 20 1.212 2 0.716 7 30 1.053 2 0.712 0 40 1.417 8 0.783 2 -
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