共查询到12条相似文献,搜索用时 62 毫秒
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本文介绍了高空间分辨率的太阳射电观测流量的归算方法,即对观测的太阳天线温度值作天线功率方向图K因子的修正,即可得到太阳射电流量值.文中推导了不同温度分布模型下的K因子表达式,并计算了日面宁静太阳流量值和部分射电源的SVC辐射流量值.对日面宁静区的射电辐射而言,因K的年变化(0.0236—0.0252)不大,因此按其平均值0.0244可计算出22GHz频率上宁静太阳流量s。=0.15Ta。(以sfu为单位,Ta。是宁静区辐射的太阳天线温度),相应的宁静太阳温度为10100土300K.1990年7月2日源区的SVC辐射计算结果表明:日面源区的SVC辐射总和为20sfu,约占日面总辐射的2.4%. 相似文献
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An effective wide-band (10 to 60 MHz) active antenna element has been developed. The cost of one short (3 m), thin dipole with built-in amplifier and metal construction is less than 45 euro. It was shown both theoretically and experimentally that the upper limiting frequency is at least 60 MHz, the dynamic range is 90 dB/V and the share of the amplifier noise to the background antenna temperature is about 10%. The developed active dipole was tested by building a 30-element antenna array and comparing its parameters with one of the subpart of the UTR-2 radio telescope having passive dipoles of 8.6 m in length and 1.8 m in diameter. The 3C461 ionospheric scintillation spectra observed in the experiments show that the sensitivities and noise-immunities of both antennas are close. This proves the availability using of a short cheap active dipole in new generation giant radio telescopes. 相似文献
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C. R. SUBRAHMANYA P. PRASAD B. S. GIRISH R. SOMASHEKAR P. K. MANOHARAN A. K. MITTAL 《Journal of Astrophysics and Astronomy》2017,38(1):11
The legacy Ooty Radio Telescope (ORT) is being reconfigured as a 264-element synthesis telescope, called the Ooty Wide Field Array (OWFA). Its antenna elements are the contiguous 1.92 m sections of the parabolic cylinder. It will operate in a 38-MHz frequency band centred at 326.5 MHz and will be equipped with a digital receiver including a 264-element spectral correlator with a spectral resolution of 48 kHz. OWFA is designed to retain the benefits of equatorial mount, continuous 9-hour tracking ability and large collecting area of the legacy telescope and use of modern digital techniques to enhance the instantaneous field-of-view by more than an order of magnitude. OWFA has unique advantages for contemporary investigations related to large scale structure, transient events and space weather watch. In this paper, we describe the RF subsystems, digitizers and fibre optic communication of OWFA and highlight some specific aspects of the system relevant for the observations planned during the initial operation. 相似文献
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Kai Wang Liang Cao Jun Ma Xue-Feng Duan Hao Yan Mao-Zheng Chen Yun-Wei Ning 《天文和天体物理学研究(英文版)》2024,(4):62-72
The receiver is a signal receiving device placed at the focus of the telescope. In order to improve the observation efficiency, the concept of phased array receiver has been proposed in recent years, which places a small phased array at the focal plane of the reflector, and flexible pattern and beam scanning functions can be achieved through a beamforming network. If combined with the element multiplexing, all beams within the entire field of view can be observed simultaneously to achieve contin... 相似文献
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GPS接收机天线相位中心偏差的检测 总被引:5,自引:0,他引:5
GPS接收机天线相位中心偏差是指GPS天线接收卫星信号的电气中心与基机械几何中心之差。在高精度测量中,这是不容忽视的。讨论了采用基线测量相对测定法确定天线相位中心在水平和垂直方向上的偏差的原理和方法,并给出了测量结果及建议。 相似文献
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以新月时月亮的射电辐射为温度基准和准口面温度定标的方法,在22GHz频率上于1993年7月~3月测量了13.7m射电望远镜抛物面天线的增益。根据测量的增益值(67.10─±0.07db)定标了太阳射电流量,流量测量的系统差为±5.8%,偶然差为±2.7%,测量的宁静太阳亮温度(非源区)为10100±300K。除此之外,还推导和计算了不同源模型下的天线方向图改正因子Ks,并计算了太阳射电源的流量密度。 相似文献
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本文介绍了用四种定标基准ΔTc=(T0-TL),(TH-T0),(T0-TANz)和(T0-THNz),并用射电源作为校准测量微波天线增益的基本原理和方法。并对四种不同类型的天线增益进行了测量,测量结果表明,以ΔTc=(T0-THNz)和总功率辐射计所组成的测量系统可实施增益的高精度测量。测量设备可以和接收系统兼容,不需专用测量设备,因此该技术可在工程中广泛使用。 相似文献