Design of An Analog Receiver for Solar Radio Observation in the Frequency Range of 30MHz to 65MHz

Solar radio radiations mainly come from the corona of the sun, and radio waves in different bands reflect activities in different layers of the corona. Observational studies about solar radio radiations are among the most important approaches to derive physical-parameter values of the corona (e.g., temperature, density, and magnetic-field strength). Decimeter waves come from a corona layer of heights approximately 1 to 2 times of the solar radius above the solar surface, which makes solar radio observations in decimeter waves particularly important in the coronal physics. For example, such studies can be used to monitor propagations of CME (Coronal Mass Ejection) and shock waves in high layers of the corona, and to forecast space weather. Currently, there is a lack of solar radio observations in decimeter waves in China. It is urgent to build Chinese decimeter-wave solar radio telescopes and associated key equipments. A solar radio antenna array working in low-frequency bands has been built in the YNAO (Yunnan Observatories). The array consists of four antennas. It will work with the YNAO 10m solar radio telescope (working in the frequency range of 625MHz to 1500MHz) and 11m solar radio telescope (working in the frequency range of 70MHz to 700MHz), achieving a complete wavelength coverage of coronal radio observation. In this paper we introduce our design of an analog receiver to be installed in the solar radio antenna array of the YNAO. The receiver is to monitor solar radio bursts in decimeter wavelengths corresponding to the frequency range of 30MHz to 65MHz. The analog receiver consists of Baluns, filters, and amplifiers for direct sampling. The performance parameters of the analog receiver meet the requirements for observations: The gain reaches 60dB, the dynamic range is about 33dB, the input third-order intercept point is about -24dBm, and the noise figure is about 4.3dB. We finally calculate the sensitivity limits of the solar radio antenna array with the analog receiver installed.