The characteristics of antenna system in Chinese Spectral Radio heliograph

The Chinese Spectral Radioheliograph (CSRH) is a telescope observing the Sun in radio wavelength on the ground, it uses Eleven antenna as its feed with ultra wide band and dual polarized characteristics. This feed is composed of several folded dipoles arranging in periodic array. In comparison with original Eleven feed, the performance of this feed is largely enhanced through some optimized work. The reflection coefficient of this feed is less than -15dB and the axial ratio is below 1.5dB in 0.4-2GHz. After the feed is installed in the reflector antenna, with the use of different terminals added in front end of the receiver, Y factor method is used to measure the antenna noise temperature. The test results show that the noise temperature of antenna IB1 is less than 120K. The pattern of this Eleven feed is shaped well to the radiation pattern of the reflector antenna. With the use of the simulated radiation patterns of the antenna feed, the measured results of the system temperatures are demonstrated as follows.