稻城太阳射电望远镜(DSRT)天线遮挡效应仿真

稻城太阳射电望远镜（DSRT）由313面6 m直径抛物面天线组成。天线接收信号幅值和相位的精确修正是决定DSRT成像质量的关键因素。然而DSRT阵列可能会出现邻近天线相互遮挡的问题，从而改变接收信号的幅值和相位，影响其成像质量。利用电磁仿真软件计算了接收频率为300 MHz（波长λ=1 m）时的相邻两单元与相邻三单元两种情况。三元系统中遮挡效应的影响仅比双元系统中相关影响略为显著。在本文考虑的最严重的遮挡情况（天线边缘的投影间距D = –1λ）下，对于双/三元系统，相对于单天线系统水平和垂直增益分别降低了0.6/0.6 dB和 0.3/0.4 dB，相位偏差分别为–3.3º/–3.871º和–1.744º/–2.244º。此外还分析了其他遮挡情况。研究表明DSRT系统中的天线遮挡效应分析可由双元系统充分描述，在后期数据处理时应适当考虑该效应，尽量提升DSRT数据的利用效率和成图质量。

Simulations of the Antenna-shielding Effect of the Daocheng Solar Radio Telescope (DSRT)

The Daocheng Solar Radio Telescope (DSRT) is a next-generation solar radio telescope funded by the Chinese Meridian Project–Phase II. DSRT is composed of 313 parabolic antennas with a diameter of six meters. The antennas are evenly distributed in a circle with a diameter of one kilometer. With the synthetic aperture imaging techniques, key factors determining the DSRT imaging quality are accurate calibrations of amplitude and phase of the received signals. Yet, under some circumstances, adjacent antennas of DSRT may shield each other, which will affects the amplitude and phase of the received signals and thus deteriorate imaging quality. In this study, such shielding effects of three- or two-antenna using the electromagnetic simulation software at frequencies of 300 MHz (λ=1 m) were simulated. The shielding effect in the three-antenna system is slightly worse than that in the two-antenna system. When the projected distance of adjacent antennas is taken to be –1λ, i.e., the most serious effect of shielding considered here, the horizontal and vertical gains of the system with two/three antennas decline by 0.6/0.6 dB and 0.3/0.4 dB, respectively, and the horizontal and vertical phase deviations are –3.3º/–3.871º and –1.744º/–2.244º, respectively, compared to the system with one antenna. Other situations with different projected shielding distances are also investigated. The results show that the two-antenna system can sufficiently describe the shielding effect associated with DSRT. Such effect should be properly taken into account when processing the future DSRT data so as to improve the data usage efficiency and imaging quality.