SKA1-Low: impact of antenna response and mutual coupling on the off-zenith array pointing

摘要

SKA1-Low is a VHF radio telescope consisting of more than 130.000 dual-polarized antennas grouped in stations of 256 antennas each. Each station will observe the sky within 45 degrees from the local zenith by using an electronic beamforming. The individual pattern of the antenna and the mutual coupling among antennas can be responsible of a degradation in the synthesized station beam. In particular, the combination of those phenomena can produce an offset in the angular pointing and a reduction of the station directivity. A quantitative analysis for the off-zenith pointing is numerically computed for a technological demonstrator of SKA1-Low. Additional results to mitigate the mutual coupling effects are presented at the lower frequency where the phenomenon is more significant.