Advances in phased array systems for radio astronomy

Phased array antenna systems are a defining technology in many current and planned radio astronomical instruments. Phased array technology enables new observing modes due to their large field-of-view, multi-beaming capability and rapid response. The radio astronomical application provides interesting challenges such as stringent requirements on system temperature and system calibration. In this paper, we discuss the motivation for using phased array systems in radio astronomy and provide an overview of recent advances and results in this area.