Phased array antenna design and characterization for next-generation radio telescopes

Instrumentation for radio astronomical observations is currently undergoing a transition from large reflectors with single-pixel feeds to multi-pixel phased arrays. Research efforts aimed at realizing the benefits of phased arrays for highly sensitive, calibrated astronomical measurements have opened up interesting challenges for antenna designers. This paper surveys recent theoretical and experimental results on characterization of beam equivalent noise temperature and efficiency, impedance matching to minimize front end noise, and beamforming and calibration algorithms for phased array feeds.