Experimental results of the APERTIF phased array feed

APERTIF (APERture Tile In Focus) is a Phased Array Feed (PAF) system that is being developed for the Westerbork Synthesis Radio Telescope (WSRT) to increase its survey speed with a factor 20. This paper presents an overview of APERTIF and measurement results that demonstrate the unique capabilities of PAFs in practice: Wide field of view (scan range), low system temperature, excellent illumination efficiency, synthesis imaging and a significant reduction of the reflector feed interaction.