  We describe a Phased Array Feed (PAF) system, called Apertif, which will be
installed in the Westerbork Synthesis Radio Telescope (WSRT). The aim of
Apertif is, at frequencies from 1.0 to 1.7 GHz, to increase the instantaneous
field of view of the WSRT 8 deg^2 and its observing bandwidth to 300 MHz with
high spectral resolution. This system will turn the WSRT into an effective
survey telescope with scientific applications ranging from deep surveys of the
northern sky of HI and OH emission and polarised continuum to efficient
searches for pulsars and transients. We present results obtained with a
prototype PAF installed in one of the WSRT dishes. These results demonstrate
that at decimetre wavelengths PAFs have excellent performance and that even for
a single beam on the sky they outperform single feed radio dishes. PAFs turn
radio telescopes into very effective survey instruments. Apertif is now fully
funded and the community is invited to express their interest in using Apertif
(http://www.astron.nl/radio-observatory/call-expressions-interest-apertif-surveys
)
