Implementing a high performance AA-mid in SKA2

Abstract

Aperture phased arrays operating at mid-frequencies from 400MHz to 1.4 GHz are a very exciting receiver technology being developed for the Square Kilometre Array, SKA. In many respects they enable the original concept of the SKA: to survey hydrogen in the universe out to a high redshift. The capabilities of a telescope using phased array stations brings major scientific opportunities, including very high survey speeds, flexibility for searching for transient phenomena, and multi-beaming capability which cannot be realized using any other technology. The very high level of control over each receiver element enables exquisite calibration as a function of frequency and pointing direction. The technological requirements to implement high frequency, astronomically capable phased arrays are severe in terms of power and cost due to the large numbers of channels and the amount of digital processing required. However, technology roadmapping shows that forthcoming technical developments make a large system deployment realistic from 2020 onwards. An aperture array covering this frequency range is the only instrument able to perform some of the most challenging science experiments planned for the SKA and is likely to make transformational discoveries.