SKA low frequency aperture array design

A design for a very large, 250,000 antenna, aperture array covering 50-650MHz is discussed here. This is one of the major developments for Phase 1 of the Square Kilometre Array radio telescope, to be deployed between 2017 and 2019. Essential to the efficient design of the array are a single very wide-bandwidth log-periodic antenna and low cost, medium range RF over fibre system. This results in a system design that can have minimal electronics at the antenna and all the digital processing for the entire array in a single, large processing “bunker”. This is very cost effective, flexible in configuration and easiest operationally for ongoing maintenance. Further, there is the opportunity to house other parts of the SKA-low telescope: e.g. correlator, master clock, telescope management and post processing facilities. The aim is to have individual solar powered antennas to minimize interference issues and save infrastructure costs. The beamforming will be entirely in the digital domain using devices predicted for 2017/8. Considerable flexibility is given by the innovative use of high speed commercial data switches, which enables selectable station sizes and tuning for specific science experiments. The entire system uses technologies that are available or projected in the near future.