One band or two? See SKA Memo 140 for starting point in performance – cost analysis (70-450 MHz) No a priori advantages for either 1 or 2-band with current SKA goals Particular specs and site/operations issues influence relative and absolute costings Tweaks on original analysis: FoV, array configuration etc Processed FoV above ~200 MHz is a major relative cost driver, due b/f With a “relaxed” FoV spec, 1-band array has cost advantage Deployment costs are a significant absolute cost driver for SKA-low Huge number of elemental antennas demands optimized strategy Worrying global indifference to Memo 140 absolute costs Very sparse array at 450 MHz may be a problem for 1-band calibration (sidelobes) May just be OK at 400 MHz Need information from pathfinders Need to be able to pay the calibration power bill ! Push for 50 MHz is growing but no-one wants to give up on high-freq (and some want >450 MHz) We may need 2–bands anyway Frequency coverage and FoV are primary inputs for our design brief Urgent need for science convergence Active role needed for pathfinders to contribute pre-SRR info SKA-low (LFAA) – Peter J Hall