One band or two?

1. 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