Phased Array Feeds for the SKA. WP2.2.3 PAFSKA Consortium CSIRO ASTRON DRAO NRAO BYU OdP Nancay Cornell U Manchester

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1 Phased Array Feeds for the SKA WP2.2.3 PAFSKA Consortium CSIRO ASTRON DRAO NRAO BYU OdP Nancay Cornell U Manchester

2 Dish Array Hierarchy Dish Array L5 Elements PAF Dish Single Pixel Feeds L4 Sub systems PAF Feed Payload PAF Receiver L3 assemblies PAF Array/ Low-noise amplifiers PAF Receiver Package RF electronics Digital electronics L2 Sub assemblies

3 PAFs in development 2011 National Radio Astronomy Observatory

4 PAFSKA Developing PAFs for the SKA Collaborative program of Phased Array Feed R&D for the SKA. Many institutes; each focussing on one or more aspects of PAFs Individual institutes have long-standing PAF development projects. PAFSKA commenced mid-2010; PAF PrepSKA tasks completed -> WP2.2 Dish Array CoDR Based on the PAF-specific PrepSKA work packages + whole-system developments ASKAP and APERTIF. Ultimate goal of delivering a PAF which meets the total SKA specification: technical performance, operational performance and cost. Developing L band PAFs with system adaptable to adjacent frequencies

5 PAF development Critical aspect is for the PAF to be affordable, manufacturable and maintainable;.a new challenge for the community and applicable to all components of SKA SKA PEP WP5 Dish Array EUR 15.3M Dish EUR 3.4 M OBSPF EUR 1.4 M PAF EUR 7.9 M WBSPF EUR 0.9 M

6 PAFs in SKA? SKA2: Concept to early definition

7 SKA 1 Design Concept Sparse Aperture Array SKA1 Baseline Sparse AA SPF1 SPF2 70 MHz GHz 20 GHz GHz 1-2 GHz (memo 130) 450 MHz challenge for all dish-based receivers large! (2x AA low band extend > 450 MHz?)

8 SKA 1 Design Concept Sparse Aperture Array SKA1 Baseline Sparse AA SPF1 SPF2 70 MHz GHz 20 GHz GHz 1-2 GHz (memo 130) SKA1 with PAFs Sparse AA PAF 70 MHz GHz 20 GHz GHz

9 SKA 1 Design Concept Sparse Aperture Array SKA1 with PAFs Sparse AA PAF1 PAF 2 70 MHz GHz 20 GHz GHz GHz

10 SKA 1 Design Concept Sparse Aperture Array SKA1 with PAFs Sparse AA PAF1 PAF 2 70 MHz GHz 20 GHz GHz GHz (memo 130) SKA2 with PAFs? Sparse AA PAF1 PAF2 PAF3 PAF4 70 MHz GHz 20 GHz GHz GHz

11 CoDR PAF Receiver Concepts

12 PAF sub-system overview PAF presentations at Dish Array CoDR, Penticton July 2011 Optics PAF SKA Context, addressing SKA requirements PAF concept PAF design (optics) feeds & LNA PAF Concept PAF Receiver systems PAF requirements, risks and logistics at the SKA scale PAF Costs & plans for next phase ALL PUBLIC DOCUMENTS all on wiki

13 PAFs in development 2011 National Radio Astronomy Observatory

14 APERTIF developments 2011 Measured sensitivity over the field of view at 3 frequencies 1009 MHz 1416 MHz 1613 MHz Design (manufacturing) studies

15 APERTIF Experimental results APERTIF prototype simultaneously observed pulsars 7 full moons apart B (right) and B (left) 3.8 deg

16 ASKAP PAF developments CSIRO. ASKAP PAF development update July 12, 2011

17 ASKAP PAF developments CSIRO. ASKAP PAF development update July 12, 2011

18 Aperture-Plane Array T sys (PAF) CSIRO. ASKAP PAF development update July 12, 2011

19 (ASKAP) PAF FoV de-rotation Front-fed single reflector 3 rd axis has been done (ASKAP) Offset-fed dual reflector 3 rd axis is more difficult Electronic beam scan tertiary pattern must retain shape primary and secondary spillover will rotate wrt sources, so must be small primary (PAF) tertiary secondary

20 NRC-Canada: Phased-Array Feed Demonstrator (PHAD) 180-element Vivaldi array Dual polarized 1 2 GHz Off-line beamforming Tested on 10-m dish Engineering demonstrator Modular construction High Tsys Narrow band and slow beamformer Results published: Veidt et al., Demonstration of a Dual-Polarized Phased- Array Feed, IEEE Trans. Antennas and Propagation, vol. 59, pp , 2011

21 NRC-Canada: Advanced Focal Array Demonstrator (AFAD) Goal: Astronomy-capable demonstrator GHz Reduce Tsys Use thick metallic low-loss structures Embed LNA at feed point Increase bandwidth Direct sampling at 3 GS/s Filtering and frequency conversion performed in digital domain 0.5 GHz bandwidth per element

22 PAF Developments at BYU/NRAO 19 element single polarization active impedance matched array (2010) On Arecibo and Green Bank 20m telescopes 19 x 2 element dual-polarized array (2010) Cryogenic 19 x 2 PAF (2011) Elements: David Carter, BYU Dewar: Roger Norrod, NRAO LNAs: Sander Weinreb, Caltech Back end: Anish Roshi, NRAO

23 University of Manchester - ORA David Zhang & Tony Brown (et al); Octagonal Ring Antenna (patented) Series of aperture array options investigated; also applicable to planar PAFs ORA can be optimised as single-ended or differential fed

24 PAF Dish Array CoDR documentation A. The requirements specification, propagated from the top-level SKA requirements: 1. PAF sub-system requirements: WP RS-001-A B. The description of the technologies 2. PAF sub-system concept WP TD-001-A 3. PAF feed payload concept: WP TD-001-A Planar & 3D (Vivaldi) types 4. PAF receiver concept RF-over-fibre: WP TD-001-A 5. PAF receiver concept I/Q mixer: WP TD-002-A 6. PAF receiver concept full band sampling: WP TD-003-A -SKA_2 C. Supporting documentation 7. PAF sub-system risk register: WP RE-001-A 8. PAF sub-system Strategy & Plans for next phase: WP PLA-001-A 9. PAF sub-system Cost estimates: WP TD-002-A - Costed feed to pre-correlator system 10. PAF sub-system Logistics Engineering: WP MP-001-A 11. PAF sub-system Software description: WP SD-001-A 12. PAF sub-system Technology roadmap: WP TD-003-A

25 PAF sub-system overview Optics, Dish Narrowing of options during development of SKA SKA1 ready SKA2 ready

26 PAF sub-system overview Optics, Dish Multiple potential Element types Receiver designs Digital systems

27 PAF sub-system overview Optics, Dish Analyse element type performance Feed design & integration SKA1: Receiver development RFoF/I-Q SKA2: Receiver development Direct sampling

28 PAF sub-system overview Optics, Dish Element type selection Feed design & integration prototype SKA1: Receiver development RFoF/I-Q SKA2: Receiver development Direct sampling

29 PAFs cost estimates (SKA1) PAF sub-system based on RF-over-Fibre with multi-band direct sampling. Start with established PAF build costs (2009 designs) - small N systems; non-optimised; RF over coax; from PAFSKA 3 steps to a 2014-build PAF cost estimate: Step A. Estimate the cost for PAF RFoF today (2011), Step B. Review the feed payload design optimisations, move from proof of concept feed array to smart design-for-build (first-level cost reduction), Step C. Consider further refinements and component cost reductions expected by 2014 (refine cost-per-build) Baseline for costing: assuming a GHz PAF (scalable) 200 elements (dual-pol, any element type), 400 MHz bandwidth, 36 beams

30 PAFs at SKA CoDR Stage PAFs and Dish Design options ASKAP PAF on 12-m axi-symmetric dish (highly optimised for survey speed), RFoF APERTIF on 25m WRST equatorial symmetric dish DRAO PHAD/AFAD direct sampling prototyping

31 PAFs at SKA CoDR Stage ASKAP PAF on 12-m axi-symmetric dish APERTIF on 25m WRST equatorial symmetric dish DRAO PHAD/AFAD direct sampling prototyping APERTIF & ASKAP are PAF SKA pathfinders. Plus expertise from PAFSKA Critical lessons for SKA: 1. Need to optimise dish-feed design, and not build-out flexibility re feeds 2. Optimised for survey speed demonstrate PAF flexibility (DR, FoV etc) 3. Advantages of a sky-mount axis (DR,.for any feed type?) 4. Full system builds (far better than single prototypes or paper-based design concepts) 5. Develop & test calibration, imaging, etc schemes to be well understood in time for SKA 6. Astronomers will learn to expect PAF performance & flexibility on the SKA Wide FoV is not a pieced-together mosaic; it is a singly-imaged flat field.

32 PAFs for SKA 1. Powerful and flexible feed option for SKA 2. PAF enables wide-field surveys on viable timescales; -> also capable of meeting SKA dynamic range & polarisation purity spec etc. 3. Established technology; identified the key refinements during PEP phase (next phase planning is well progressed; expertise available) 4. Ready for SKA1; PAFs for high frequency for SKA2 5. Array test-bed(s) available now, ahead of the PEP. 6. Major institutional commitment to demonstrate astronomy-ready PAF arrays (ASTRON & CSIRO) 7. PAFSKA continues as collaborative pool of international expertise with productive, annual meetings (extending beyond PEP participants)

33 CSIRO Astronomy and Space Science Dr Carole Jackson Phone: Carole.Jackson@csiro.au Web: