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4-11-2010 1SKA Station Design

AA-mid antenna element initial design

The Advanced Instrumentation Program in the SKA Aperture Array system

SKA WP2 Meeting at Oxford UKOctober 28, 2010

Johan Pragt, ASTRONon behalf of the AAVP team

Contributions from: Dion Kant, Mark Ruiter, Raymond van den Brink, Pieter Benthem,

Hiddo Hanenburg, Eric v.d.Wal, e.a.

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Topics

• Scope of this talk is limited to AA-mid antenna

• AA-mid antenna technical progress– EMBRACE cost evaluation

– Passive Cooling

– LNA concept changes

– RF-connection lines, main board

– Foil and Foam technology

– Other techniques

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AA-Mid Antenna definition focus in this talk

..

Sparse AA

Dense AA

..

Mass Storage

TimeStandard

Central Processing Facility - CPF

User interfacevia Internet

...

To 250 AA Stations

...

DSP

...

DSP

To 1200 Dishes

...

12-15m Dishes

Co

rrelator –

AA

& D

ish

16 Tb/s

80 Gb/s

Control Processors

& User interface

Post Processor

Data

Time

Control

70-450 MHzWide FoV

0.4-1.4 GHzWide FoV

1.0-10 GHzSingle Pixel

Tile &Station

Processing

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AA-mid organization, Timeline

AAVS2 AAlow

Sub-system

2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023

AAVS1 AAlow

demonstrator

construction,

commissioning &

shared-risk obs.

AAVS1 AAmid

Key technol.

demonstrated

detailed design &

pre-construction

1nd gen. instr.

construction,

commissioning &

shared-risk obs.

SKA1 science operations

Q1 2015

Milestone

AAVS2 AAmid

Multiple station

Q1 2013

Milestone

detailed design & pre-constr.1nd gen.

Match with SKA schedule,

SPDO plans

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BFC

13%

Other

9%

Center-board

9%

Sub Frame 8%

Feed-board 8%

profile 3%

Hex-board

39%

Coax 2%

Antenna 9%

assembly 5%

Test setup 4%

EMBRACE cost evaluation

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Embrace Cost Evaluation

• Control on cost drivers. By modifications and changes in:

• Design

• Assembly, Integration

• Reduction of type of parts

• Part cost and purchase

• production process.

• Main part is in electronics

But: mechanics, assembly, testing should reduce proportional

• Functional key components: antenna, LNA, signal distribution, beamforming. Rest is support. Keep 70/30 share.

• Re use developments and knowledge from:LOFAR HBA,EMBRACEAPERTIF2PAD, FLOWPAD

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Specifications AAVS2 AAmid• Technical specs

– Frequency range: 400 MHz - 1421 MHz

– Polarisation: Dual polarisation (Linear)

– Physical Collecting Area: ~2000 m2

– Aeff / Tsys: 40 m2/K

– Electronic scan range: +-45 deg

– Tsys: <50K @ 1GHz

– Nr. of analog beams: 1

– Instantaneous Array Bandwidth: 100 MHz

– Dynamic range A/D Converter: 8bits max (designed for low RFI environment)

– FOV: 108 sq. degr.

(Derived from DS8_T1: Aperture Arrays for the SKA, Rev.0.1, 1 Feb 2010, Sources:SKADS white paper DS8T1R0.91, DoWR0.9)

• Cost goals AAmid Antenna (extrapolated to SKA size and wavelength, today's knowledge):– For the AAVS1 AAmid antenna a cost of 1500 euro as goal.

– Design for AAVS2 AAmid antenna at level of <1000 euro/m2 AA-mid antenna.

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Passive Cooling

• Validation of thermal simulation,

• sun radiation input load for different materials.

• Radiation output load of the materials

• Develop passive cooling concepts, using ground as thermal mass

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LOFAR HBA, 20000 M2

Europe

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Aluminum Large Plates

4-11-2010 10SKA Station Design

Multiple vivaldi antennas in one sheet

LNA close to pick-up point

Plastic support to keep tops in place

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Aluminum Large Plates

4-11-2010 11SKA Station Design

Metal-Metal joining by clinching

Assembled together laying down or standing up

Also expandable (connectable) in other direction

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Application in APERTIF1 M2 on dish of 25 M = 200 M2 (effect.)

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Aluminum Large Plates

4-11-2010 SKA Station Design 13

Signal transmission through small (cheap) PCBs.

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EMBRACE, 170 M2

Netherlands, France

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Aluminum Large Plates

4-11-2010 SKA Station Design 15

Vacuum formed “tile” bottom for six modules

(approx. 1.5 x 2m)

Shape to fit poles

Placement in field by forklift or crane, like

LOFAR HBA.

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Aluminium Plates Station

4-11-2010 SKA Station Design 16

• XX “tiles” in a substation.• Every substation slightly tilted.• Substation closed by EPS wall en top.• Passive cooling by ground connection through poles.

• SKA station formed by multiple substations.• Walkable spaces between substations.• 56m diameter

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Foils

4-11-2010 SKA Station Design 17

Foils put together with conductive glue or paste, or connection based

on capacity coupling

Flat transportation, for assembly folded like an accordeon.

EPS bottom with PCB (transmission line) spaces

Foil groundplane

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FLOWPAD, 2PAD 4M2

Netherlands, United Kingdom

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Next StepsAA-mid

• Other Workpackages: crucial input required

– Open for any LNA. LNA is crucial and we fully support new developments from any group or industry

– Beamformer: We rely on developments at Nancay, fall back is actual EMBRACE LNA (not preferred)

– Selection of front-end antenna principle based on technical input: ORA, Vivaldi?

– Backend, data processing: Shared interface with AA-low, need to match AA-low and AA-mid specs and keep close contacts with Backend developments

– Same for control software

– Same for verification and data reduction software (LOFAR like??)

– Need specific knowledge from candidate sites to define environmental details and use local contacts for radome housing design (temp., wind, animal protection, ..)

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Next StepsAA-mid

• NEXT steps:

– low cost electronical parts

– Detailing electronic subsystems for cost reduction,

– RF line internal connections, new designs and developments

– Tile size definition

– Competion aluminium – foil antenna

– Low-cost tile assembly

– Cooling concept toward design

• Industralisation as in LOFAR (AAVS2)

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Summary

• AAVS - AAmid will make a next step into design to SKA

• concentrating on cost with the technical knowledge of EMBRACE and other instruments and demonstrators

• We are not yet there and need a few years for some significant steps

• Industry is our partner

• Questions?