Phased Array Feed Development
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Atacama Large Millimeter/submillimeter Array Expanded Very Large Array Robert C. Byrd Green Bank Telescope Very Long Baseline Array Phased Array Feed Development FAST Visitors, July 23, 2010 – Charlottesville, Va Rick Fisher
description
Phased Array Feed Development. FAST Visitors, July 23, 2010 – Charlottesville, Va. Rick Fisher. Phased Array Feed Project. Collaboration with Brigham Young University First PAF demo 1997 on 43-m telescope Objective: Maximize A 2 eff Ω /T 2 sys Key technical challenges - PowerPoint PPT Presentation
Transcript of Phased Array Feed Development
Atacama Large Millimeter/submillimeter ArrayExpanded Very Large Array
Robert C. Byrd Green Bank TelescopeVery Long Baseline Array
Phased Array Feed DevelopmentFAST Visitors, July 23, 2010 – Charlottesville, Va
Rick Fisher
Phased Array Feed Project• Collaboration with Brigham Young University• First PAF demo 1997 on 43-m telescope• Objective: Maximize A2
effΩ/T2sys
• Key technical challenges– Compensation for mutual coupling between array
elements– Noise reduction with cryogenics
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Beamforming
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LNAsFPA Receiver Chains
Reflector Digital Beamforming
Formed Beam Patterns
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Cross Elevation (Degrees)
Ele
vatio
n (D
egre
es)
-1 0 1
-1
0
1
0
0.2
0.4
0.6
0.8
1
Cross Elevation (Degrees)
Ele
vatio
n (D
egre
es)
-1 0 1
-1
0
1
0
0.2
0.4
0.6
0.8
1
Cross Elevation (Degrees)
Ele
vatio
n (D
egre
es)
-1 0 1
-1
0
1
0
0.2
0.4
0.6
0.8
1
Cross Elevation (Degrees)
Elev
atio
n (D
egre
es)
-1 0 1
-1
0
1
0
0.2
0.4
0.6
0.8
1
Source: Cas A, 1612 MHz0.1 degree pointing grid
Cygnus X Region Mosaic
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Cross Elevation (Degrees)
Ele
vatio
n (D
egre
es)
-4 -2 0 2 4-4
-2
0
2
4
0
50
100
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Canadian Galactic Plane SurveyConvolved to 20-m Beam
Noise Budget (Uncooled Array)
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Measured Model
LNA Tmin 33 K 33 K
Noise coupling 20 K 23 K
Spillover 5 K 5 K
Sky 3 K 3 K
Loss 4 K --
Tsys: 65 K 64 K
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Next Steps
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Dewar Close-up
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1020 RefrigeratorLNA – Antenna Element Interface
Cryogenic Amplifier Interface
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Interface to Antenna Element(@300K, at least initially)
Dual Channel LNA(@15K)
Development System Evolution
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Final Configuration
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First Science PAF Instrument
• 7-Beam, 19-Element Array on GBT• Tsys < 25 K, Aperture Efficiency > 0.7• 450-MHz R.F. Bandwidth• 300 MHz Beamformer with Pulsar Search
Capability
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• http://science.nrao.edu/paf
