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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
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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 A2effΩ/T2sys • Key technical challenges • Compensation for mutual coupling between array elements • Noise reduction with cryogenics
Beamforming Receiver Chains Digital Beamforming Reflector FPA LNAs
Formed Beam Patterns Source: Cas A, 1612 MHz 0.1 degree pointing grid
Cygnus X Region Mosaic Canadian Galactic Plane Survey Convolved to 20-m Beam
Noise Budget (Uncooled Array) MeasuredModel LNA Tmin33 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 ---------- ----------
Dewar Close-up 1020 Refrigerator LNA – Antenna Element Interface
Cryogenic Amplifier Interface Dual Channel LNA (@15K) Interface to Antenna Element (@300K, at least initially)
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 • http://science.nrao.edu/paf