Dish Verification Antenna – 1Project
NRC - Herzberg
Gary Hovey
18 November 2013
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SKA Precursor Antennas
Allan Telescope Array MeerKat ASKAP
Dish Verification Antenna 1
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Why Composites
• Superior performance and cost competitive with metal
• Low thermal expansion materials.• Evolving material and manufacturing
technologies• Large membrane surfaces possible.• Can tailor material to cost or performance
requirement.
• Highly accurate precision surface- Stable over gravity, wind, and temperature.
• A stable and predictable radiation pattern- Needed to ensure dynamic range goal of 1 part
in 10 million are met.
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History
• 2005 Began investigation composites reflectors.• 2007 Built two 10m symmetric dishes
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MK 1 Surface Accuracy
Max. Deviations + 4mm - 3mm
RMS 1.2 mm
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Max. Deviations + 2.5mm - 1.7mm
RMS 0.54 mm
MK 2 Surface Accuracy
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Dish Verification Antenna Objectives
Demonstrate performance and manufacturing advantages of composites.
Maintain a cost competitive design that can be mass produced.
Demonstrate mechanical structural innovations yield high performance at competitive cost.
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The main design elements are:
15m Gregorian offset feed-high optics
• Unblocked aperture
• Large space for feeds
• Stiffer, lower cost than feed-low
DVA-1 Antenna Design Description
• Molded single piece rim-supported composite reflectors
• Tubular backup structure
• Tubular composite feedlegs
• Pedestal-type mount allows small offset to elevation axis
• Deep truss backup structure with central pocket for pedestal mount
• Central compliant connector allows movement in wind without distortion
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DVA-1 Mount Components
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DVA-1 Features
Gregorian Shaped Optics - maximize area and minimize noise, (Aeff/Tsys)
Cost effective but robust mount design- Optimized feed support that is stiff, light, and low cost- Simple and stiff back support structure
Rim supported composite reflectors- Carbon fibre low thermal expansion materials, 1/8 of aluminium- Large shaped membrane surfaces possible- Can tailor material to cost or performance requirement- Highly accurate precision surface, stable over gravity, wind, and temperature- A stable and predictable radiation pattern, necessary to ensuring dynamic range
goal of 1 part in 10 million
Secondary focus provides large space for receivers
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DVA-1 Construction
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Pedestal and Reflector on Site
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DVA-1 Status and Future Work
StatusCritical Design Review completed June 2012Construction underway, completion June 2013Testing to begin in 2014- Mechanical verification, static and dynamic- On-sky RF characterization- Feed testbed; EMSS SPF, NRC & CSIRO PAFs, others
Future workInvestigate design and cost/performance improvementsOptimize design for cost and mass productionUpdate mass production study, memo 116
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