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