1. DVA-1 Project Overview
Gordon Lacy
April 2014

2. The Dish Verification Antenna, DVA-1
Built on composite knowledge from 2 previous 10m composite dishes
Combined composite expertise with US TDP group (ATA design)
Key Features:
A 15m aperture, feed-high offset Gregorian with shaped optics
Rim supported composite shell primary and secondary
Composite tubes supporting feed platform and secondary
Deep tubular truss backing structure

3. DVA-1: Designed for High Dynamic Range Capability
High Thermal Performance
Rim supported monocoque design along with very low CTE materials keeps all thermal movement both small and very uniform to minimize effect on beam pattern
High Performance in Wind and Gravity
Central compliant connector allows some structural sag without inducing unwanted distortion at center of dish
Rim supported design keeps dish deflections to absolute minimum and concentrates any deflections at rim where effect on performance is small.
Extremely deep truss back structure keeps dish shape as close to rigid as is possible.
High Overall Optics Stability
Secondary and feed platform support optimized to maximize stiffness using shape optimization software.
Secondary and feed support tubes use zero and matched CTE carbon tubes for extremely high thermal stability.

4. DVA-1: Shaped Offset Optics Advantage
Clear optical path, no blockage or scattering
Combined with shaped optics, leads to very low spillover (~ -50db wide angle)
Very low spillover yields very low antenna noise temperature (<6 K ground)
Very low spillover results in high rejection of RFI and strong sources
Shaped optics yield high efficiencies, total result is a high Aeff / Tsys

5. DVA-1

6. DVA-1: Composites for Performance
Structural Test
Composite Design Consideration
Metallic Design Consideration
Creep
high static load
Static Strength
Material properties
Fatigue Life
High cyclic load
Glass Transition Temp.
Choose resin with sufficiently high value. NA
Impact Resistance
Engineering requirement
Galvanic Corrosion
Encapsulate reflective layer
Paint and primer
UV, Moisture, Humidity
Paint (no primer required) and resin properties
Paint and Primer
Reflectivity Degradation
Paint (no primer required)
Fungus growth
Paint

7. Recovery from Disaster

8. Crack Repair

9. DVA-1 Reflector Repairs

10. DVA-1 Reflector Accuracy After Repairs
Primary reflector RMS after repairs and without antenna weighting, 1.0mm
RMS with repair areas removed, 0.7mm without antenna weighting

11. DVA-1 Secondary Reflector Accuracy
Secondary Part RMS without antenna weighting 0.2mm
With antenna weighting 0.11mm

12. GDSatcom Secondary Reflector
We have now built two sub reflectors for the GDSatcom Meerkat project
RMS of reflector 0.090mm
Mold RMS 0.058mm

13. DVA-1 Prototype Target:
To meet all of the SKA performance goals, as of Q
2014 Target
To meet the SKA 2012 performance goals
To investigate the SKA 2014 low frequency requirements
To investigate the SKA 2014 high frequency requirements

14. Questions?

15. End Gordon Lacy, P.Eng. Tel: 250-497-2340 Gordon.lacy@nrc-cnrc.gc.ca 15