Embed Size (px)
Citation preview
DVA-1 Project Overview
Gordon Lacy
April 2014
The Dish Verification Antenna, DVA-1
• 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.
• 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
DVA-1: Shaped Offset Optics Advantage
DVA-1
6
DVA-1: Composites for Performance
Structural Test Composite Design Consideration
Metallic Design Consideration
Creep high static load high static load
Static Strength Material properties Material properties
Fatigue Life High cyclic load High cyclic load
Glass Transition Temp. Choose resin with sufficiently high value.
NA
Impact Resistance Engineering requirement 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) Paint and Primer
Fungus growth Paint Paint
Recovery from Disaster
Crack Repair
DVA-1 Reflector Repairs
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
DVA-1 Secondary Reflector Accuracy
•Secondary Part RMS without antenna weighting 0.2mm
•With antenna weighting 0.11mm
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 Q4 2012.
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
Questions?
