DVA1 Project Status Gary Hovey and Gordon Lacy ngVLA Workshop, April NRC-Herzberg Astronomy Technology Program - Penticton

Background Began investigating composites in 2005 Built two reflectors in 2007 Started collaboration with US-TDP in 2009 −Design phase lead by US-TDP −Construction phase lead by NRC CoDR in early 2011 PDR in late 2011 CDR in mid 2012 Fabrication reflector and pedestal mid-2013 Final assembly and test through to fall 2014 DVA1 - Performance and Status2 of 34

DVA-1: Design for Cost Lower cost through −Simplicity of design −Minimal part count −Modular design −Low labour content −Minimal use of custom sizes and part −Use of advanced materials −Use of scalable mass fabrication processes −Optimal optics over the prime frequency range 1-10GHz. −Feed-up design DVA1 - Performance and Status3 of 25

DVA1: Design For Performance Improved optics and stability performance through Use of advanced materials Shaped optics to maximise A eff / T sys Improved stability over all load conditions −Feed-high design lowering peak cross section to wind −Compact turning-head and mount to minimise moments −Single piece rim supported reflector immunity to translational loads distortions uniform and low order −High stiffness and low CTE using carbon fibre composites −Composite reflector with embedded metal mesh Reflectivity of Aluminium with the stiffness of carbon. Low moving mass -> superior closed loop response Design for low maintenance upkeep and burden, as well as long life and durability DVA1 - Performance and Status4 of 25

DVA1: Design Features The main design elements are: 15m Gregorian offset feed-high optics Unblocked aperture Large space for feeds Stiffer, lower cost than feed-low 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 DVA1 - Performance and Status5 of 25 Superior Performance Thermal Wind Gravity

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. DVA1 - Performance and Status6 of 25

DVA1: Estimated Sensitivity DVA-1 Aeff/Tsys using Corrugated Horns Assumes 15K Receiver DVA1 - Performance and Status7 of 25

DVA1: Estimated Performance in Wind Beam Pattern at 10 GHz. 25 kph Wind at 15 degree Elevation (Blue) Undistorted (Red) DVA1 - Performance and Status8 of 25

DVA1 Predicted Temperature Stability Beam Pattern at 10 GHz. 25 Celsius Thermal Change (Blue) Undistorted (Red) DVA1 - Performance and Status9 of 25

Beam Pattern at 18GHz 15  Elevation Undistorted (Red). 15 degree Elevation (Blue) Effect mainly a pointing correction as 25kph wind has a negligible effect on pattern DVA1 - Performance and Status10 of 25

September 2014

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

Primary Dish Surface Scan, Rim Horizontal (Bird Bath). Primary reflector surface deviations. RMS error, uncorrected for aperture weighting 0.89mm, otherwise.7mm rms Most of surface is within ±1.0mm (green) Most red areas are repaired areas, a result of the helicopter incident Almost all other features are in the mold surface (horizontal banding, grid feature in upper right quadrant). DVA1 - Performance and Status13 of 25

Laser Tracker vs Holography of Primary DVA1 - Performance and Status14 of 25

Reflector Temperature Stability Primary Reflector Coupon Testing 5.62 μm/m o C DRAO test August 6th 5.42 ± 1.08 μm/m o C Secondary Reflector (estimated) 3.18 μm/m o C < CTE secondary < 5.62 μm/m o C Aluminium > 4 times higher 23.6 μm/m o C DVA1 - Performance and Status15 of 25

Surface Stability (no correlations with wind or temperature) DVA1 - Performance and Status16 of 25

Average Surface Error of 18 Holography Maps (28 Hrs) RMS.85mm DVA1 - Performance and Status17 of 25 Deviations from average.08mm RMS

MeerKat Receiver Noise Temperature Testing DVA1 - Performance and Status18 of 25

EMSS L-Band Receiver for MeerKat DVA1 - Performance and Status19 of 25

Azimuth Pattern at MHz (GOES West Satellite) DVA1 - Performance and Status20 of 25

Elevation Pattern at MHz (GOES West Satellite) DVA1 - Performance and Status21 of 25

Preliminary Tipping Curves Results DVA1 - Performance and Status22 of  18.5  Results Preliminary and likely low by as much as 1.5  K 58.5 

Aperture Efficiency with MeerKat and New (LB) Horn DVA1 - Performance and Status23 of 25

Aeff/Tsys with MeerKat and New (LB) Horn DVA1 - Performance and Status24 of 25

Cost ItemMaterialsLabourSub-contractTotals Reflectors, feed platform and support structures Composite Dish Surface, Secondary, Central Reinforcement$111,000$63,400 Composite Backing Pieces, fabrication portion, not including molds$23,250 Dish Rim Connector, labour (material in line 3)$14,000 Ball studs$6,132 PDSS$84,874 Feed Platform$6,700 Secondary Support Structure $85,000 Sub Totals$111,000$77,400$205,956$394,356 Pedestal Components Tower, contract with Minex Engineering$300,000 Tower, misc extra parts, package 1$19,920 Tower, misc extra parts, package 2$90,600 Tower, additional items$14,836 Drive system (motors, control system and encoders)$43,000 Painting$5,000 Sub Totals $473,356 Grand Total$867,712 DVA1 - Performance and Status25 of 25

Issues and Technical Risks Key retired technical (technology) risks Composite reflectors meet requirements for −Reflectivity −Mechanical and thermal properties −Surface accuracy Outstanding risks now very low. −Majority have been mitigated by simulation/measurement −Those remaining will be retired by RF testing DVA1 - Performance and Status26 of 25

27 Questions? Gary Hovey, Project Manager Gordon Lacy, Project Engineer DVA1 - Performance and Status27 of 25