DVA1 Project Gary Hovey and Gordon Lacy Herzberg Jamboree 23 October 2014 NRC-Herzberg Astronomy Technology Program - Penticton

Outline DVA1 Overview: Challenges, Motivation Key innovations Results Development of DVA1 for the SKA2 of 28

SKA Dishes over 50 times more sensitive and capable than existing cm wave radio-telescopes m offset Gregorian dishes 350 MHz – 24 GHz Development of DVA1 for the SKA3 of 28

Other Designs Australian SKA Pathfinder Development of DVA1 for the SKA4 of 28 Allen Telescope Array South African MeerKat

Evolution of Improved Cost/Performance Development of DVA1 for the SKA5 of 28 Improving Materials, Design, and Manufacturing Cost/performance

DVA-1: Design Approach and Goals SKA Challenge: A leap in sensitivity and dynamic range requires a corresponding leap in antenna cost/performance. 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 Development of DVA1 for the SKA6 of 28

DVA1: Design Approach and Goals (cont.) 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 Development of DVA1 for the SKA7 of 28

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 beam pattern distortion 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 CTE matched carbon tubes for high thermal stability. 8 of 28Development of DVA1 for the SKA

DVA1: Mechanical 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 9 of 28Development of DVA1 for the SKA

Background and Project Status Began investigating composites in 2005 Built two 10m prime focus antennas in Started collaboration with US-TDP in 2009 −Design phase lead by US-TDP −Construction phase lead by NRC 15m Gregorian Offset selected after much investigation DVA1 CoDR in early 2011 DVA1 PDR in late 2011 CDR in mid 2012 Fabrication reflector and pedestal mid-2013 First light expected in late summer. Testing: Mechanical, Ku band holography and L-band summer through fall. Development of DVA1 for the SKA10 of 28

DVA1 Predicted Temperature Stability Development of DVA1 for the SKA11 of 28 Beam Pattern at 10 GHz. 25 Celsius Thermal Change (Blue) Undistorted (Red)

Beam Pattern at 18GHz 15  Elevation Development of DVA1 for the SKA12 of 28 Undistorted (Red). 15 degree Elevation (Blue) Effect mainly a pointing correction as 25kph wind has a negligible effect on pattern

DVA1 Primary Reflector Damage and Repairs Collapsed SurfaceAfter being popped out with air bags

DVA1 Repair Activities

DVA-1 Reflector Repairs

DVA-1 Reflector Accuracy After Repairs Post repair error = 0.89 mm rms Weighted error = 0.70 mm rms Mold error =.48 rms

Improved Results: GDSatcom Secondary Reflector We have now built two sub reflectors for GDSatcom (Antenna contractor for MeerKat) RMS of reflector 0.1mm Mold RMS 0.058mm

First Light Spectra to GHz Nimiq 6 Ku band Satellite 12.2 to 12.7 GHz DVA1 - Performance and Status18 of 34

Measured Surface Error Laser Tracker vs Holography

Azimuth and Elevation Beam Cuts at 12.2 GHz

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 Development of DVA1 for the SKA21 of 28

RF Testing Ku band holography Aperture/surface errors Antenna pattern Pointing behaviour Stability Repeatability Performance over load cases, gravity, wind and temperature Sensitivity Tipping curves Aperture efficiency Ku Band Horn MeerKat L-band receiver DVA1 - Performance and Status22 of 34

23Development of DVA1 for the SKA23 Gary Hovey, Project Manager Gordon Lacy, Project Engineer

Development of DVA1 for the SKA24 of 28