US SKA TDP Antenna Design Progress US SKA AWG Meeting May 6, 2009, Los Angeles. California Matt Fleming Contributions from Jack Welch Roger Schultz Sandy Weinreb Gerry Harp

US SKA Consortium, Madison, Matt Fleming slide 2 of 27 Summary Reflector Types

US SKA Consortium, Madison, Matt Fleming slide 3 of 27 Type G ( integral surface, composite, CART, MeerKAT ) This configuration may be worth pursuing because it allows nesting the turning head close to the vertex

US SKA Consortium, Madison, Matt Fleming slide 4 of 27 Type F ( integral surface metal, Patriot, Vertex, Etc )

US SKA Consortium, Madison, Matt Fleming slide 5 of 27 Type D & E ( ATA, JPL, Andersen, Others ) This is the area of most interest for large hydroformed shells. We have investigated Lots of backstructures that allow the turning head in close.

US SKA Consortium, Madison, Matt Fleming slide 6 of 27 Rigid Circular Support Beam Study In this study the dish is equipped with a minimal rim beam and supported by a rigid circular beam of various diameters. Stresses are generated by 100 mph side wind from the left. Really type B support

US SKA Consortium, Madison, Matt Fleming slide 7 of 27 Rigid Circular Support Beam Study It seems reasonable to conclude that support at a diameter of less than 65 % will result in over stressed material. Also, it is likely that secondary reflector or feed support legs will need support from near the rim.

US SKA Consortium, Madison, Matt Fleming slide 8 of 27 Rim Beam & Spars Study In this study the dimensions of a rectangular rim beam are varied to maintain acceptable stress while the number of spars is changed. The spars converge at a point 5.0 meters behind the vertex of the dish. The rim beam depth is 2 X it’s width. Stresses are generated by 100 mph side wind from the left while pointed at zenith.

US SKA Consortium, Madison, Matt Fleming slide 9 of 27 Rim Beam & Spars Study It seams reasonable to conclude that only 5 or 6 spars are needed for survival at zenith stow. Also the use of a tripod or quadripod may be a factor in the number of spars chosen.

US SKA Consortium, Madison, Matt Fleming slide 10 of 27 12m dia, 4.5mm thick, bare Al, full sun, no wind. Temperature shown, 70 to 124F, but deflection matches. ( very preliminary )

US SKA Consortium, Madison, Matt Fleming slide 11 of 27 Various backstructures examined. Various important issues discovered. Surface buckling revealed is some cases.

US SKA Consortium, Madison, Matt Fleming slide 12 of 27 Backstructure Spreadsheet Contains the following sort of comparison for all the various designs Reflector weight Backstructure weight Number of members & joints Slenderness ratios Peak stress levels for various loads

US SKA Consortium, Madison, Matt Fleming slide 13 of 27 So, this is our current favorite D It is important to realize this concept will work for symmetric or offset with minimal axis offsets

US SKA Consortium, Madison, Matt Fleming slide 14 of 27 FEA on our current favorite design looks good for survival

Developing Load & Reaction Programs for El bearings & Jack US SKA Consortium, Madison, Matt Fleming slide 15 of 27

US SKA Consortium, Madison, Matt Fleming slide 16 of 27 Antenna Optics and Mount Configurations All other designs will be compared to this design.

US SKA Consortium, Madison, Matt Fleming slide 17 of 27 CostIncrease Reflector0 % Pedestal0 % A-E Offset0 % Total0 % PerformanceLoss Blockage3.1 % Sky10 % Spillover Spacing (min)0 % Symmetric, Cassegrain, Az-El % of ATA Total cost 32 % 7 % 20 %

US SKA Consortium, Madison, Matt Fleming slide 18 of 27 Symmetric, Gregorian, Az-El CostIncrease Reflector0 % Pedestal0 % A-E Offset0 % Total0 % PerformanceLoss Blockage3.1 % Sky10 % Spillover Spacing (min)11 % % of ATA Total cost 32 % 7 % 20 %

US SKA Consortium, Madison, Matt Fleming slide 19 of 27 Symmetric, Prime, Az-El CostIncrease Reflector0 % Pedestal0 % A-E Offset0 % Total0 % PerformanceLoss Blockage2.3 % Sky10 % Spillover Spacing (min)69 % % of ATA Total cost 32 % 7 % 20 %

US SKA Consortium, Madison, Matt Fleming slide 20 of 27 Offset, Gregorian, low, Az-El, CostIncrease Reflector20 % Pedestal26 % A-E Offset20 % Total12.2 % PerformanceLoss Blockage0 % Sky38 % Spillover Spacing (min)42 % % of ATA Total cost 32 % 7 % 20 %

US SKA Consortium, Madison, Matt Fleming slide 21 of 27 Offset, Gregorian, low, Az-El, extended CostIncrease Reflector20 % Pedestal28 % A-E Offset32 % Total14.8 % PerformanceLoss Blockage0 % Sky10 % Spillover Spacing (min)63 % % of ATA Total cost 32 % 7 % 20 %

US SKA Consortium, Madison, Matt Fleming slide 22 of 27 Offset, gregorian, low, Az-El, tilted ped CostIncrease Reflector20 % Pedestal28 % A-E Offset20 % Total12.4 % PerformanceLoss Blockage0 % Sky33 % Spillover Spacing (min)42 % % of ATA Total cost 32 % 7 % 20 %

US SKA Consortium, Madison, Matt Fleming slide 23 of 27 Offset, Gregorian, high, Az-El CostIncrease Reflector20 % Pedestal-6 % A-E Offset-4 % Total5.2 % PerformanceLoss Blockage0 % Sky10 % Spillover Spacing (min)11 % % of ATA Total cost 32 % 7 % 20 %

US SKA Consortium, Madison, Matt Fleming slide 24 of 27 SKA Memo 63 Proposed by Sandy & Roger

US SKA Consortium, Madison, Matt Fleming slide 25 of 27 Extra slide, just for discussion

Clear Aperture US SKA Consortium, Madison, Matt Fleming slide 26 of 27

Support Systems Offset with 0.5m Clearance US SKA Consortium, Madison, Matt Fleming slide 27 of 27

Support Systems Indexer position US SKA Consortium, Madison, Matt Fleming slide 28 of 27

Offset Low US SKA Consortium, Madison, Matt Fleming slide 29 of 27 Stow issues

12° Elevation US SKA Consortium, Madison, Matt Fleming slide 30 of 27

30° Elevation US SKA Consortium, Madison, Matt Fleming slide 31 of 27

45° Elevation US SKA Consortium, Madison, Matt Fleming slide 32 of 27

60° Elevation US SKA Consortium, Madison, Matt Fleming slide 33 of 27

75° Elevation US SKA Consortium, Madison, Matt Fleming slide 34 of 27

90° Elevation US SKA Consortium, Madison, Matt Fleming slide 35 of 27

90° Elevation US SKA Consortium, Madison, Matt Fleming slide 36 of 27

45° Elevation US SKA Consortium, Madison, Matt Fleming slide 37 of 27

ATA Pedestal, Shields US SKA Consortium, Madison, Matt Fleming slide 38 of 27

ATA Pedestal, Unshielded, Temps US SKA Consortium, Madison, Matt Fleming slide 39 of 27

US SKA Consortium, Madison, Matt Fleming slide 40 of 27 ATA Pedestal, Unshielded, Temps

US SKA Consortium, Madison, Matt Fleming slide 41 of 27 ATA Pedestal, Shielded, Temps

US SKA Consortium, Madison, Matt Fleming slide 42 of 27 ATA Pedestal, Shielded, Tilt

US SKA Consortium, Madison, Matt Fleming slide 43 of 27 ATA Temps, various surfaces