US SKA TDP DVA-1 June 28-29, 2012Dish Verification Antenna No. 1 Critical Design Review, Penticton, BC Overview Of DVA-1 Optics Lynn Baker Bill Imbriale German Cortes
US SKA TDP DVA-1 DVA-1 June 28-29, 2012Dish Verification Antenna No. 1 Critical Design Review, Penticton, BC
US SKA TDP DVA-1 DVA-1 Ray Trace Diagram June 28-29, 2012Dish Verification Antenna No. 1 Critical Design Review, Penticton, BC
US SKA TDP DVA-1 June 28-29, 2012Dish Verification Antenna No. 1 Critical Design Review, Penticton, BC Offset Advantage: Electromagnetic Performance 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
US SKA TDP DVA-1 June 28-29, 2012Dish Verification Antenna No. 1 Critical Design Review, Penticton, BC Offset Advantage: Payload Capability Ample space and load capability to mount multiple feeds Feeds, receivers and interchange mechanism out of optical path Access to payload area with out impacting either reflector PAF can be mounted at either secondary or primary focal area For structural cost reasons, DVA-1 is “feed arm high” Easy, effective maintenance access with a standard scissors lift truck
US SKA TDP DVA-1 DVA-1 Beam Pattern, Perfect Feed June 28-29, 2012Dish Verification Antenna No. 1 Critical Design Review, Penticton, BC
US SKA TDP DVA-1 DVA-1 Low Frequency Performance.35 To 2.8 GHz. June 28-29, 2012Dish Verification Antenna No. 1 Critical Design Review, Penticton, BC
US SKA TDP DVA-1 June 28-29, 2012Dish Verification Antenna No. 1 Critical Design Review, Penticton, BC Low System Noise, Now & Future Lowering Tsys is the most cost effective way to increase sensitivity Present LNA’s need cryogenics to minimize noise contribution, expensive Ongoing trend is ever lower noise and future cryogenics should be lower cost. Conclusion: Reduce antenna noise contribution to absolute minimum now. Deep edge tapers improve antenna noise but usually lower efficiency Shaping restores the efficiency and optimizes Aeff / Tsys
US SKA TDP DVA-1 DVA-1 Antenna Temperature June 28-29, 2012Dish Verification Antenna No. 1 Critical Design Review, Penticton, BC
US SKA TDP DVA-1 June 28-29, 2012Dish Verification Antenna No. 1 Critical Design Review, Penticton, BC DVA-1 Modeled Performance With A Corrugated Horn Lynn Baker Bill Imbriale German Cortes
US SKA TDP DVA-1 Corrugated Horn Used In Modeled Performance June 28-29, 2012Dish Verification Antenna No. 1 Critical Design Review, Penticton, BC
US SKA TDP DVA-1 DVA-1 Wide Pattern, Corrugated Horn June 28-29, 2012Dish Verification Antenna No. 1 Critical Design Review, Penticton, BC
US SKA TDP DVA-1 DVA-1 Near Pattern, Corrugated Horn June 28-29, 2012Dish Verification Antenna No. 1 Critical Design Review, Penticton, BC
US SKA TDP DVA-1 DVA-1 Efficiency, 3 Corrugated Horns June 28-29, 2012Dish Verification Antenna No. 1 Critical Design Review, Penticton, BC
US SKA TDP DVA-1 DVA-1 Antenna Temperature, 3 Corrugated Horns June 28-29, 2012Dish Verification Antenna No. 1 Critical Design Review, Penticton, BC
US SKA TDP DVA-1 DVA-1 Aeff/Tsys, 3 Corrugated Horns Assume 15K Receiver June 28-29, 2012Dish Verification Antenna No. 1 Critical Design Review, Penticton, BC
US SKA TDP DVA-1 June 28-29, 2012Dish Verification Antenna No. 1 Critical Design Review, Penticton, BC Far Field Beam Patterns From Modeled Distortions At 10 GHz & 18 GHz. Bill Imbriale
US SKA TDP DVA-1 Beam Pattern at 10 GHz. Undistorted Optics, Ideal Feed June 28-29, 2012Dish Verification Antenna No. 1 Critical Design Review, Penticton, BC
US SKA TDP DVA-1 Beam Pattern at 10 GHz. 25 Celsius Thermal Change (Blue) Undistorted (Red) June 28-29, 2012Dish Verification Antenna No. 1 Critical Design Review, Penticton, BC
US SKA TDP DVA-1 Beam Pattern at 10 GHz. Gravity Deformation at 15 degree Elevation (Blue) Undistorted (Red) June 28-29, 2012Dish Verification Antenna No. 1 Critical Design Review, Penticton, BC
US SKA TDP DVA-1 Beam Pattern at 10 GHz. Gravity Deformation at 55 degree Elevation (Blue) Undistorted (Red) June 28-29, 2012Dish Verification Antenna No. 1 Critical Design Review, Penticton, BC
US SKA TDP DVA-1 Beam Pattern at 10 GHz. Gravity Deformation at 90 degree Elevation (Blue) Undistorted (Red) June 28-29, 2012Dish Verification Antenna No. 1 Critical Design Review, Penticton, BC
US SKA TDP DVA-1 Beam Pattern at 10 GHz. 25 kph Wind at 15 degree Elevation (Blue) Undistorted (Red) June 28-29, 2012Dish Verification Antenna No. 1 Critical Design Review, Penticton, BC
US SKA TDP DVA-1 Beam Pattern at 10 GHz. 25 kph Wind at 55 degree Elevation (Blue) Undistorted (Red) June 28-29, 2012Dish Verification Antenna No. 1 Critical Design Review, Penticton, BC
US SKA TDP DVA-1 Beam Pattern at 10 GHz. 25 kph Wind at 90 degree Elevation (Blue) Undistorted (Red) June 28-29, 2012Dish Verification Antenna No. 1 Critical Design Review, Penticton, BC
US SKA TDP DVA-1 Beam Pattern at 18 GHz. Gravity Deformation at 55 degree Elevation (Blue) Undistorted (Red) June 28-29, 2012Dish Verification Antenna No. 1 Critical Design Review, Penticton, BC
US SKA TDP DVA-1 Beam Pattern at 18 GHz. Gravity Deformation at 15 degree Elevation (Blue) Undistorted (Red) June 28-29, 2012Dish Verification Antenna No. 1 Critical Design Review, Penticton, BC
US SKA TDP DVA-1 June 28-29, 2012Dish Verification Antenna No. 1 Critical Design Review, Penticton, BC Freq Peak Scan Scan On-axis Peak Peak Beam Width Case Gain Offset Orthogonal Gain Sidelobe X-pol X Y (GHz) (dB) mdeg mdeg (dB) (dB) (dB) (deg) (deg) Undistorted Thermal Gravity 15 degrees Gravity 55 degrees Gravity 90 degrees Wind 15 degrees Wind 55 degrees Wind 90 degrees Calculated Performance Of Each Distortion Case
US SKA TDP DVA-1 June 28-29, 2012Dish Verification Antenna No. 1 Critical Design Review, Penticton, BC Conclusions Shaped, offset gregorian reflectors yield very high performance Cost increment for offset design is modest Very low noise performance maximizes Aeff/Tsys Mechanical design with single piece reflectors is very stiff Equivalent RMS error from all sources is.45 mm., worst case
US SKA TDP DVA-1 June 28-29, 2012Dish Verification Antenna No. 1 Critical Design Review, Penticton, BC End