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SKA TDP Antenna Optics

SKA-TDP AWG Antenna Workshop San Francisco, March 13-14, 2008. SKA TDP Antenna Optics. By Germán Cortés M. Cornell University Ithaca NY 14853, USA. National Astronomy and Ionosphere Center. Overview. Introduction SKA TDP Dishes + WBSPF Optics Design Plan

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SKA TDP Antenna Optics

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  1. SKA-TDP AWG Antenna Workshop San Francisco, March 13-14, 2008 SKA TDP Antenna Optics By Germán Cortés M. Cornell University Ithaca NY 14853, USA National Astronomy and Ionosphere Center

  2. Overview • Introduction • SKA TDP Dishes + WBSPF Optics Design Plan • SKA TDP Antenna Work Breakdown • SKA TDP Baseline Antenna Optics. • Summary

  3. Current SKA TDP Antenna

  4. Current SKA TDP Antenna

  5. SKA TDP Dishes + WBSPF Optics Design Plan

  6. SKA TDP Reflector + WBSP Feed Optics Design Plan • Detailed WBSP Feed characterization • Co-Pol and Cross-Pol Radiation Patterns • Gain • Input Matching • Losses • Phase Center Variations

  7. WBSP Feed Far Field Radiation Pattern 10 GHz Co-Pol Dir = 10.11 dBi X-Pol -1.08 dBi

  8. SKA TDP Reflector + WBSP Feed Optics Design Plan • Detailed WBSP Feed characterization • Co-Pol and Cross-Pol Radiation Patterns • Gain • Input Matching • Losses • Phase Center Variations • Matching Optics Parameters

  9. The SKA TDP Reflectors Possible Configurations Gregorian is Preferred Symmetric Reflector Off-Axis Reflector

  10. SKA TDP Reflector + WBSP Feed Optics Design Plan • Antenna Analysis and Design Optimization • Co-Pol and Cross-Pol Radiation Patterns • Aperture Efficiency • Antenna Temperature vs. elev & freq • Aeff/Tsys Optimization • Matching Optics for Different Configurations • Prime Focus • Secondary Focus Solutions • Multiple Focus Solutions

  11. 8m Reflector+Baseline FeedFar Field Radiation Pattern at 700 MHz Symmetric Reflector Co-Pol Symmetric Reflector X-Pol

  12. 6m Offset Reflector+Baseline FeedFar Field Radiation Pattern at 500 MHz Off-Axis Reflector Co-Pol Off-Axis Reflector X-Pol

  13. SKA TDP Reflector + WBSP Feed Optics Design Plan • Antenna Analysis and Design Optimization • Co-Pol and Cross-Pol Radiation Patterns • Aperture Efficiency • Antenna Temperature vs. elev & freq • Aeff/Tsys Optimization • Dynamic Range Issues: Far Side Lobe Levels • Matching Optics for Different Configurations • Prime Focus • Secondary Focus Solutions • Multiple Focus Solutions

  14. SKA Offset Design Prime Focus: Wide Pattern Wide Band FeedFreq= 1.400 GHz, f=5.2m -42.9 dB -42.9 dB -39.1 dB -33.9 dB -14.2 dB -40.8 dB Co-Polar Wide Pattern X-Polar Wide Pattern

  15. Far Field Radiation Patterns including Quadrupod Strut Diffraction Effects -126 dB -46 dB -152 dB -46 dB =178° =82° =180° =82° -85 dB -123 dB -45 dB -73 dB =106° =106° =14° =14° Wide Pattern 1.3 GHz Wide Pattern 32 GHz

  16. SKA TDP Reflector + WBSP Feed Optics Design Plan • Antenna Analysis and Design Optimization • Co-Pol and Cross-Pol Radiation Patterns • Aperture Efficiency • Antenna Temperature vs. elev & freq • Aeff/Tsys Optimization • Dynamic Range Issues: Far Side Lobe Levels • Matching Optics for Different Configurations • Prime Focus • Secondary Focus Solutions • Multiple Focus Solutions

  17. The SKA TDP Reflectors Possible Configurations Gregorian Off-Axis

  18. SKA TDP Reflector + WBSP Feed Optics Design Plan • But,… In order to do this we need to agree in some initial parameters….

  19. SKA TDP Antenna Work Breakdown

  20. SKA TDP Antenna Work Breakdown Science Data Transport Monitoring & Control UWB Feeds Power Optics Reflector Mount Pedestal Foundation

  21. SKA TDP Antenna Work Breakdown UWB Feeds Science Data Transport Optics Monitoring & Control Power Reflector Mount Pedestal Foundation

  22. SKA TDP Antenna Work Breakdown UWB Feeds Optics Reflector Mount Monitoring & Control Power Science Data Transport Pedestal Foundation

  23. SKA TDP Antenna Work Breakdown UWB Feeds Optics

  24. SKA TDP Antenna OpticsSpecification UWB Feeds Optics Aeff/Tsys Frequency Diameter

  25. SKA Dishes+WBSPF Technology Paths Frequency 0.07 0.2 0.5 0.8 1.5 10 GHz 1 AA’s Dishes Ø15m + WBSPF 2 AA’s PHASE II 3b 1.5 GHz 10 GHz PAF’s 3c 3a Preliminary Specifications for the Square Kilometer Array v2.7.1 Dec. 4 2007

  26. SKA Dishes+WBSPF Technology Paths Frequency 0.07 0.2 0.5 0.8 1.5 10 GHz 1 AA’s Dishes Ø15m + WBSPF 2 AA’s PHASE II 3b 1.5 GHz 10 GHz PAF’s 3c AA’s 0.8 GHz 10 GHz 3a Preliminary Specifications for the Square Kilometer Array v2.7.1 Dec. 4 2007

  27. SKA Dishes+WBSPF Technology Paths Frequency 0.07 0.2 0.5 0.8 1.5 10 GHz 1 AA’s Dishes Ø15m + WBSPF 2 AA’s PHASE II 3b 1.5 GHz 10 GHz PAF’s 3c AA’s 0.8 GHz 10 GHz 3a 0.5 GHz 10 GHz Preliminary Specifications for the Square Kilometer Array v2.7.1 Dec. 4 2007

  28. SKA Dishes+WBSPF Technology Paths Frequency 0.07 0.2 0.5 0.8 1.5 10 GHz 1 AA’s Dishes Ø15m + WBSPF 2 A Tsys NII AA’s 2000 PHASE II 3b 1.5 GHz 10 GHz 70% 30K PAF’s 2400 3c AA’s 0.8 GHz 10 GHz 70% 30K 3000 3a 0.5 GHz 10 GHz 70% 30K Preliminary Specifications for the Square Kilometer Array v2.7.1 Dec. 4 2007

  29. SKA TDP Antenna OpticsAeff/Tsys Point Source Sensitivity 0.2 0.5 0.7 1.5 3.0 10.0 Aeff/Tsys [m2/K] Preliminary Specifications for the Square Kilometer Array v2.7.1 Dec. 4 2007

  30. SKA TDP Antenna OpticsAeff/Tsys Point Source Sensitivity 0.2 0.5 0.7 1.5 3.0 10.0 Aeff/Tsys [m2/K] SKA TDP

  31. SKA TDP Antenna OpticsTsys for a 15m Ø Dish, A =70% 0.2 0.5 0.7 1.5 3.0 10.0 SKA TDP

  32. SKA TDP Antenna OpticsTsys for a 15m Ø Dish, A =70% 0.2 0.5 0.7 1.5 3.0 10.0

  33. SKA TDP Antenna OpticsSpecification Frequency 0.07 0.2 0.5 0.8 1.5 10 GHz UWB Feeds 0.5 GHz 10 GHz Optics Aeff/Tsys  Frequency  Diameter

  34. SKA TDP Antenna OpticsSpecification Frequency UWB Feeds 0.07 0.2 0.5 0.8 1.5 10 GHz 0.5 GHz 10 GHz Optics Aeff/Tsys  Frequency  Diameter

  35. SKA TDP Antenna OpticsSpecification Frequency UWB Feeds  0.07 0.2 0.5 0.8 1.5 10 GHz 0.5 GHz 10 GHz Optics Room Temp 0.3 3 GHz Cooled 1.0 GHz 10 GHz Aeff/Tsys  Frequency  Diameter

  36. SKA TDP Antenna OpticsSpecification Frequency UWB Feeds  0.07 0.2 0.5 0.8 1.5 10 GHz 0.5 GHz 10 GHz Optics Room Temp 0.3 3 GHz Cooled 1.0 GHz 10 GHz Aeff/Tsys  6 8 10 12 14 16 Ø [m] Frequency  10 m  16 m Diameter

  37. SKA TDP Antenna OpticsSpecification Frequency UWB Feeds  0.07 0.2 0.5 0.8 1.5 10 GHz 0.5 GHz 10 GHz Optics Room Temp 0.3 3 GHz Cooled 1.0 GHz 10 GHz Aeff/Tsys  6 8 10 12 14 16 Ø [m] Frequency  10 m  16 m Diameter Survey Speed Point Source Sensitivity

  38. Prime Focus Aeff/Tsys vs. Frequencyfor Na=4500 Reflector 12m Reflector 8m Reflector 6m

  39. SKA TDP Baseline Antenna Optics for Dishes + WBSPF

  40. SKA TDP Reflector + WBSP Feed Baseline Optics Design Plan • Baseline Optics Designs that uses WBSPF • Diameter: 12 m to 16 m • Frequency: < 0.5 GHz to 10 GHz • 1st Step: Optimized Aeff/Tsys Optics Design for a Symmetric Configuration: • Prime Focus WBSPF: 0.3 GHz to 3 GHz • Secondary Focus WBSPF: 1 to 10 GHz • 2st Step: Optimized Aeff/Tsys Optics Design for a Off-axis Configuration

  41. SKA TDP Reflector + WBSP Feed Optimized Prime Focus • Diameter: 16 m • WBSPF 0.3 to 3 GHz • f1/D Optimized for for Aeff/Tsys 12 m 16 m

  42. SKA Symmetric AntennaAeff/Tsys Prime focus Optimization using UWB Feed (TA@45°, Trx=10K, Freq: 0.5 GHz to 2.5 GHz) 53°

  43. SKA Symmetric AntennaAeff/Tsys Prime focus Optimization using UWB Feed (TA@45°, Trx=10K, Freq: 0.5 GHz to 2.5 GHz) 79° 64° 53°

  44. SKA TDP Reflector + WBSP Feed Optimized Prime Focus • Diameter: 16 m • WBSPF 0.3 to 3 GHz • Optimized for for Aeff/Tsys: f1/D ~ 0.38 12 m 16 m

  45. SKA TDP Reflector + WBSP Feed Optimized Secondary Focus • Diameter: 12 m • WBSPF 1 to 10 GHz • Optimized for for Aeff/Tsys: f2/D > f1/D 12 m

  46. SKA TDP Reflector + WBSP Feed Optimized Secondary Focus • Diameter: 12 m • WBSPF 1 to 10 GHz • Optimized for for Aeff/Tsys: f2/D > f1/D • Shaped Optics is also an option for this frequency band. 12 m

  47. SKA TDP Reflector + WBSP Feed Optimized Multiple Focus • Prime Focus Ø16 m • WBSPF 0.3 to 3 GHz • Optimized for for Aeff/Tsys: f1/D ~ 0.38 • Secondary Focus Ø12 m • WBSPF 1 to 10 GHz • Optimized for for Aeff/Tsys: f2/D > f1/D 12 m 16 m

  48. SKA Technology Path TDP WBSP Feeds Wide Band Feeds Bandwidth 10dB TN Input Match 5:1 10:1 20:1 62° Chalmers ~10:1 -7 dB 4 - 12 GHz 66° 30K Quad-Ridge ~8:1 -6 dB 65° Sinuous/Gnd ~10:1 -8 dB 65° QSC Feed -10 dB ~15:1 1 - 7 GHz 43° 45K ATA >20:1 -14 dB

  49. Summary • We are proposing a Frequency coverage for the SKA TDP that goes from < 0.5 to 10 GHz, and that uses WBSPF + Dishes. • TDP is going to provide two WBSP feeds that demonstrate the performance of these feeds: • One at room temperature from 0.3 to 3 GHz. • One Cooled feed from 1 to 10 GHz.

  50. Summary Cont… • We proposed a dish diameter between 12m to 16 m. And still have to agree in a dish diameter for the electromagnetic analysis. • We are going to provide an antenna analysis and optimization for baseline symmetric and off-axis prime focus configurations that uses WBSP feeds. • We are going to analyzed options for secondary or multiple focal point configurations. • We are going to assess the issue of the far SLL for Dynamic Range.

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