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EVLA FEEDS DESIGN

EVLA FEEDS DESIGN. S. Srikanth NRAO/Charlottesville. VLA Cassegrain Geometry Drawing. Current Receiver Bands. VLA Vertex Feed Cone. EVLA Receiver Bands. Selection of Bands. Minimize number of receivers Use existing technology

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EVLA FEEDS DESIGN

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  1. EVLA FEEDS DESIGN S. Srikanth NRAO/Charlottesville EVLA Feed/FE PDR February 12-13, 2002

  2. VLA Cassegrain Geometry Drawing

  3. Current Receiver Bands EVLA Feed/FE PDR February 12-13, 2002

  4. VLA Vertex Feed Cone EVLA Feed/FE PDR February 12-13, 2002

  5. EVLA Receiver Bands EVLA Feed/FE PDR February 12-13, 2002

  6. Selection of Bands • Minimize number of receivers • Use existing technology • Performance at the band edges - feeds, polarizers, amplifiers etc. EVLA Feed/FE PDR February 12-13, 2002

  7. Selection of Feed Type and Parameters • Nominal taper of -13 dB at 9.25 degrees • Compact horns where space is limited • Ring-loaded slots (except for Q-band) • Number of corrugations/wavelength - 3.8 EVLA Feed/FE PDR February 12-13, 2002

  8. Conventional Corrugations EVLA Feed/FE PDR February 12-13, 2002

  9. Ring-Loaded Corrugations EVLA Feed/FE PDR February 12-13, 2002

  10. VSWR – Conventional and Ring-Loaded EVLA Feed/FE PDR February 12-13, 2002

  11. EVLA Feed/FE PDR February 12-13, 2002

  12. EVLA Feed/FE PDR February 12-13, 2002

  13. EVLA Feed/FE PDR February 12-13, 2002

  14. EVLA Feed/FE PDR February 12-13, 2002

  15. EVLA Feed/FE PDR February 12-13, 2002

  16. EVLA Feed/FE PDR February 12-13, 2002

  17. Linear Taper Horn 75" OD – 1.0 GHz EVLA Feed/FE PDR February 12-13, 2002

  18. Linear Taper Horn 75" OD – 1.4 GHz EVLA Feed/FE PDR February 12-13, 2002

  19. EVLA Feed/FE PDR February 12-13, 2002

  20. Comparison of 75" OD and 62" OD Feeds EVLA Feed/FE PDR February 12-13, 2002

  21. Compact Horn – 75" OD 1.0 GHz EVLA Feed/FE PDR February 12-13, 2002

  22. Compact Horn – 62" OD 1.0 GHz EVLA Feed/FE PDR February 12-13, 2002

  23. Compact Horn – 75" OD 1.4 GHz EVLA Feed/FE PDR February 12-13, 2002

  24. Compact Horn – 62" OD 1.4 GHz EVLA Feed/FE PDR February 12-13, 2002

  25. VLA Cassegrain Geometry Drawing

  26. ANALYSIS METHODOLOGY EVLA Feed/FE PDR February 12-13, 2002

  27. ANALYSIS METHODOLOGY 6. Grids on the reflector surface  = /max  = /sinmax EVLA Feed/FE PDR February 12-13, 2002

  28. Comparison of Subreflector Patternsat 1.5 GHz ( = 0°) JPL Software NRAO Software EVLA Feed/FE PDR February 12-13, 2002

  29. Comparison of Subreflector Patternsat 1.5 GHz ( = 90°) JPL Software NRAO Software EVLA Feed/FE PDR February 12-13, 2002

  30. Comparison of Main Reflector Patternsat 1.465 GHz NRAO Software -4 -2 0 2 4 Measured EVLA Feed/FE PDR February 12-13, 2002

  31. Subreflector Scatter Pattern – 1.4 GHzCompact Horn - 75" ODSymmetric Plane EVLA Feed/FE PDR February 12-13, 2002

  32. Subreflector Scatter Pattern – 1.4 GHzCompact Horn - 62" ODSymmetric Plane EVLA Feed/FE PDR February 12-13, 2002

  33. Subreflector Scatter Pattern – 1.4 GHzCompact Horn - 75" ODAsymmetric Plane EVLA Feed/FE PDR February 12-13, 2002

  34. Subreflector Scatter Pattern – 1.4 GHzCompact Horn - 62" ODAsymmetric Plane EVLA Feed/FE PDR February 12-13, 2002

  35. Subreflector Scatter Pattern – 1.4 GHzCompact Horn - 62" ODSymmetric Plane EVLA Feed/FE PDR February 12-13, 2002

  36. Subreflector Scatter Pattern – 1.4 GHzCompact Horn - 62" ODAsymmetric Plane EVLA Feed/FE PDR February 12-13, 2002

  37. Main Reflector Pattern – 1.4 GHzCompact Horn - 75" OD EVLA Feed/FE PDR February 12-13, 2002

  38. Main Reflector Pattern – 1.4 GHzCompact Horn - 62" OD EVLA Feed/FE PDR February 12-13, 2002

  39. Comparison of 75" OD and 62" OD Feeds EVLA Feed/FE PDR February 12-13, 2002

  40. Compact Horn –75" OD EVLA Feed/FE PDR February 12-13, 2002

  41. Compact Horn – 62" OD EVLA Feed/FE PDR February 12-13, 2002

  42. Comparison of 75" OD and 62" OD Feeds EVLA Feed/FE PDR February 12-13, 2002

  43. Comparison of 75" OD and 62" OD Feeds EVLA Feed/FE PDR February 12-13, 2002

  44. Comparison of 75" OD and 62" OD Feeds EVLA Feed/FE PDR February 12-13, 2002

  45. The hybrid lens feed EVLA Feed/FE PDR February 12-13, 2002

  46. Measured Pattern – Current Feed EVLA Feed/FE PDR February 12-13, 2002

  47. Corrected Pattern – Current Feed EVLA Feed/FE PDR February 12-13, 2002

  48. Measured Pattern – Current Feed EVLA Feed/FE PDR February 12-13, 2002

  49. Corrected Pattern – Current Feed EVLA Feed/FE PDR February 12-13, 2002

  50. Comparison: New Design & Current FeedL-Band EVLA Feed/FE PDR February 12-13, 2002

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