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New Technology for Array Telescopes

New Technology for Array Telescopes. cm wavelength arrays R. D. Ekers National Radio Science Meeting, Boulder, 7 Jan 2000. Jansky 1937 - the beginning. Radio Telescope Sensitivity. Exponential increase in sensitivity x 10 5 since 1940 ! 3 year doubling time for sensitivity.

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New Technology for Array Telescopes

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  1. New Technology for Array Telescopes cm wavelength arrays R. D. Ekers National Radio Science Meeting, Boulder, 7 Jan 2000

  2. Jansky 1937 - the beginning Radio Telescope Sensitivity • Exponential increase in sensitivity x 105 since 1940 ! • 3 year doubling time for sensitivity R D Ekers

  3. Exponential Growth • Livingstone Curve • Blewett, Brookhaven 1950 • Fermi 1954 • Livingstone 1962 • De Solla Price 1963 • exponential growth • Little science, big Science • Moore’s Law (1965) • computing power doubles every 18months R D Ekers

  4. No technical reason not to continue this growth Exponential increase in sensitivity x 105 since 1940 ! 3 year doubling time for sensitivity SKA stations in landscape Radio Telescope Sensitivity SETI Institute UC Berkeley Path to the Future Future Radio Telescopes R D Ekers

  5. Radio Astronomy • Provides unique information about the Universe • non-thermal processes: quasars, pulsars, ... • highest angular resolution: VLBI • low opacity: Galactic nuclei R D Ekers

  6. UPGRADES VLA (7mm, 4m) Merlin WSRT Penticton Arecibo (optics) Parkes (FPA) ACTA (10-100GHz) Hat Creek IRAM ..... COMPLETING VLBA GMRT GBT [300’ upgrade?] 1990's the decade of the upgrades NEW STARTS • mmA (ALMA) • SKA • LOFAR, 1hT, KARST... R D Ekers

  7. International Megaprojectsin Radio Astronomy • Dramatic improvements in sensitivity • VLA upgrade and other smaller projects • $US200M • mm arrays in the Atacama dessert in Chile (ALMA) • 1998-2005: $US700M • Redshifted molecular lines • One Square Km telescope at cm wavelengths (SKA) • 2008-2015: $US500M R D Ekers

  8. COBE satellite NASA “Primordial soup” - matter and energy radio ? Square-Kilometre Array “Dark Ages” - before the stars Early galaxies - stars light up light Hubble Space Telescope NASA / ESA Telescopes Look Back in Time

  9. SKA 2008 VLA 1980 Future Sensitivity HST R D Ekers

  10. Communications developments Radio Telescopes of the Future • HEMT receivers • wide band, cheap, small and reliable • Can build low noise systems with many elements • Focal plane arrays • Field of view • Interference rejection • adaptive nulling can work in single dishes and arrays • More computing capacity • computing power doubles every 18months (Moore’s Law) R D Ekers

  11. MMIC (Transistors) • GAs -> InP • Extend frequency range 1GHz - > 150 GHz • Wide instantaneous bandwidth • Large scale integration • Complete receiver system on one chip • Focal plane arrays • Receivers embedded in feed structure • Integrated photonics R D Ekers

  12. Consumer Cryogenics • Driven by changes in the communications industry • cryogenics in all communications towers • Inexpensive low noise receiver packages • Superconducting filters • interference mitigation R D Ekers

  13. Photonics • signal transport via fibers • low loss, high bandwidth, immunity to interference • needs inexpensive transmitters/receivers • Eg Vicsel optical modulator $10-20 • LO transport via fibres • local (on chip) LO generation • Integrated photonics to reduce component count • Time delay arraying • Filters • fibre gratings for tunable wide band microwave filters R D Ekers

  14. Installing the Parkes 21cm Multibeam Receiver R D Ekers

  15. The Multibeam FPA Receiver • 13 beams in focal plane • HI Survey of the local Universe • Complete HI selected galaxy catalog out to z = 0.04 • low-surface brightness galaxies • high-velocity cloud survey • 21cm pulsar survey • 7x faster than any previous survey • FPA makes all sky surveys possible at higher frequencies R D Ekers

  16. Forte satellite: 131MHz Terrestrial Interference R D Ekers FORTÉ satellite: 131 MHz

  17. The RFI Challenge • Sensitivity to increase (100x) • Whole of radio spectrum needed • early Universe studies require “whole” spectrum to see redshifted lines • but only to “listen”, and only from a few locations. • 2% of spectrum is reserved for Radio Astronomy • LEO telecom satellites a new threat • no place on Earth free frominterference from sky • current regulations will be inadequate R D Ekers

  18. - eg pulsar dispersion  Antenna arrays can cancel RFI using all these ! RFI fundamentals • The interference and radio astronomical signals can differ in all these parameters • Frequency • Time • Position • Polarization • Distance • Positivity • We can use one or more of these to separate the interference from the astronomical signals In this phase space the radio sky is very empty!

  19. Adaptive array nulling R D Ekers

  20. Digital • Using Moore’s law • Wide bandwidth signal processing • 2-20GHz • Software radio’s • 20GHz in next decade • consumer market driven • Interference mitigation • Access to entire spectrum • Smart Antennas • Image processing • Can make array’s easy to use R D Ekers

  21. Microprocessor performance R D Ekers

  22. Object Oriented Software • AIPS++ • Astronomical Image Processing System • C++, scripting, GUI’s, libraries, toolkits and applications • Designed by a team of astronomers and programmers • Public release mid 99 • Developed by an international consortium of observatories R D Ekers

  23. Square Kilometer Array • Current large telescope technology dates from 1960/70’s • Era of facilities upgrades approaching its end • Large increase in sensitivity is needed (100x) • epoch of first stars and galaxies • New challenges: • cost • frequency coverage • man-made interference • Technology shift will be required... R D Ekers

  24. Square km telescope: the concept • One square km radio telescope (1kT) in 2010 • 2002 detailed design, prototypes • 2007 construction • 2012 operations • Frequency range 0.03 - 20GHz • Sensitivity 100 x VLA • Multibeam (at lower frequencies) • Need innovative design to reduce cost • International funding unlikely to exceed $500m • 106 sq metre => $500 / sq metre • cf VLA $10,000 / sq metre • GMRT $1,000 / sq metre R D Ekers

  25. Multi beams Element antenna pattern Station antenna patterns Synthesized beams 16 • Observing teams with their own beams • like particle accelerator, but can have all beams simultaneously • Observe before trigger ! • Using baseband buffer 12 8 4 NFRA 1998

  26. Who is Involved ? • Netherlands: SKAI Phased array • NFRA • Australia: 1kT Luneberg lens array • CSIRO • USA: 1hT Small dish array • SETI, UCB, MIT… communications antennas • Canada: LAR Large adaptive reflectors • DRAO long F/D • China: KARST Large adaptive reflectors • BAO spherical • India: -- Medium size dishs • NCRA fine mesh • UK : -- • Jodrell Bank

  27. Netherlands - NFRA:One Square Meter Phased Array • > octave BW: • 1.75 - 4 GHz • 64 active elements • 2 full sensitivity RF beams • 2 full sensitivity adaptive, digitally formed beams • adaptive algorithm on IC (CORDIC) NFRA 1998 R D Ekers

  28. Square-Kilometre ArrayNetherlands 1kT - PMSEIC WG http://www.nfra.nl/skai/

  29. Luneburg Lens • Spherical lens with variable permittivity, er = (2 – r2) • A collimated beam is focussed onto the other side of the sphere • Beam can come from any direction R D Ekers

  30. Luneburg Lens antenna systems • Optim Microwave • A Commercial Luneburg Lens • www.optim-microwave.com R D Ekers

  31. Luneburg Lens All sky coverage multiple simultaneous beams Possible design 5-m spheres Each patch 100 m diameter 100s of patches Square-Kilometre Array CSIRO -Australia R D Ekers http://www.atnf.csiro.au/SKA/

  32. 1hT SETI Institute - UC Berkeley • SETI Institute &UC Berkeley • ~500 x 5 m diameter dishes • 1 ha effective area • 1–10 GHz • 4o FOV at 1 GHz http:// www.seti.org

  33. Large Adaptive ReflectorNRC - Canada • 200m diameter stations • flat panels • large F/R • receivers supported by balloon • 500m above reflector • 250 MHz to 22 GHz. R D Ekers http//www.drao.nrc.ca/science/ska/

  34. KARST Large Radio Telescope - China • BAO - China • Kilometer square Area Radio Synthesis Telescope • 500m diameter • Spherical reflector • 300m locally parabolic http://www.bao.ac.cn/bao/LT/

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