Motivation: Increase Field of View for Radio Telescopes

Projects and Achievements: World's Best Array Feed System

System Block Diagram

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305m Arecibo Telescope in 2013

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100m Green Bank Telescope in 2015

Representative Journal Publications:

  1. D. Anish Roshi, W. Shillue, B. Simon, K. F. Warnick, B. Jeffs, D. J. Pisano, R. Prestage, S. White, J. R. Fisher, M. Morgan, R. Black, M. Burnett, J. Diao, M. Ruzindana, V. van Tonder, L. Hawkins, P. Marganian, T. Chamberlin, J. Ray, N. M. Pingel, K. Rajwade, D.R. Lorimer, M. A., McLaughlin, A. Rane, J. Castro, W. Groves, L. Jensen, J. D. Nelson, T. Boyd, and A. J. Beasley, “Performance of a highly sensitive, 19-element, dual-polarization, cryogenic phased array feed”. The Astrophysical Journal, vol. 155, no. 5, pp. 202, Apr. 2018.

  2. J. Diao, and K. F. Warnick. “Antenna loss and receiving efficiency for mutually coupled arrays.” IEEE Trans. Antennas Propag., vol. 65, no. 11, pp. 5871-5877, Nov. 2017.

  3. J. Diao, and K. F. Warnick. “On the bandwidth gap between the array feed and cluster feed regimes for broadband multifeed system.” IEEE Trans. Antennas Propag., vol. 64, no. 6, pp. 2207-2216, Jun. 2016. (This paper has been nominated as best paper award for IEEE Trans. Antennas Propag in 2016.)

  4. N. Erickson, J. Diao, K. F. Warnick, and G. Narayanan. “Analysis of a 64-element mm-wave cryogenic phased array feed for the Green Bank Telescope.” IEEE Trans. Antennas Propag., in preparation.

While a large amount of money has been spent to build a large radio telescope, the performance of the radio telescope such as field of view, aperture efficiency, and system noise temperature is limited to the feed system performance. Compared to the traditional single horn antenna, the field of view of the radio telescope can be largely increased using focal plane digital beamforming array (phased array feed).

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Developed high sensitive focal plane phased array feeds system including arrays, RF circuits and signal processing for the world most famous radio telescopes including the 100-meter Green Bank Telescope (the largest fully steerable radio telescope) and the 305-meter Arecibo Telescope (the second-largest radio telescope).


Projects (NSF founded): 

  • Cornell/BYU L-band phased array feed for the 305-meter Arecibo Telescope.

  • Umass/BYU W-band phased array feed for the 100-meter Green Bank Telescope.

  • BYU/NRAO L-band phased array feed for the 100-meter Green Bank Telescope.



  • The world's most sensitive phased array feed system. System noise temperature over aperture efficiency at L-band is 25.4K, which is about two times better than the other state-of-the-art phased array feeds that is equivalent to increase the telescope diameter by about 1.4 times. (My works: antenna and array modeling, design, fabrication and measurement.)

  • The world's first phased array feed operated at mm-wave. (My works: system modeling, RF circuits, digital beamforming, and system measurement.)

  • Characterized inherent bandwidth gap between phased array feeds (beamforming) and cluster feeds (no beamforming). This work was nominated as the best paper award for IEEE Trans. Antennas Propag. in 2016.

  • Proposed new antenna terminologies of effective loss and radiation resistances for array antennas similar to the resistance of a single antenna.

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