Abstract:
Detecting extremely weak radio signals from deep space requires large reflector antennas and high sensitivity receivers. The key figure of merit for the receivers is survey speed, which is related to bandwidth, system noise temperature, reflector aperture efficiency and field of view. Compared to the traditional single feeds, phased array feeds with significantly expended field of view are considered as the next generation receiver systems for radio telescope. This talk outlines the theory, design and analysis of phased array feeds and the experimental test on the 305-meter Arecibo Radio Telescope and the 100-meter Green Bank Telescope. Additionally, sparse rotated aperiodic subarrays with low peak side lobe levels and design complexity are introduced for satellite communications.
At the beginning of my PhD program, I always had a dream about the possibility of making the aperture efficiency of the radio telescope larger than unity or superdirectivity. This question is answered by using a new method called Poynting streamlines that provides a unique way to understand the field energy distribution near a receiving antenna. This method can be used to generate the geometrical shapes of antenna effective area, predict practical superdirectivity and understand the mutual couplings of array antennas.
Biography:
Junming Diao received the B.S. and M.S. degrees in electrical engineering from the University of Electronic Science and Technology of China (UESTC), Chengdu, Sichuan, China, in 2009 and 2012, respectively. He expects to get his Ph.D. degree in electrical engineering from the Brigham Young University (BYU) on April, 2017. He has authored or coauthored many scientific articles and conference papers on phased arrays for radio astronomy observations and satellite communications, antenna theory, super-gain antennas and THz antennas. He was a candidate for the best paper award for IEEE Transactions on Antennas and Propagations in 2016, USNC-URSI travel fellowship Grant Award, outstanding thesis award in UESTC and Sichuan province in China. He is a member of IEEE.
