RADLAB Seminar

Novelties of Reflectarray Antennas: Legitimate Children of Reflector and Array Antennas

Yahya Rahmat-SamiiNorthrop Grumman Chair Distinguished ProfessorUCLA

Broadly speaking a reflectarray antenna is a legitimate child of a reflector and an array antenna. Reflectarray's major role is to synthesis any desired scattered wavefront from a given incident wavefront. Both reflector and phased array antennas do this as well. In reflector antennas one typically utilizes curved surfaces and in phased arrays one uses the element phasing to achieve the desired radiating wavefront. A reflectarray will do this by first being a planar structure rather than a curved structure and secondly by creating the desired element phases through the element topology instead of phase shifters. These two unique features make a reflectarray antenna a potentially very interesting and useful radiating device. Typically a reflectarray is composed of a number of radiators on a planar surface (for example patches of various sizes) that imposes a specified amount of phase to the reflected field from a feed or multiplicity of feeds in order to create any desired radiation patterns into space. In this talk we will address the following topics: (a) The origin and history of reflectarrays, (b) Understanding the fundamental concepts behind their functionality, (c) The design approaches and performance characterizations including novel graphical visualizations, (d) Bandwidth limitations and other potential short comings, (e) Diverse applications in mimicking performance of conventional curved reflector antennas, elliptical or hyperboloidal subreflectors, wavefront correcting mirrors and others, (f) Reconfigurable reflectarray designs using MEMS, (g) Novel simulation and measurement results, and (h) Recent advances and future applications in microwave, mm-waves, cubesats and optical regimes.
Yahya Rahmat-Samii is a Distinguished Professor, holder of the Northrop-Grumman Chair in electromagnetics, member of the US National Academy of Engineering (NAE), winner of the 2011 IEEE Electromagnetics Field Award and the former chairman of the Electrical Engineering Department at the University of California, Los Angeles (UCLA). Before joining UCLA, he was a Senior Research Scientist at Caltech/NASA's Jet Propulsion Laboratory. Dr. Rahmat-Samii was the 1995 President of the IEEE Antennas and Propagation Society and 2009-2011 President of the United States National Committee (USNC) of the International Union of Radio Science (URSI). He has also served as an IEEE Distinguished Lecturer presenting lectures internationally.

Dr. Rahmat-Samii is a Fellow of the IEEE, AMTA, ACES, EMS and URSI. Dr. Rahmat-Samii has authored or co-authored over 1000 technical journal articles and conference papers and has written over 35 book chapters and five books. He has over fifteen cover-page IEEE publication papers. In 1984, he received the Henry Booker Award from URSI, which is given triennially to the most outstanding young radio scientist in North America. In 1992 and 1995, he received the Best Application Paper Prize Award (Wheeler Award) of the IEEE Transactions on Antennas and Propagation. In 1999, he received the University of Illinois ECE Distinguished Alumni Award. In 2000, Prof. Rahmat-Samii received the IEEE Third Millennium Medal and the AMTA Distinguished Achievement Award. In 2001, Rahmat-Samii received an Honorary Doctorate Causa from the University of Santiago de Compostela, Spain. In 2001, he became a Foreign Member of the Royal Flemish Academy of Belgium for Science and the Arts. In 2002, he received the Technical Excellence Award from JPL. In 2004, he received the 70th Anniversary of the Faculty of Engineering of University of Tehran Distinguished Alumni Award. He received the 2005 URSI Booker Gold Medal presented at the URSI General Assembly. He is the recipient of the 2007 Chen-To Tai Distinguished Educator Award and the 2009 Distinguished Achievement Award of the IEEE Antennas and Propagation Society. He is the recipient of the 2010 UCLA School of Engineering Lockheed Martin Excellence in Teaching Award and the 2011 campus-wide UCLA Distinguished Teaching Award. In 2015, he received the Distinguished Engineering Educator Award from The Engineer's Council. In 2016, he received the John Kraus Antenna Award of the IEEE Antennas and Propagation Society and In 2017, Rahmat-Samii received the ACES Computational Electromagnetics Award.

Prof. Rahmat-Samii has had pioneering research contributions in diverse areas of electromagnetics, antennas, measurement and diagnostics techniques, numerical and asymptotic methods, satellite and personal communications, human/antenna interactions, RFID and implanted antennas in medical applications, frequency selective surfaces, electromagnetic band-gap structures, applications of the genetic algorithms and particle swarm optimizations, etc., His original antenna designs are on many NASA/JPL spacecrafts for planetary, remote sensing and Cubesat missions (visit http://www.antlab.ee.ucla.edu/). Prof. Rahmat-Samii is the designer of the IEEE AP-S logo which is displayed on all IEEE AP-S publications.

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