Far-field wireless power transfer (WPT) has been reconsidered in recent years as practical means to transfer power from outer space where satellites collect solar power with high efficiency using photovoltaic technology and then convert the power to microwaves for beaming to antenna farms at specific locations on earth. Conventional antennas have been the traditional microwaves transducers used for WPT applications. Almost all antennas that were considered for WPT applications were designed in the first place for communication applications where traditional antenna parameters such as gain, directivity and efficiency were considered the most critical. For WPT applications, however, the primary concern is to collect as much power as possible per footprint, based on specific polarization and incident angle.
Metamaterials are made of a three-dimensional ensemble of electrically-small resonators or particles. Metasurfaces are considered as a two-dimensional version of metamaterials. The resonance of each particle of a metamaterial or metasurface is fundamentally indicative of its ability to store energy. Metamaterials, therefore, can be effective energy collectors. n this presentation, I will demonstrate that metasurfaces can indeed be effective electromagnetic energy harvesters and can provide energy harvesting efficiency appreciably higher than what classical antennas can achieve. I will present metasurfaces composed of different types of resonators including split-ring resonators, electric-inductive-capacitive resonators and complementary split-ring resonators. I will show that it is possible to achieve energy absorption with approximately 100% efficiency. Simulation and experimental results will be provided for validation.
Omar M. Ramahi received the BS degrees in Mathematics and Electrical and Computer Engineering (Highest Honors) from Oregon State University, Corvallis, OR. In 1990, he was awarded the Ph.D. degree in Electrical and Computer Engineering from the University of Illinois at Urbana-Champaign. He worked at Digital Equipment Corporation (presently, HP), In 2000, he joined the faculty of the James Clark School of Engineering at the University of Maryland at College Park as an Assistant Professor and later as a tenured Associate Professor. At Maryland he was also a faculty member of the CALCE Electronic Products and Systems Center. Presently, he is a Professor in the Electrical and Computer Engineering Department, University of Waterloo, Ontario, Canada. He has authored and co-authored over 350 journal and conference technical papers on topics related to the electromagnetic phenomena and computational techniques to understand the same. He is a co-author of the book EMI/EMC Computational Modeling Handbook, (first edition: Kluwer, 1998, Second Ed: Springer-Verlag, 2001. Japanese edition published in 2005). Dr. Ramahi is an elected IEEE Fellow. In 2009, he served as a Co-Guest Editor for the Journal of Applied Physics Special Issue on Metamaterials and Photonics. From 2007-2015, he served as an Associate Editor for the IEEE Transactions on Advanced Packaging. From 2010-2012, he served as an IEEE EMC Society Distinguished Lecturer. In 2014, he served as a Guest Editor for the journal Sensors, special issue on Metamaterial-Inspired Sensors.