August 24, 2012
Colloquium Speaker: Dan Sievenpiper
Professor Dan Sievenpiper joined the UCSD faculty in 2010. He received his BS in 1994 and his PhD in 1999 from UCLA, where he studied photonic crystals and periodic structures, and invented the high impedance electromagnetic surface. After graduation, Dan joined HRL (the former Hughes Research Laboratories) in Malibu, CA. During the following 11 years, he developed new electromagnetic structures, with an emphasis on small, conformal, tunable, and steerable antennas. Dan held a variety of technical positions at HRL, including serving as the director of the Applied Electromagnetics Laboratory. At UCSD, his research is focused on artificial media, and the integration of active electronics with electromagnetic structures and antennas to enable new capabilities. In 2008, Dan was awarded the URSI Issac Koga Gold Medal. In 2009, he was named as a Fellow of the IEEE. Dan has more than 70 issued patents and more than 60 technical publications.
Colloquium Topic: Artificial Impedance Surfaces: Passive, Active, and Nonlinear Periodic Structures for Controlling Electromagnetic Surface Currents
In this talk, we will describe artificial impedance surfaces, their design, their limitations, and their applications. Beginning with the origins of these structures, we will develop a basic understanding of their behavior and the properties that can be expected with practical designs. We will describe how these structures evolved into tunable impedance surfaces for beam steering, and holographic artificial impedance surfaces. We will also discuss several topics of current research in this area, such as anisotropic impedance surfaces for surface wave cloaking of features on metallic bodies. These will be practical cloaking structures for realistic applications, not the science fiction that you see in the popular press today. We will then describe nonlinear absorbing surfaces for high-power microwave applications, and how nonlinear coatings can decouple the high-power absorption properties of a surface from its small signal scattering behavior. Finally we will discuss active impedance surfaces based on non-Foster circuits, and their use as superluminal guiding structures for thin, broadband antennas.