Date and Time Tue, April 14, 2015, 2:00 PM - 3:00 PM
Location SF B560

Huygens Metasurfaces for Directive Radiation — Devices and Concepts

Dr. Ariel Epstein

Lyon Sachs Postdoctoral Fellow, University of Toronto (EM Group / Prof. Eleftheriades)


Huygens metasurfaces, thin sheets of (subwavelength) electric and magnetic polarizable particles, have recently demonstrated impressive wavefront manipulation capabilities, e.g. engineered reflection, refraction, focusing, and polarization control. In principle, following the equivalence principle, by inducing the suitable electric and magnetic surface currents upon them, any desirable transformation between incident and transmitted fields can be realized. However, in contrast to beam or plane-wave manipulation, to harness this novel concept for antenna applications, integration of other types of excitations is required, e.g. localized sources. Moreover, it turns out that simply following the equivalence principle may result in a design containing lossy or active elements, usually undesirable.

In this talk we present a general methodology for designing Huygens metasurfaces which convert a given (arbitrary) source field to directive radiation towards a prescribed angle. Using the spectral representation of the sources, we show that two physical conditions are sufficient to guarantee the design is passive and lossless: local power conservation and local impedance equalization. Good agreement between semi-analytical predictions and numerical simulations is demonstrated by applying the design procedure to various source configurations.

In the second part of the talk we shed light on the mechanism underlying the operation of these devices. By employing the Floquet-Bloch theory to analyze the scattering properties of a (periodic) refracting Huygens metasurface, we show that its unique surface impedance modulation facilitates efficient coupling to the (desirable) refracted mode over a broad range of angles of incidence. An intuitive ray-optical model is assigned to the closed-form analytical results, establishing a path for ray-oriented synthesis (and analysis) of novel devices.

These results pave the way to efficient design of novel antenna devices based on Huygens metasurfaces.


Ariel Epstein received the B.A. degree in Computer Science from the Open University of Israel, and the B.A. degree in Physics and the B.Sc. degree in Electrical Engineering from the Technion – Israel Institute of Technology, Haifa, Israel, in 2000 and 2003, respectively. In 2013 he received his Ph.D. from the Technion for his thesis, titled "Rigorous Electromagnetic Analysis of Optical Emission of Organic Light-Emitting Diodes". His paper, "On the Relevance of Two-Dimensional Sources for Modeling Optical Emission from Layered Media" was the recipient of the Young Scientist Best Paper Award of the URSI Commission B International Symposium on Electromagnetic Theory (EMTS2013) held in Hiroshima, Japan, on May 2013.

He is currently a Lyon Sachs Postdoctoral Fellow at the University of Toronto in the Electromagnetics group under the supervision of Professor Eleftheriades. His current research interests include utilization of electromagnetic theory, with emphasis on analytical techniques, for novel applications, e.g. electromagnetic metamaterials , nanoelectronic devices, etc.