Predavanje "Metamaterials – from application to realization"

Metamaterials – from application to realization
In the first part of the talk a new metamaterials design methodology will be discussed.  The specific processes that must take place in design of such materials for practical systems will be demonstrated on a simple example:  an infinite line source above perfect ground-plane for low-profile VHF/UHF antenna applications.
Second part of the talk will discuss analysis and physical aspects of a metamaterial slab of wire-split ring resonators (W-SRR). Metamaterials with W-SRR have been treated extensively in the past, including efforts to retrieve their effective homogeneous constitutive parameters.  Most papers derive these parameters from slabs with a very small number of layers, often only one or two layers, or sometimes even one single cell.  However it is difficult to accurately determine the bulk material properties from single layer data. We are not aware of any comprehensive efforts which explore the accuracies obtained by these extrapolation techniques.
Therefore in this study we have analyzed and characterized a metamaterial slab of periodic W-SRR elements with a number of layers ranging from 1 to 12.  We simulated this structure with High Frequency Structure Simulator (HFSS) and, when using the standard transmission line method, showed that a minimum of 8 layers is required to converge to accurate effective values for the relative permittivity  εr and permeability µr.  In addition we discuss the loss mechanism in the DNG region, spatial dispersion and depolarization effects which impose practical limitations on this “conventional” element.

Biography of  Boris Tomasic
Boris Tomasic was born in Rijeka, Croatia, on August 8, 1945.  He received the Dipl. Ing. degree in electrical engineering from Fakulteta za Electrotehniko, Univerza v Ljubljani, Slovenia, in 1971 and the M.S. and Ph.D. degrees in electrical engineering from Polytechnic Institute of New York, Brooklyn, NY, in 1975 and 1981, respectively.
From 1975 to 1980, he was a Research Assistant at Polytechnic Institute of New York, performing research on conformal and planar array antennas.  Since 1981, he has been with the Air Force Research Laboratory, Sensors Directorate, Electromagnetics Technology Directorate, WPAFB, OH.  Presently, he is the Technical Advisor in Antenna Technology Branch.  This branch has the responsibility for developing the technology base for antennas within the Air Force.  Dr. Tomasic is responsible for planning and conducting research and development studies in the field of electromagnetics radiation, propagation and diffraction.  His research interest is in the areas of antenna theory, planar and conformal phased arrays for airborne and space applications, and metamaterials.
From 1981 to 1990, he was adjunct faculty member at the University of Massachusetts teaching graduate courses in electromagnetics and antenna theory.  Dr. Tomasic is a member of Sigma Xi, URSI Commision B, and senior member of IEEE.  From 1986 to 1989 and from 1987 to 1999 he was  an associate editor for IEEE Transactions on Antennas and Propagation.  He is the Air Force Research Laboratory Fellow.