Title: EM currents for antenna optimization, near-field diagnostics, and EMF exposure
Speaker: Mats Gustafsson, Department of Electrical and Information Technology, Lund University, Lund
Abstract: In this presentation, it is shown how optimization of EM currents can be used in antenna design, near-field imaging, and EMF exposure estimation. Antenna design can be considered as an art of shaping and choosing materials to produce a desired current distribution on the antenna structure. Antenna current optimization is a tool to determine an optimal current distribution which can be used for physical understanding, as a priori estimates of the possibilities to design antennas, physical bounds, and as figures of merits for antenna designs. Antenna current optimization is particularly useful for small antennas for which the Q-factor and efficiency are of primary importance. In this presentation, antenna current optimization to determine fundamental bounds on the Q-factor, efficiency, gain, and capacity is presented. Moreover, it is demonstrated how the approach can be modified to determine generalized mode expansions.
Reconstructions of field and current distributions are useful in applications such as non-destructive diagnostic of antennas and radomes and assessment of EMF exposure. In this presentation, we show how the field and current distribution can be reconstructed and visualized from near- and far-field measurement data. We discuss compressive sensing techniques for inverse source problems to accurately reconstruct electromagnetic fields on a surface or volume from near-field measurements. We illustrate how the techniques can be used in antenna and radome diagnostics to, for example, identify faulty parts.
Title: Electromagnetic design and optimization
Speaker: Sven Nordebo, Department of Physics and Electrical Engineering, Linnaeus University, Växjö
Abstract: I will give an overview and present some results and examples from two different research topics
concerning electromagnetic design and optimization. The first topic is related to a research project (VR 2010-2012) dealing with dispersion modeling and analysis for multilayered open coaxial waveguides. The objective was to study fundamental wave modeling for signal estimation on lossy transmission lines and the main application was for HVDC power cable modeling, measurements and fault localization.
The second topic is part of an ongoing project (SSF 2014-2019) "Complex analysis and convex optimization for EM design” and is concerned with fundamental bounds on absorption and scattering in plasmonics. In particular, explicit bounds are given on the optimal plasmonic resonances in sub-wavelength spheres embedded in lossy media, giving insight into the realizability of optimal resonances based on standard metals. Finally, a general approach to system approximation based on convex optimization will be described. Here, a canonical example is to study the realizability of a passive metamaterial designed to approximate an ”ideal” plasmonic target dispersion function over a given bandwidth.
EA, lecture hall, Hörsalsvägen 11, Campus Johanneberg
17 September, 2018, 13:15
17 September, 2018, 15:00