Dr. Edmund Miller

All external electromagnetic fields arise from the process of radiation. There would be no radiated, propagated or scattered fields were it not for this phenomenon. In spite of this self-evident truth, our understanding of how and why radiation occurs seems relatively superficial from a practical viewpoint. It’s true that physical reasoning and mathematical analysis via the Lienard-Wiechert potentials show that radiation occurs due to charge acceleration. It’s also true that it is possible to determine the near and far fields of rather complex objects subject to arbitrary excitation, making it possible to perform analysis and design of EM systems. However, if the task is to determine the spatial distribution of radiation from the surface of a given object from such solutions, the answer becomes less obvious.

One way to think about this problem might be to ask, were our eyes sensitive to X-band frequencies and capable of resolving source distributions a few wavelengths in extent, what would be the image of such simple objects as dipoles, circular loops, conical spirals, log-periodic structures, continuous conducting surfaces, etc. when excited as antennas or scatterers? Various kinds of measurements, analyses and computations have been made over the years that bear on this question. This lecture will summarize some relevant observations concerning radiation physics in both the time and frequency domains for a variety of observables, noting that there is no unanimity of opinion about some of these issues. Included in the discussion will be various energy measures related to radiation, the implications of Poynting-vector fields along and near wire objects, and the inferences that can be made from far radiation fields. Associated with the latter, a technique developed by the author called FARS (Far-field Analysis of Radiation Sources) will be summarized and demonstrated in both the frequency and time domains for a variety of simple geometries. Also to be discussed is the so-called E-field kink model, an approach that illustrates graphically the physical behavior encapsulated in the Lienard-Wiechert potentials as illustrated below. Brief computer movies based on the kink model will be included for several different kinds of charge motion to demonstrate the radiation process.

Biography:

Since earning his PhD in Electrical Engineering at the University of Michigan, Edmund K. Miller has held a variety of government, academic and industrial positions. These include Lawrence Livermore National Laboratory and Los Alamos National Laboratory. Academic appointments include Kansas University, Ohio University, Michigan Technological University and the University of Michigan. Industrial positions were with MB Associates in San Ramon, CA, the Rockwell Science Center in Thousand Oaks, CA, and the General Research Corporation in Santa Barbara, CA. Dr. Miller has been appointed as an AP Distinguished Lecturer for 2014-2016, and wrote the columns “PCs for AP and Other EM Reflections” from 1984 to 2000 for the Magazine of the Antennas and Propagation Society. He received (with others) a Certificate of Achievement from the IEEE Electromagnetic Compatibility Society for Contributions to Development of NEC (Numerical Electromagnetics Code) and was a recipient (with others) in 1989 of the best paper award given by the Education Society for “Computer Movies for Education.”

Various IEEE activities include serving as Editor or Associate Editor of IEEE Potentials Magazine and writing a regular column “On the Job,” for Potentials from 1997 to 2004 and a column “PCs for AP and Other EM Reflections. He was involved in the beginning of the IEEE Magazine “Computational Science and Engineering” for which he has served as Area Editor or Editor-at-Large. He has also served as an associate editor of Radio Science, the PIERS Journal, Journal of Electromagnetic Waves and Applications, the AP-S Magazine, and the International Journal of Numerical Modelling.

He was elected a member of the Electrical Engineering Academy of Michigan Technological University and is a Life Fellow of IEEE from which he received the Third Millennium Medal in 2000. He is also a Fellow of ACES from which he received ACES Applied Computational Electromagnetics award in 2014. His research interests include scientific visualization, model-based parameter estimation, the physics of electromagnetic radiation, validation of computational software, and numerical.