Rocky Mountain Chapter EMC Society

Our last meeting was

Can Just Anyone Understand Electromagnetic Fields?

Download the presentation here
Pictures from the meeting

Presenter: Professor Edward Kuester Department of Electrical and Computer Engineering, University of Colorado at Boulder

Date : September 22 2000

Time : 1:30 pm - 4:30pm

Location: National Center for Atmospheric Research Mesa Lab and Fleischmann Building, 1850 Table Mesa Drive, Boulder CO. Look for the Main Seminar Room. Directions

What we saw: This talk was part seminar, part tutorial, part give-and-take with the audience. Historically, an electrical engineer's education provided a solid background in circuit analysis, and touched somewhat on other subjects (like computers, power conversion, electromagnetics, etc.). Much of what a working engineer was called upon to do could be accomplished by building on this foundation of circuit theory. As our use of the frequency spectrum pushes ever higher (1 GHz computer processors, cell phones at microwave band, and so on), designs can no longer be made purely on the basis of classical circuit concepts. Professor Edward Kuester tells students in the beginning electromagnetics class that EM fields are really the basis of everything we do outside the quantum level in electrical engineering. Does this mean that you have to be an expert in EM to design anything these days? Or can the impact of Maxwell's equations be understood in a simpler way, using ideas already familiar from electric circuits?

Twenty-eight intrepid folks turned up to see Professor Edward Kuester emphatically gave a "yes" answer to the second question. He looked at several issues that arise in practical applications (use of computers to calculate fields, the effect of EM fields between neighboring circuits, and others) and tries to show how readily understood techniques of circuit analysis can be used to deal with these problems.

Professor Kuester started his talk right at the beginning - Maxwells Equations. He briefly reviewed the four sets of equations and showed that although most engineers are concerned with approximating Maxwells Equations, they are themselves an approximation of Quantum Electrodynamics. We then reviewed some of the basics of field theory as a reminder and as a nice lead into how, by keeping element size small with respect to a wavelength, lumped-circuit theory can be obtained from EM fields in the low frequency limit. Professor Kuester then travelled back in time to 1850 and introduced Lord Kelvin who developed the telegraphers equations, an analytical connection between circuits and fields. He then posed the question - Can we go the other way. That is from Fields to Circuits? The answer was yes by taking the finite difference approximation for Maxwells curl equations and do it for all three space directions. A circuit was then shown that approximated the field description with the advantage that the circuit can be described in Spice and used as a computing tool. Professor Kuester then discussed the numerical computation of fields with some of the advantages and drawbacks. Keeping to the focus of talk, Professor Kuester then analysed printed circuit traces and described a way of making a "real" circuit model that models the actual currents on the traces rather than fields that we have little interest in. That is when we learned about the PEEC or Partial Element Equivalent Circuit Method. Professor Kuester then walked us through the connection between fields and circuits and then really stirred up the pot with a discussion on Partial Inductance. Finally at the end of the talk, the question - Understanding?.We learned that equations for EM fields can be reduced to equivalent circuit equations. Professor Edward Kuester opened up the discussion with the audience and fielded questions for about an hour afterwards


Pictures from our September Meeting
Click on image to enlarge

Maxwell close to the heart??

ChasLeadsOff.jpg

An attentive audience

Answering Questions

The professor and BillR ponder deep thoughts!!

Making a serious point!!