Report on the IEEE EMC Society 2003 University Grant Program Awarded to the Department of Electrical and Computer Engineering at The Citadel, Charleston, South Carolina

EMC education has long been a pioneering effort in engineering schools around the world. The costs of creating a laboratory coupled with a lack of instructors with training and experience in EMC has substantially constrained the development of courses that teach this vital field. The annual award of a $10,000 grant by the IEEE EMC Society to an academic institution for the establishment of a course in the principles and practices of EMC has done much to improve the situation. In June 2003, we were pleased to learn from John Howard that the grant for that year had been awarded to The Citadel in Charleston, South Carolina. This article details the elements of the course and laboratory that were consequently created.
The Citadel was founded in 1842, and the Department of Electrical and Computer Engineering was established there in 1941. It offers two coeducational, undergraduate-only programs. The daytime program educates students in a military setting as members of the South Carolina Corps of Cadets. The evening program is offered in a nonmilitary environment to students from the Coastal South Carolina region, and is typically populated by students who are returning to school after significant work experience or military service.
The Citadel has been supportive of the effort to offer EMC education and began by granting funds for the purchase of a new Agilent spectrum analyzer with an optional tracking generator installed. The department was able to obtain the donation of a surplus 8.5X20X8-ft. shielded chamber from a local military installation, and the school committed significant resources for the reconstruction and refurbishment of the room. Surplus absorptive material donated by NASA was installed to deaden the response of the chamber. A ground-floor classroom was converted to permanently house this laboratory.

Instructor Tom Jerse (standing) shows Cadets Dave Coisson, Ivan Puhalo, and Derek Hall (from left) how to use a spectrum analyzer for making radiated-emission measurements.

The course instructor, Tom Jerse, has extensive industrial experience in EMC design practice, troubleshooting, and education obtained both at Hewlett-Packard and Boeing. One of his primary goals in entering academia was to create an ongoing EMC course, and his first step was to earn a Ph.D in EMC under Clayton Paul at the University of Kentucky.
The course ELEC 425, “Interference Control in Electronics,” was added to The Citadel catalog as a permanent senior elective. The word “electromagnetic” was deliberately omitted from the course title because it tends to strike fear in many students. With the aid of the IEEE EMC Society grant, the course was first offered during the spring semester 2004 in two sections. Eighteen students enrolled in the day section and twelve enrolled in the evening. These numbers represent approximately 90% of the students who were eligible to take the course. The prerequisites for the ELEC 425 course are all required junior-level courses: a one-semester introduction to electromagnetics, a course in linear systems, and a second course in digital design. The electromagnetics course primarily covers electrostatics along with Faraday’s Law. A few of the students had taken an elective course during the summer that discusses time-harmonic fields, but two of the lectures in the EMC course were used to bring everyone up on concepts such as wave propagation and wave impedances. This material was well supported by our textbook, Introduction to Electromagnetic Compatibility, by Clayton R. Paul.
The primary thrust of the course is to provide the students with the principles of good EMC design practice backed by enough relevant theory to explain their basis. A second goal is to provide a serviceable background, sufficient for those who might wish to engage in the graduate study of EMC. As a one-semester course, the scope of the EMC field had to be narrowed. The context of electronic product design was chosen for the exposition of the design practices. Areas such as frequency management and the effects of interference in communications systems and multi-emitter platforms were not covered. Because EMC design is in many ways the orchestration of current flow, its visualization became a major theme of the course.

Setting up a test sample for a radiated emissions experiment.

The IEEE EMC Society funds were used to help outfit our laboratory. A broadband biconalog antenna and preamplifier were purchased for use in the anechoic chamber along with a line impedance stabilization network (LISN) to measure conducted emissions. Probes and cables were obtained, and a small portion of the funds was used to acquire a commercial software package that enables the creation of animated 3D plots of time-varying functions for use in explaining some of the field concepts.
A vital part of the course was the use of the laboratory for a series of experiments that reinforced the theory as only practice can. Because the three-hour course as scheduled does not explicitly allocate time for a laboratory, several mini-labs were included. The students were divided into teams of three, and each experiment took approximately twenty minutes to perform. Only two lecture periods were allocated for mini-labs, but with the number of labs and the relatively large enrollment, several of the teams worked at other arranged times to complete the experiments. The incorporation of the optional tracking generator in our spectrum analyzer facilitates experiments involving crosstalk, current distribution, and shielding effectiveness measurements.
The course material encompassed the following areas:

1) Introduction and motivation for EMC study
Although a few of the evening students had encountered EMI problems in their work or military experience, the majority of students needed to learn the vital importance of EMC for the reliability and marketability of electronic products. Several real-world anecdotes where the reliability, safety, or cost of a product was dramatically compromised by EMI, served to motivate interest in the material.
2) Government regulations
Because the course emphasis is placed on design techniques, the coverage of regulations was relatively brief. The students learned the various categories of EMC regulations and the Class-B limits for both radiated and conducted emissions.
3) Measuring radiated emissions
The difference between near- and far-field measurements was presented, along with measurement procedures that account for antenna factors, preamplifier gains, and cable losses. A laboratory experiment quantifying and comparing to regulatory limits the emissions from a battery-powered digital clock circuit reinforced the concepts.
4) Crosstalk
Crosstalk was presented primarily from the point of view of signal integrity, but in doing so the basic principles of controlling radiated emissions were revealed. The material included common-impedance coupling, situations where electric-field coupling dominates, magnetic field coupling, and mixed coupling. The students were provided MATLAB routines written by the instructor that computed the mutual inductances and capacitances between a specified array of parallel conductors. Homework assignments had the students adjust the geometry of various configurations to discern some general principles about the relationship of layout to crosstalk. A laboratory experiment demonstrated the effect of termination impedances on crosstalk.
5) Cables: Applications and side effects
This section introduced twisted pair, ribbon cables, and various types of shielded cable and characterized them in terms of crosstalk and radiated emissions. Substantial attention was paid to the practical aspects of grounding and potential problems such as ground loops. Key to this discussion was the development of an intuitive understanding of the frequency-dependent distribution of return current over multiple paths, with the important role played by the skin effect. The characteristics and applications of ferrite devices were also presented.
6) EMC characteristics and layout of digital circuits
The impacts of circuit layout on signal integrity and radiated emissions were discussed. As with cables, an understanding of the distribution of return current flow was the most crucial skill developed. Original analysis software based on the Partial-Element Equivalent Circuit (PEEC) method that generates current maps proved helpful in this task. Some basic transmission line theory was introduced, and MATLAB software for computing the characteristics of various microstrip and stripline configurations was provided for numerical experiments. Several decoupling arrangements and their potentially resonant behavior were also covered.
7) Conducted emissions and immunity
This section detailed the need for and methods of controlling conducted emissions as well as their measurement with a LISN. Practical aspects of power-line filter design and installation were discussed. Various transient suppression devices were contrasted to illustrate their use in product protection.
8) Radiated immunity
After a discussion of the relatively dense electromagnetic environment that exists today, the theorem of reciprocity was invoked to show that the techniques learned to control emissions also enhanced radiated immunity. Nonlinear effects such as rectification and their exacerbation by resonances were also presented.
9) Shielding
This section began with Schellkunoff’s transmission line analogy for analyzing the penetration of an electromagnetic wave through a shield wall. Next, a surface current model was presented to enable the students to visualize and quantify the effects of apertures. Finally, the concept of transfer impedance and the physical design parameters that influence it on a shield seam were given. Colorful field plots made using a method-of-moments program were presented to demonstrate the concepts of reflection, diffraction, and resonance.

The Student Evaluation of Instruction forms completed by the students at the end of the term showed the appreciation felt by the students for the course. Twenty-eight of the thirty students “strongly agreed” and the other two “agreed” with the statement “I learned a lot in this course.” Written comments reflected the feeling among the students that they were given the opportunity to learn valuable real-world material that is less commonly taught, and statements of gratitude including “A good use of IEEE funds” were frequent.
The Citadel appreciates the support of the IEEE EMC Society that hastened the development of this popular senior elective. It will be offered every spring semester. Work is ongoing to refine and create additional experiments, and a student programmer has been enlisted to enhance and modernize the user interface of various analysis programs. This development activity will enable additional numerical analysis experiments to be given to the students as homework in order to give them a better sense of the dependence of EMC behavior on various physical parameters. EMC

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