An Introduction to James C. Rautio’s Article on James Clerk Maxwell

The following article written by James C. Rautio is a thorough and concise description of the life and accomplishments of James Clerk Maxwell and what led him to the exposition of his famous laws of electromagnetism. It was previously published in the IEEE Microwave Theory and Techniques Society Magazine. Jim Rautio is with Sonnet Software in Syracuse, New York, which is one of the leading producers of software for numerical analysis of electromagnetics (EMC) problems. Everything we do in the discipline of EMC as well as in a myriad of uncountable other applications is governed by these laws which are generally referred to as “Maxwell’s Equations”.
As a Distinguished Lecturer for the MTT Society, he chose the topic of “The Life of James Clerk Maxwell.” It is important for students and practitioners to know the history of electrical engineers who have made substantial contributions to our profession. These early researchers performed their experiments using the crudest of experimental apparatus by today’s standards. Yet, the fundamental laws they formulated have remained unchanged for 200 years!
We often lose sight of the fact that in every aspect of our daily EMC work we are “solving Maxwell’s equations.” Perhaps this is because we can often “get away with” using lumped circuit ideas (Ohm’s law) and Kirchhoff’s laws and don’t appear to be solving Maxwell’s equations when in fact we are. These are approximations to Maxwell’s equations valid only where our circuits are electrically small (i.e., maximum physical dimensions much less than a wavelength). With digital processor clock and data speeds today entering the gigahertz range and risetimes/falltimes of the pulses in the sub-nanosecond range, these lumped-circuit notions often do not work any longer since the circuits dimensions (such as PCB land lengths) are becoming electrically long. The physical dimensions of PCBs and the lands on them have not changed substantially, but the spectral content of the signals carried by them has! Therefore, in the electronics of the future we have no choice but to give Maxwell’s equations a fresh look. Hence, it is fitting that our science has come around again to these fundamental laws of Maxwell. EMC

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