# EMC Fundamentals

“The most difficult subjects can be explained to the most slow-witted man if he has not formed any idea of them already; but the simplest thing cannot be made clear to the most intelligent man if he is firmly persuaded that he knows already, without a shadow of doubt, what is laid before him.” – Leo Tolstoy, 1897

The subject of EMC has long been treated as ‘black magic’, ‘dark art’ or ‘something cannot be explained’. This long-standing misconception is due to lots of historical reasons, education is one thing, and using the correct tool to explain the physical world is another. The problem is as human beings, we find it so hard to change a habit. Once an idea is formed, it will take lots of effort and persuasion to change one’s mind or interpretation of something. Especially if the person is considered as an expert in his or her field.

The EMC Fundamentals section aims to demystify EMC by using simple physics and maths model so one can truly appreciate what is really happening behind the electromagnetic phenomenon. This might mean some of the ideas will conflict with what you learnt in school or from work, but it is worth taking a different view when something didn’t work. The circuit theory has a very deep root in the engineering world, but it has its limits, particularly when everything in the modern electrical engineering world is getting faster.

To make a point here, we all know that current flowing from positive side of a battery to a load and return to the negative side of the battery is a flawed idea. Because electrons flow the other way around. But due to historical reasons, we just stick with this idea, knowing its flaw and adapt. You will soon find lots of the things we learnt from circuit theory are flawed to some extent (they work most of the time because the circuit is running at DC or at low frequency range).

We hope you enjoy learning the basics of electromagnetic phenomenon, because it is really a mind stretching exercise. Once you grasp the fundamentals, applying the right techniques to fix an EMI issue is never a magic anymore, and you will truly be able to understand the language of an EMC engineer.

Written Work

Make Sense of Attenuation

Make Sense of Common-mode Noise

Insertion Loss and Filter Performance

Capacitors: Theory and Applications

Video Demo

Understand bandwidth – Why do we need an RF current probe?

Understand Loop Inductance – Simulation enables you to see what has been going on

Impedance vs frequency curve of a ceramic capacitor