EMC Question of the Week: September 15, 2025

shapes labeled source, coupling path, and receptor (victim)

How many fundamental EM coupling mechanisms are there?

  1. two
  2. three
  3. four
  4. more than four

Answer

The correct answer is “c.” The four fundamental EM coupling mechanisms are:

1. Common Impedance Coupling (aka Conducted Coupling)
2. Electrical Field Coupling (aka Capacitive Coupling)
3. Magnetic Field Coupling (aka Inductive Coupling)
4. Radiated Coupling

Collectively, these coupling mechanisms describe all possible coupling paths between EMI sources and EMI receptors. Understanding these coupling mechanisms and recognizing when they are likely to be important is absolutely essential for anyone involved in EMC design or troubleshooting. Don't fall into the trap of thinking that EM interactions are either conducted or radiated. Don't let anyone tell you that EMC design is mostly about following a set of rules. Don't believe it when you hear that experience is more important than a basic knowledge of EM theory. 

Good engineering starts with a knowledge of the fundamentals. For EMC engineers, no skill is more important than identifying and (to some extent) quantifying the four EM coupling mechanisms in circuit boards and systems.    

Have a comment or question regarding this solution? We'd like to hear from you. Email us at This email address is being protected from spambots. You need JavaScript enabled to view it..