EMC Question of the Week: November 6, 2017

Circuits sharing a common return conductor

The only EM coupling mechanism that can result in crosstalk at DC (0 Hz) is,

  1. common impedance coupling
  2. electric field coupling
  3. magnetic field coupling
  4. radiated field coupling

Answer

The correct answer is "a". When the common impedance is a common resistance, common impedance coupling (also called conducted coupling) is independent of frequency. All other forms of EM coupling are generally frequency dependent and are zero at DC.

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