EM Coupling Mechanisms

Coupling mechanisms are explained using the concept of electrically short structures. The authors begin by introducing a mathematical concept of a wave and then showing that the time‐varying EM fields propagate as waves. Every EMC interference problem consists of three basic parts: the interference source, the coupling mechanism, and the susceptible system. The authors focus on the coupling mechanisms between the interference source and the susceptible system. The basic model for the capacitive coupling between two conductors is shown. When two circuits are in the vicinity of one another, a signal propagating in one circuit can induce a signal in another circuit, due to capacitive (electric field) and inductive (magnetic field) coupling between the circuits. This phenomenon is referred to as crosstalk. Two PCB traces in a microstrip configuration are separated from each other by distance and from the ground plane by a distance.