【 Weak current College 】 on electromagnetic coupling method of classification 】

Summary of a variety of coupling characteristics, calculation methods and general solution, errors, incomplete in the master track, harassment of coupling can be broadly divided into conduction, radiation and induction three ways:
1. transmission coupling
Features: disturbance sources and sensitive equipment are directly connected to the conductor.
Classification: total impedance and total coupling (actually two, subdivided into this)
1, the total impedance coupled
Features: disturbance sources and sensitive equipment are directly connected to the conductor.
Calculation method: General methods of analysis used circuit.
General resolution: 1, circuit decoupling, make public resistance to 0; 2, filtering, noise in the traverse up.
2. total coupling
Features: disturbance sources and sensitive equipment and impedance between total.
Calculation method: calculation of the source to the ground formation of potential distribution.
General resolution: 1, good grounding; 2, filtering, noise in the traverse up.
2. radiation coupling
Features: the induction electromagnetic field through space.
Category: differential mode radiation and common-mode radiation
1, differential-mode radiation
Characteristics: with signal phase instead of harassment. With the signal line non-vertical electric or non-existence of a parallel magnetic field that is.
Calculation method: min balance class conductors and non-equilibrium class traverse two cases for analysis.
General resolution: 1 reduce the subject field of the loop area, harassment in circuit design efforts; 2 shield
2, common mode radiation
Features: identical with signal phase. With the signal line non-vertical electric or non-existence of a parallel magnetic field that is.
Calculation method: size and circuit is the angle between the plane and electric field orientation, loop area, etc.
General resolution: 1 reduce the subject field of the loop area, harassment in circuit design efforts; 2 shield
Third, the inductive coupling
Characteristics: short distance power conductors of harassment.
Classification: capacitive coupling and inductive coupling
1, capacitive coupling
Features: disturbance sources and sensitive equipment is close, high frequency is obvious
Calculation method: static equation to determine the available Markov capacitive coupling coefficient.
General resolution: position 1 adjustments; 2 shielded wires; 3 reduce disturbed circuit impedance
2, inductive coupling
Characteristics: low-frequency is obvious
Calculation method: use polacek formula to calculate inductive coupling coefficient
General resolution: circuit design; use twisted pair. EMI coupling mode is complex, you should analyze specific problems. In principle, cannot be made in the above categories and strategies.