Coupling (electronics)

In electronics and telecommunication, coupling is the desirable or undesirable transfer of energy from one medium, such as a metallic wire or an optical fiber, to another medium, including fortuitous transfer.

Coupling is also the transfer of electrical energy from one circuit segment to another. For example, energy is transferred from a power source to an electrical load by means of conductive coupling, which may be either resistive or hard-wire.  An AC potential may be transferred from one circuit segment to another having a DC potential by use of a capacitor.  Electrical energy may be transferred from one circuit segment to another segment with different impedance by use of a transformer. This is known as impedance matching. These are examples of electrostatic and electrodynamic inductive coupling.

Types of coupling

Electrical conduction:

• hard-wire
• resistive
• natural conductor

Electromagnetic induction:

• electrodynamic -- commonly called inductive coupling, also magnetic coupling
• electrostatic -- commonly called capacitive coupling
• evanescent wave coupling

Electromagnetic radiation:

• radio -- wireless telecommunications
• electromagnetic interference (EMI) -- Sometimes called radio frequency interference (RFI), is unwanted coupling. Electromagnetic compatibility (EMC) requires techniques to avoid such unwanted coupling, such as electromagnetic shielding.
• Microwave power transmission

Other kinds of energy coupling:

• acoustic

See also

• antenna noise temperature
• coupling loss
• directional coupler
• equilibrium length
• fiber-optic coupling
• loading coil
• shield
• list of electronics topics
• AC Coupling
• impedance matching
• impedance bridging
• decoupling

References

 This article incorporates public domain material from the General Services Administration document "Federal Standard 1037C" (in support of MIL-STD-188).