Inductive coupling

In electronics, change in current flow through one device induces current flow in the other device. The two devices may be physically contained in a single unit, as in the primary and secondary sides of a transformer, or may be separated as in the antennas on a transmitter and a receiver. Coupling may be intentional or unintentional. Unintentional coupling is called cross-talk, and is a form of interference. Inductive coupling favors low frequency energy sources. High frequency energy sources generally use capacitive coupling.

An inductively coupled transponder comprises an electronic data carrying device, usually a single microchip, and a large coil that functions as an antenna. Inductively coupled transponders are almost always operated passively.

Implementations

Devices that use inductive coupling

• Transformer for AC power coupling and inductive charging
• Graphics tablet
• Radio Frequency Identification
• Inductive Modems

A variety of inductive charging products charge batteries using inductive coupling, such as WiTricity and WREL.

Low frequency induction

Low frequency induction is an unwanted form of inductive coupling, which can occur when a metallic pipeline is installed parallel to a high-voltage power line. The pipeline, which is a conductor, and is insulated from the earth by its protective coating, can develop voltages which are hazardous to personnel operating valves or otherwise contacting the pipeline.