What Is an Inductive Coupler?

An inductive coupler is a device used to couple, or join, two voltage or signal-carrying conductors via a process of electromagnetic induction with no physical contact between the two. Electromagnetic inductance is a phenomenon that sees a sympathetic voltage induced, or created, in a dormant conductor by the electromagnetic field produced by a second voltage-carrying conductor placed in close proximity to it. This phenomenon may be harnessed intentionally in devices such as the inductive coupler or may occur unintentionally as undesirable cross-talk or interference. Depending on the application specifics, an inductive couple may have both coils or conductors located separately or within one sealed device. Inductive couplers are extensively used in data and audio signal transfer applications, as well as in telephones designated for use by persons using hearing aids.

Electromagnetic inductance is a fascinating phenomenon where a voltage appears almost magically in a previously dead conductor with no physical contact to any power source. Sadly, the magic turns out to be no more than the electromagnetic influence that a voltage-carrying conductor exercises on the dormant conductor. When the live, or primary, conductor, or coil as is usually the case, is brought close to the dormant, or secondary, conductor on the same axial plane, the electromagnetic field that surrounds it induces a like voltage in the dormant sibling. One of the most commonly seen examples of this phenomenon are the many transformers used in day-to-day activities, including mobile phone chargers, power supplies for toys and appliances, and even the home welding machine.

One of the many devices that makes use of this phenomenon is the inductive coupler. These devices allow the transfer of an electric voltage from one source to another without any physical contact between the two. The resultant induced voltage may be used as a power source or as a data or audio signal carrier. This produces a clean transfer without any of the usual problems associated with contaminated or damaged physical connectors. Electromagnetic inductance may not always, however, be desirable and can result in disruptive interference in communications and audio devices known as cross-talk.

Some inductive coupler types have both the primary and secondary conductors co-located within a sealed enclosure. Others feature a stand-alone, standardized primary designed to be used with any device featuring a compatible secondary conductor. This is of particular value in telecommunications devices such as telephones designed for use by those using hearing aids. The inductive coupler is also frequently used in high-fidelity data and audio transfer applications such as graphic tablets and radio antennas.