Wiegand wire

Wiegand wire

[′vē·gänt ‚wīr]
(electricity)
A work-hardened wire whose magnetic permeability is much greater near its surface than at its center.

Wiegand wire

An iron-alloy wire that has unique magnetic properties. Invented by John Wiegand in 1972 and used in sensor applications, the Wiegand wire's outer layer can be magnetized without affecting the inner core. When an external magnetic field is applied, the core switches polarity to that direction and emits a large pulse. As the field is intensified, a smaller pulse is emitted.

Magnetic Key Codes
Used in keycard door locks, the plastic keycards have two embedded rows of Wiegand wires in a specific polarity pattern that represents a 26-bit ID number. When run through a magnetic field strong enough to switch the polarities of the inner cores, pulses are generated. The pulses energize a coil that creates a signal detected by a sensor. Although Wiegand cards are not as predominant as they were in the past, the 26-bit ID format has been carried over to many access control systems. See access control.
References in periodicals archive ?
Wiegand Wire technology was developed in the 1950s and is now manufactured by HID Corporation (formerly Sensor Engineering).
While it is the most expensive card technology available due to the complex manufacturing process, Wiegand Wire offers better security, making it appropriate for use at airports, government agencies, power stations, and hospitals.
The Wiegand wire is a specially treated ferromagnetic wire.
When the card is moved through a set of magnetic fields, each Wiegand wire sends an electrical pulse-interpreted as a one or zero for each track-to a coil in the reader.
Since the encoding of the Wiegand wires in the card is tightly controlled by Sensor, which still holds the patent, two identical badges are never made.