Proximity readers continuously transmit a low-level fixed radio frequency (RF) signal that provides energy to the card. When the card is held at a certain distance from the reader, the RF signal is absorbed by a small coil inside the card that powers up the card’s microchip which contains a unique identification code. Once powered, the card transmits the code to the reader. The whole process is completed in microseconds.
Proximity reader for high-security access control systems