RFID card
An RFID card is a contactless smart card with radio data and energy transmission. The RFID card consists of two thin plastic cards in which the RFID tag - a chip containing the processor, memory and transponder - and the transmitting and receiving antenna are embedded. They are therefore also referred to as transponder cards.
The memory size depends mainly on the application and can range from 8 bytes (B) to 8 KB. Some RFID cards even have their own memory organization. The transponder is a transmitting/receiving device that, like the antenna, is tuned to the radio frequency. RFID systems use the license-free ISM bands at 125 kHz and 13.56 MHz for radio transmission.
There are RFID cards with error correction, password protection, encryption and write protection. There are transponder cards that can only be read, others that can be written and read.
RFID cards can contain an active tag, a semi- passive tag and a passive tag. The active tags have a transmitter and a rechargeable battery, the passive ones take the required energy from the carrier signal of the RFID reader. This is a wireless energy transmission via the radio link. RFID transmission is aimed at close range and, depending on the RFID frequency, can bridge distances between a few centimeters and a few meters, with the active RFID cards having a much wider range than the passive ones. The cards operate without wear, are insensitive to dirt and moisture, and are merely held near the RFID reader during checks; they do not need to be taken out of the pocket during access checks.
RFID cards are used for access control, employee ID cards, public transport, identification, ticketing, ski passes, university payment transactions and toll systems, to name just a few examples.