How do these types of contactless cards differ?
Terms in the RFID industry are often used loosely, which can be confusing. There are actually only two types of cards: proximity and vicinity. Vicinity cards contain a passive high-frequency (HF) transponder and typically use the ISO 15693 air-interface protocol standard. These cards can be read at a distance of up to 3 feet (0.9 meter). They are often used for access control or inventory control.
For financial transactions, users want to ensure that tag-to-reader communication cannot be intercepted by someone with an RFID reader, so they use the ISO 14443 air-interface protocol standard, which is designed to have a short read range (only a few centimeters). That’s all that is required when you are paying at a point-of-sale terminal. These cards are called proximity cards because the transponder needs to be in close proximity to the reader. (Near Field Communication [NFC] is based on ISO 14443 and has recently incorporated the ISO 15693 air-interface protocol standard as well.)
ISO 14443 tags employ close coupling. That is, such a tag, when placed near a reader antenna, couples with it. Close coupling can be used to describe magnetic coupling or inductive coupling, but most people in the industry refer to proximity cards, rather than close coupling cards.
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—Mark Roberti, Founder and Editor, RFID Journal
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