There are 3 main RFID technologies:
- LF (most popular currently), uses 125kHz band
- HF, uses 13,56MHz with better safety algorithms
- UHF, uses 868MHz, this technology has a great potential for industrial applications, warehouse management, document tracking, supply chain management etc.
LF RFID is the oldest and simplest technology used. Many applications use this technology for example, for key locks, gate openers, password input devices, attendance management systems, elevator security systems, burglar alarm systems or pet registration applications. Tags can be manufactured in different sizes, starting with small glass tags used for pet marking (size is around 3-5mm in diameter), following by key fobs, wristbands used in attendance systems or cashless payment in closed environments such wellness hotels, schools, fun parks etc.
The most popular tag size is still the ISO credit card, which is very handy and can be easily printed with company logo, cardholder's name etc. The reading distance for 125kHz RFID technology is few centimeters (approx. up to 15-20cm). The reading distance highly depends on tag's/reader's antenna size; the smaller the antenna, the shorter the reading distance. Also very important is the mutual position of tag and reader – the best result can be achieved if reader's antenna is exactly in parallel with tag's antenna.
125kHz RFID technology typically uses EM Marin's EM4102 or compatible chips from other manufacturers with fixed serial number written into chip's ROM during the manufacturing process. Thus the only possible function of EM4102 chips is reading their unique identifier with the reader; its functionality is very similar to the barcode scanner.
From the interface point of view, some different RFID reader versions are available: USB HID interface is used as standard PC keyboard replacement mainly for password entry or serial number entry, RS232 or virtual COM port readers via USB are often used with specialized software like warehouse management or attendance systems. There are also special RFID readers available with programmable functionality; they can run a code inside the reader and make some operations with the information read from the tag.
If you need to clone your 125kHz RFID tag, there is a T5577 chip, which can store EM4102's identifier and act as a standard EM4102 chip to the reader.
HF (13,56MHz) RFID technology also known as Mifare or ISO14443 and its versions like Ultralight, Desfire, etc. is widely used for cashless payment systems e.g. in transportation (bus tickets, train tickets, electronic wallet etc.). Because this technology uses high level of security algorithms and Mifare chips have embedded memory, they are very useful for cashless payment applications like debit or credit cards.
New bank cards with wireless chip embedded uses 13,56MHz technology as well.
Tags can be manufactured as wristbands, key fobs, inlays and ISO cards of course. Reading distance for 13,56MHz is few centimeters, best readers can achieve around 10-12cm.
UHF (868MHz for Europe or 915MHz for North America) is the youngest RFID technology and wide spreading in industrial applications like warehouse management or parcel tracking. Because reading distances can reach up to few meters (4-5m), tag placement is more flexible comparing to LF or HF technology.
Also tag design can be very flexible and we can see tags from small buttons or coins, through differently shaped inlays, plastic labels, wristbands, credit cards, etc. UHF technology was not designed for human/pet tracking purposes as reading distance for tags placed close to human body falls down significantly due to high absorption of radio wave energy by human body.