Introduction to RFID technology
In general terms, RFID (Radio Frequency Identification) is a means of identifying a person or object using a radio frequency transmission. The technology can be used to identify, track, sort or detect a wide variety of objects. Communication takes place between a reader (interrogator) and a transponder (Silicon Chip connected to an antenna) often called a tag.
Tags can either be active (powered by battery) or passive (powered by the reader field), and come in various forms including Smart cards, Tags, Labels, watches and even embedded in mobile phones. The communication frequencies used depends to a large extent on the application, and range from 125KHz to 2.45 GHz. Regulations are imposed by most countries (grouped into 3 Regions) to control emissions and prevent interference with other Industrial, Scientific and Medical equipment (ISM).
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LF |
HF |
UHF |
Microwave |
Frequency Range |
< 135 KHz |
13.56 MHz |
860 - 930 MHz [1] |
2.45GHz |
Standards Specifications |
ISO/IEC 18000-2 |
ISO/IEC 18000-3 AutoID HF class 1 ISO 15693, ISO 14443 (A/B) |
ISO/IEC 18000-6 AutoID class 0, class 1 |
ISO/IEC 18000-4 |
Typical Read Range |
<0.5m |
~ 1m |
~4 -5 m[2] |
~ 1m |
General |
Larger Antennas resulting in higher cost tags. least susceptible to performance degradations from metals and liquids |
Less expensive than LF tags, Best suited for applications that do not require long range reading of high number of tags. This frequency has the widest application scope. |
In volume UHF tags have the potential to be cheaper than LF or HF due to recent advances in IC design. Good for reading multiple tags at long range. More affected than LF and HF by performance degradations from metals and liquids |
Similar characteristics to UHF but faster read rates. Drawback is microwaves are much more susceptible to performance degradations from metals and liquids. |
Tag power source |
Mainly passive using inductive coupling (near field) |
Mainly passive using inductive coupling (near field) |
Active and passive tags using E-Field back scatter in the far field |
Active and passive tags using E-Field back scatter in the far field |
Typical applications |
Access Control, Animal tagging, Vehicle immobilizers |
Smart cards, Access Control, Payment, ID, Item level tagging, baggage control, Biometrics, Libraries, laundries, Transport, Apparel |
Supply Chain pallet and Box tagging, Baggage Handling, electronic toll collection. |
Electronic toll collection, Real Time Location of goods. |
Notes |
Largest installed base due to mature technology. However will be overtaken by higher frequencies |
Currently the most widely available high frequency world-wide due to the adoption of smart cards in |
Different frequencies and power allocated by different countries US 4W(EIRP) 915MHz, Europe 0.5W (ERP) |
5.8 GHz more or less abandoned for RFID |
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transport. |
868 MHz, [2] |
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Multiple Tag Read Rate |
Slower |
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Faster |
Ability to read near metal or |
Better |
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Worse |
wet surfaces |
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Passive Tag Size |
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