Frequently Asked Questions (FAQs)

This section contains the top 10 most frequently asked questions about RFID technology:

Radio frequency identification, or RFID, is a generic term for technologies that use radio waves to automatically identify people or objects. There are several methods of identification, but the most common is to store a serial number that identifies a person or object, and perhaps other information, on a microchip that is attached to an antenna (the chip and the antenna together are called an RFID transponder or an RFID tag). The antenna enables the chip to transmit the identification information to a reader. The reader converts the radio waves reflected back from the RFID tag into digital information that can then be passed on to computers that can make use of it

An RFID system consists of a tag, which is made up of a microchip with an antenna, and an interrogator or reader with an antenna. The reader sends out electromagnetic waves. The tag antenna is tuned to receive these waves. A passive RFID tag draws power from field created by the reader and uses it to power the microchip’s circuits. The chip then modulates the waves that the tag sends back to the reader and the reader converts the new waves into digital data.

Just as your radio tunes in to different frequency to hear different channels, RFID tags and readers have to be tuned to the same frequency to communicate. RFID systems use many different frequencies, but generally the most common are low- (around 125 KHz), high- (13.56 MHz) and ultra-high frequency, or UHF (850-900 MHz). Microwave (2.45 GHz) is also used in some applications. Radio waves behave differently at different frequency, so you have to choose the right frequency for the right application.

Different frequencies have different characteristics that make them more useful for different applications. For instance, low-frequency tags are cheaper than ultra high frequency (UHF) tags, use less power and are better able to penetrate non-metallic substances. They are ideal for scanning objects with high-water content, such as fruit, at close range. UHF frequencies typically offer better range and can transfer data faster. But they use more power and are less likely to pass through materials. And because they tend to be more “directed,” they require a clear path between the tag and reader. UHF tags might be better for scanning boxes of goods as they pass through a bay door into a warehouse. It is probably best to work with a consultant, integrator or vendor that can help you choose the right frequency for your application.

Active RFID tags have a battery, which is used to run the microchip’s circuitry and to broadcast a signal to a reader (the way a cell phone transmits signals to a base station). Passive tags have no battery. Instead, they draw power from the reader, which sends out electromagnetic waves that induce a current in the tag’s antenna. Semi-passive tags use a battery to run the chip’s circuitry, but communicate by drawing power from the reader. Active and semi-passive tags are useful for tracking high-value goods that need to be scanned over long ranges, such as railway cars on a track, but they cost a dollar or more, making them too expensive to put on low-cost items. Companies are focusing on passive UHF tags, which cost under a 50 cents today in volumes of 1 million tags or more. Their read range isn’t as far – typically less than 20 feet vs. 100 feet or more for active tags – but they are far less expensive than active tags and can be disposed of with the product packaging.

Automatic identification, or auto ID for short, is the broad term given to a host of technologies that are used to help machines identify objects. Auto identification is often coupled with automatic data capture. That is, companies want to identify items, capture information about them and somehow get the data into a computer without having employees type it in. The aim of most auto-ID systems is to increase efficiency, reduce data entry errors, and free up staff to perform more value-added functions, such as providing customer service. There are a host of technologies that fall under the auto-ID umbrella. These include bar codes, smart cards, voice recognition, some biometric technologies (retinal scans, for instance), optical character recognition, and radio frequency identification (RFID).

The Electronic Product Code, or RFID, was developed by the Auto-ID Center as a successor to the bar code. It is a numbering scheme that will be used to identify products as they move through the global supply chain. For more on EPC technology, see Electronic Product Code FAQs.

The read range of passive tags (tags without batteries) depends on many factors: the frequency of operation, the power of the reader, interference from metal objects or other RF devices. In general, low-frequency tags are read from a foot or less. High frequency tags are read from about three feet and UHF tags are read from 10 to 20 feet. Where longer ranges are needed, such as for tracking railway cars, active tags use batteries to boost read ranges to 300 feet or more.

In open, global supply chains, passive UHF RFID is the preferable choice because of the longer read distances and faster data transfer rates between tags and readers. The RFID Standards have been developed by a broad stakeholder community over a number of years facilitated by the GS1 organisation; a global, not-for-profit standards development organisation based in Brussels, Belgium. For a comprehensive overview of the Standards, see EPC/RFID Standards.

The New Zealand RFID –Pathfinder Group was established in 2006 to provide independent advice and guidance on ‘things RFID’. For any questions or for more information on RFID, who to talk to, where to go from here, contact the Secretary.