How Do Radio Tagged Cards Work?

December 1, 2008

Radio Frequency Identification (RFID) systems have three components: a small silicon microchip attached to an antenna; a reader and a computer database.

The RFID tags themselves can be as small as half a millimeter square, the size of a tiny seed. Some are thin enough to be embedded in paper. Most tags today are passive – meaning they don’t have an independent power source.

Instead, they are powered up when scanned by a reader. Once powered up, the tag transmits information by radio wave to the reader. The reader, in turn, transmits the information it receives from the tag to a computer database, where the information is stored an analyzed.

Readers can access the low-powered RFID tags from only a few inches away. Ultra high frequency chips can be read from up to 50 meters away. The effective reading distance depends on many factors, but the tags can be read without being taken out of a handbag or a wallet by any nearby reader.

As late as June, some RFID-enabled credit cards transmitted unencrypted customer names to nearby readers. 

RFID tags already are quite common.  In 2005, 1.3 billion RFID tags were sold.  Just a year later, sales increased to 3.1 billion. The industry estimates sales of RFID tags at more than In 1 trillion a year by 2015.  The price is expected to drop from about 30 cents to 3 cents over the next several years.

Today, they are found in:

  • Proximity cards, which have replaced many metal door keys and allow entrance to offices and buildings.
  • Automated toll payment devices, such as EZ Pass and SunPass.
  • Tens of millions of pets worldwide. The tags have been surgically embedded to make it easy for owners to identify a lost pet.
  • Warehouse inventory systems
  • Car keys, credit cards, driver licenses, U.S. Passports, identification cards, library books and some pharmaceuticals.

The most expensive RFID tags are capable of encrypting information. The least expensive tags lack the computer power necessary to perform even the most basic encryption, storing only an identifier.

The identifiers, however, when coupled with a database can link together an immense amount of information. In the case of a product, it can show where it was manufactured, shipping information, when and where it was sold.

In 2003, Alexandra Hospital in Singapore began a trial tracking system in its accident and emergency department in the wake of the Severe Acute Respiratory Syndrome (SARS).

Upon entering the hospital, all patients, visitors and staff are issued a RFID-embedded card. The card is red by sensors installed in the ceiling, which record exactly when a person enters and leaves the department.

Hospital officials said the system would allow them to use a database to determine who could have been in contact with whom in the event of an outbreak.

Civil liberties advocates say that the ability to track people, products, vehicles and even currency would create an Orwellian world where law enforcement and retailers could read the contents of a handbag or wallet without a person’s knowledge, simply by installing RFID readers nearby.