Microchips in RFID tag can be read-write, read-only or “write once, read many” (WORM). With read-write chips, you can add information to the tag or write over existing information when the tag is within range of a reader. Read-write tags usually have a serial number that can’t be written over. Additional blocks of data can be used to store additional information about the items the tag is attached to (these can usually be locked to prevent overwriting of data). Read-only microchips have information stored on them during the manufacturing process. The information on such chips can never be changed. WORM tags can have a serial number written to them once, and that information cannot be overwritten later. Microchips in RFID tags can be read-write, read-only or “write once, read many” (WORM). With read-write chips, you can add information to the tag or write over existing information when the tag is within range of a reader. Read-write tags usually have a serial number that can’t be written over. Additional blocks of data can be used to store additional information about the items the tag is attached to (these can usually be locked to prevent overwriting of data). Read-only microchips have information stored on them during the manufacturing process. The information on such chips can never be changed. WORM tags can have a serial number written to them once, and that information cannot be overwritten later.

Just as your radio tunes in to different frequencies 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-frequency (around 125 KHz), high-frequency (13.56 MHz) and ultra-high-frequency or UHF (860-960 MHz). Microwave (2.45 GHz) is also used in some applications. Radio waves behave differently at different frequencies, so you have to choose the right frequency for the right application.

ISO 14443 has two variants, Type A and Type B. ISO 14443A was accepted by the ISO committee in 1997. It is the first ISO standard for 13.56 MHz frequency contactless card which was developed by Mikron Austria and acquired by Phillips in 1996. Currently, ISO 14443A is the most widely used contactless standard in the world, mainly in transport applications.
ISO 14443B was approved by the ISO committee in 1998. ISO 14443B has a number of advantages over ISO 14443A:
1. Unlike ISO 14443A uses 100% modulation depth, it means that the reader stops emitting the field for defined periods of time. The modulation depth for ISO 14443B is only 10% which preserves the continuity of the clock.
2. No patents on communication coding.
3. Communication speeds of up to 847 KHz.
4. Adopted as a national standard by many countries, such as US, China, Japan, etc.
A third variant of the ISO 14443 standard, Type C, was developed by Sony, however, it was abandoned by the ISO/IEC committee and now is renamed as Felica.
*Securitag Assembly Group (SAG) is able to provide ISO 14443 proximity coupling smart cards and tags with the following RFID technologies:
ISO 14443A:  Mifare 1K, Mifare 4K, Mifare Ultralight, Mifare DESFire, SLE66R35
ISO 14443B: AT88RF020, SR176, SRIX512, SRIX4K
Felica (ISO 14443C): RC-S919

One of the main concerns with RFID tags is that their contents can be read by anyone with an appropriately equipped scanner – even after you take it out of the store.
One technology that has been suggested is a zombie RFID tag, a tag that can be temporarily deactivated when it leaves the store. The process would work like this: you bring your purchase up to the register, the RFID scanner reads the item, you pay for it and as you leave the store, you pass a special device that sends a signal to the RFID tag to “die.” That is, it is no longer readable.
The “zombie” element comes in when you bring an item back to the store. A special device especially made for that kind of tag “re-animates” the RFID tag, allowing the item to reenter the supply chain.

Some vendors have been combining RFID tags with sensors of different kinds. This would allow the tag to report not simply the same information over and over, but identifying information along with current data picked up by the sensor. For example, an RFID tag attached to a leg of lamb could report on the temperature readings of the past 24 hours, to ensure that the meat was properly kept cool.
Over time, the proportion of “scan-it-yourself” aisles in retail stores will increase. Eventually, we may wind up with stores that have mostly “scan-it-yourself” aisles and only a few checkout stations for people who are disabled or unwilling.

Civil liberties groups (among others) have become increasingly concerned about the use of RFIDs to track the movements of individuals. For example, passports will soon be required to contain some sort of RFID device to speed border crossings. Scanners placed throughout an airport, for example, could track the location of every passport over time, from the moment you left the parking lot to the moment you got on your plane.
In June, the Japanese government passed a draft RFID Privacy Guideline that stated the following:

  • Indication that RFID tags exist
  • Consumers right of choice regarding reading tags
  • Sharing information about social benefits of RFID, etc.
  • Issues on linking information on tags and databases that store privacy information.
  • Restrictions of information gathering and uses when private information is stored on tags
  • Assuring accuracy of information when private information is stored on tags
  • Information administrators should be encouraged
  • Information sharing and explanation for consumers

There are also concerns about the fact that, even after you leave the store, any RFID devices in the things you buy are still active. This means that a thief could walk past you in the mall and know exactly what you have in your bags, marking you as a potential victim. A thief could even circle your house with an RFID scanner and pull up data on what you have in your house before he robs it.
Military hardware and even clothing make use of RFID tags to help track each item through the supply chain. Some analysts are concerned that, if there are particular items associated with high-level officers, roadside bombs could be set to go off when triggered by an RFID scan of cars going by.
There was a recent report revealing clandestine tests at a Wal-Mart store where RFID tags were inserted in packages of lipstick, with scanners hidden on nearby shelves. When a customer picked up a lipstick and put it in her cart, the movement of the tag was registered by the scanners, which triggered surveillance cameras. This allowed researchers 750 miles away to watch those consumers as they walked through the store, looking for related items.

Unfortunately, not very often in the systems to which consumers are likely to be exposed. Anyone with an appropriately equipped scanner and close access to the RFID device can activate it and read its contents. Obviously, some concerns are greater than others. If someone walks by your bag of books from the bookstore with a 13.56 Mhz “sniffer” with an RF field that will activate the RFID devices in the books you bought, that person can get a complete list of what you just bought. That’s certainly an invasion of your privacy, but it could be worse. Another scenario involves a military situation in which the other side scans vehicles going by, looking for tags that are associated with items that only high-ranking officers can have, and targeting accordingly.

Companies are more concerned with the increasing use of RFID devices in company badges. An appropriate RF field will cause the RFID chip in the badge to “spill the beans” to whomever activates it. This information can then be stored and replayed to company scanners, allowing the thief access – and your badge is the one that is “credited” with the access.
The smallest tags that will likely be used for consumer items don’t have enough computing power to do data encryption to protect your privacy. The most they can do is PIN-style or password-based protection.

RFID tags come in a wide variety of shapes and sizes; they may be encased in a variety of materials:

  • Animal tracking tags, inserted beneath the skin, can be rice-sized.
  • Tags can be screw-shaped to identify trees or wooden items.
  • Credit-card shaped for use in access applications.
  • The anti-theft hard plastic tags attached to merchandise in stores are also RFID tags.
  • Heavy-duty 120 by 100 by 50 millimeter rectangular transponders are used to track shipping containers, or heavy machinery, trucks, and railroad cars.

RFID devices have been used for years to identify dogs, for a means of permanent identification. Dog owners had long used tattoos, permanent ink markings, typically on the ears. However, these can fade with age and it may be difficult to get the animal to sit still while you examine him for markings.
Many musical instruments are stolen every year. For example, custom-built or vintage guitars are worth as much as $50,000 each. Snagg, a California company specializing in RFID microchips for instruments, has embedded tiny chips in 30,000 Fender guitars already. The database of RFID chip IDs is made available to law enforcement officials, dealers, repair shops and luthiers.

RFID devices that are intended to be implanted inside a living body (like an animal or human being) have special requirements. They need to be encased in a special kind of casing that will not irritate or react with the living tissues that they are inserted into. The casing must also be transparent to the scanning radio-frequency beam that activates the chip. Some RFID vendors have created biocompatible glass for use in these applications.
One potential problem with being placed within a living organism is that the tiny RFID device may move around under the skin. This can be avoided by using special materials that actually let the surrounding tissue grow up to the casing and bond with it.
Because the radio-frequency waves that activate the microchip containing the identification number are only useful within a few feet (or less), the RFID chip is typically inserted very close to the surface of the skin.
The placement of the device is usually done with a hyperdermic-type needle. This method of insertion also dictates the shape and size of the device; implantable RFID devices are typically the size and diameter of a grain of rice. For dogs, the device is usually implanted between the shoulder blades.
RFID tags have been placed inside cows; some discussion of having all cows implanted with RFID devices has resulted from the recent scare with mad cow disease. Dog owners have used RFID tags to identify their pets rather than tattoos (the more traditional method).
RFID tags, like the VeriChip tag, can also be implanted inside human beings

A Radio-Frequency Identification system has three parts:

  • A scanning antenna
  • A transceiver with a decoder to interpret the data
  • A transponder – the RFID tag – that has been programmed with information.

The scanning antenna puts out radio-frequency signals in a relatively short range. The RF radiation does two things:

  • It provides a means of communicating with the transponder (the RFID tag) AND
  • It provides the RFID tag with the energy to communicate.

This is an absolutely key part of the technology; RFID tags do not need to contain batteries, and can therefore remain usable for very long periods of time (maybe decades).
The scanning antennas can be permanently affixed to a surface; handheld antennas are also available. They can take whatever shape you need; for example, you could build them into a door frame to accept data from persons or objects passing through.
When an RFID tag passes through the field of the scanning antenna, it detects the activation signal from the antenna. That “wakes up” the RFID chip, and it transmits the information on its microchip to be picked up by the scanning antenna.
In addition, the RFID tag may be of one of two types. Active RFID tags have their own power source; the advantage of these tags is that the reader can be much farther away and still get the signal. Even though some of these devices are built to have up to a 10 year life span, they have limited life spans. Passive RFID tags, however, do not require batteries, and can be much smaller and have a virtually unlimited life span.
RFID tags can be read in a wide variety of circumstances, where Barcodes or other optically read technologies are useless.

  • The tag need not be on the surface of the object (and is therefore not subject to wear)
  • The read time is typically less than 100 milliseconds
  • Large numbers of tags can be read at once rather than item by item.

In essence, that’s how RFID works.

A significant advantage of RFID devices over the others mentioned above is that the RFID device does not need to be positioned precisely relative to the scanner. We’re all familiar with the difficulty that store checkout clerks sometimes have in making sure that a barcode can be read. And obviously, credit cards and ATM cards must be swiped through a special reader.
In contrast, RFID devices will work within a few feet (up to 20 feet for high-frequency devices) of the scanner. For example, you could just put all of your groceries or purchases in a bag, and set the bag on the scanner. It would be able to query all of the RFID devices and total your purchase immediately.
RFID technology has been available for more than fifty years. It has only been recently that the ability to manufacture the RFID devices has fallen to the point where they can be used as a “throwaway” inventory or control device. Alien Technologies recently sold 500 million RFID tags to Gillette at a cost of about ten cents per tag.
One reason that it has taken so long for RFID to come into common use is the lack of standards in the industry. Most companies invested in RFID technology only use the tags to track items within their control; many of the benefits of RFID come when items are tracked from company to company or from country to country.

RFID stands for Radio-Frequency Identification. The acronym refers to small electronic devices that consist of a small chip and an antenna. The chip typically is capable of carrying 2,000 bytes of data or less.
The RFID device serves the same purpose as a bar code or a magnetic strip on the back of a credit card or ATM card; it provides a unique identifier for that object. And, just as a bar code or magnetic strip must be scanned to get the information, the RFID device must be scanned to retrieve the identifying information.