RFID

There are three types of radio identification tags, known as passive, semi-passive, or active. You may find that the semi-passive tags are also known as semi-active, whatever they are called, and they generally refer to the same thing. Depending on exactly what you are doing, you will need or desire a specific type of tag. The cost and size of each tag will also determine which type is most efficient for you.

First, there are passive tags. This type of radio frequency identification tag has no internal power supply. The way that the tag responds is by a very small electrical current that is provided by the antenna of the incoming radio frequency signal. This small current provides just enough power for the integrated circuit in the tag to transmit a response. This is done by backscattering the carrier signal from the reader, which means that the antenna is designed to collect power from the incoming signal as well as transmit the outbound backscatter signal. The benefit of a passive tag is that it can be quite small, since it does not have its own power supply. There are commercially produced devices that can be placed under the skin and measure as little as .15mm by .15mm and are even thinner than a sheet of paper! When an antenna is added into the mix the passive tag will typically be as small as a postage stamp and as big as a post card. Passive tags can be read from about 2mm to a few meters away, depending on the radio frequency that is being used. Most of the RFID tags that are used are of the passive nature because they have an unlimited life span and are the least expensive type of tag available.

Next, there are semi passive radio frequency identification tags that are quite similar to the passive tag, although this type of tag has a small battery. The battery in a semi passive tag allows the tag IC to be powered at all times. Because the IC is powered at all times, the tag needn't have the ability to collect power from incoming signals, making them much faster to respond as well as stronger when reading ratio when you compare them to the relatively uncomplicated passive tag. Because the tag uses a battery, its life is limited to the battery life.

Active tags are the third type of tags and are commonly known as beacons because they are capable of broadcasting their own signal. This type of tag has their own internal power source that it used to power any IC's as well as to generate an outgoing signal. Active tags typically have a wider rage as well as a longer memory than passive tags as well as the ability to store information that is sent by the transceiver. Many active tags attempt to conserve power by operating at timed intervals. The smallest active tag is about the size of a quarter and has a decent range and can be used for about five years before the battery life would end.

There are several other ways that radio frequency identification tags can be classified. The type of microchip within the tag will determine if it will be a read only, a read and write tag, or a write once read many. The information that is stored on a read/write tag can be edited, added to, or rewritten when the tag is within the range of the reader. The information stored on a read and write tag can be read but cannot be edited in any way, just as the write once and ready many tags. The read/write tags are much more expensive than the read only tags, so most opt for the read only tags. Radio frequency identification tags hold a whole range of information and are sold in a number of formats much like the compact discs that we buy for our computers that are sold in a number of formats to give us the space that we need. If you need to transmit just a small amount of information you'll opt for less storage space than if you need to obtain and transmit a small amount of information.

While the radio frequency identification tag has been around for quite awhile, it has always been second to barcodes and such because of its expense. But, as technology plows along and prices come down, more and more retailers and large corporations are going to RFID tags because they are not much more expensive and are capable of a lot more than most barcodes have ever been capable of. When companies buy in bulk they obviously get a better rate than if just a few tags are purchased, but RFID tags generally cost from five to 50 cents per tag. When you consider how well they work, most companies are willing to consider the cost, which is not all that much more than barcode systems. In fact, the most successful retailer in the United States, Wal-Mart, now requires all of its suppliers to use RFID tags when they ship items to the stores so that items can be tracked as well as for security purposes.

As radio frequency identification tags become more refined and technologically advanced, there is no doubt that they will continue to be used for a variety of things. From tracking on the railroads, to implants in humans and animals, there is no limit to what we can do and what sort of information we can obtain with the use of radio frequency identification tags. The science and system behind the tags started out as a relatively simple process, but as we've gone along the tags have gotten smaller and more intricate, giving us the incentive to find new and better uses for the technology all of the time. While the distances in which the tags can be read is somewhat limited at this point in time, there is evidence that in time we will be able to read the tags from much farther away, increasing the uses yet again. The future of the radio frequency identification tag is undoubtedly bright.