In an RFID solution, RFID tags are attached to all items or things that are to be tracked. RFID Tags consist of a tag-chip, that is connected to an antenna which is built into many different formats. Examples include: apparel hang tags, logistic labels for card-board boxes, security tags, and a variety of industrial asset hard-tags. The tag-chip contains memory which stores the product’s electronic product code (EPC) and other variable information. This memory can be written (coded) and read by RFID readers (interrogators) so that the tags can be tracked anywhere. RFID readers are network connected hardware devices (fixed or mobile) with an antenna that send power as well as data and commands to RFID tags. The RFID reader acts like an access point for RFID tagged items so that the tags’ data can be made available to business application software or ERP software solutions.
RFID tags are built up of an integrated circuit (called an IC or chip) attached to an antenna that has been printed, etched, stamped or vapor-deposited onto a mount or layer which is often a paper substrate or Poly Ethylene Therephtalate (PET). The tag chip and antenna combination, called a dry- or wet inlay, is then converted or sandwiched between a printed label and its adhesive backing to form a smart flexible label or inserted into a more durable structure to form a hard tag.
The tag’s chip or integrated circuit (IC) determines the performance, memory and extended features to the tag. The chip is pre-programmed with a tag identifier (TID), a unique serial number assigned by the chip manufacturer, and includes a memory bank to store the items’ unique tracking identifier (called an electronic product code or EPC). There are several different manufacturers of tag chips like Impinj, NXP and Alien. Each of these supplier offer a variety of tag chips with different functionality aiming on specific use cases.
Tag antennas collect energy broadcasted by the RFID Readers and channel it to the chip to “turn it on”. Generally, the larger the tag antenna’s surface, the more energy it will be able to collect and channel toward the tag chip, and the longer the read range of the tag will be. There is not a “perfect antenna” that is best for all applications. The applications (or the to be tagged items) and the region of use define the antenna specifications. Some tags are optimized for use in a particular frequency band, while other tags might be tuned for best performance when attached to materials that may not normally work well for wireless communication (certain liquids and metals, for example). Antennas can be made from a variety of conductive materials; they can be printed, etched, stamped with conductive ink, or even vapor deposited onto labels.
RFID tags that have only a single antenna are not as reliable as tags with multiple antennas. With a single antenna, a tag’s orientation can result in so-called “dead zones”, or areas on the tag where energy from incoming signals may not be sufficient to power on the chip and enabling it to communicate with the reader. A tag with dual antennas is more likely to eliminate “dead zones” thus increasing its readability. A dual-antenna tag can be built using special tag chips like the Impinj Monza4D with omni-directional antenna support.
Electronic Product Code (EPC)
The electronic product code (EPC) stored in the tag chip’s memory is often “written to” the tag by a RFID printer and takes the form of at the minimum 96-bit string of data. The above picture explains what the main parts of the EPC code look like. The first eight bits is called the header which identifies the version of the protocol. The second 28 bits identify the organization that manages the data for this tag; the organization number is assigned by the EPCglobal organization. The third 24 bits represent the object class, identifying the kind of product. The fifth 36 bits are the unique serial number for a particular tag. These last two fields are set by the organization that issued the tag. The total EPC number can be used as a key into a global database to uniquely identify a particular product.
An RFID reader, also known as an interrogator, is a device that provides the connection between the tag data and the enterprise system software that needs the information also called the front-end. The reader communicates with tags that are within its field of operation, performing any number of tasks including simple continuous inventorying, filtering (searching for tags that meet certain criteria), writing (or encoding) to selected tags, etc.
The reader uses an attached antenna to capture data from tags. It then passes the data to a computer for processing. Just like RFID tags, there are many different sizes and types of RFID readers. Readers can be affixed in a stationary position in a store or factory, or integrated into a mobile device such as a portable, handheld scanner. Readers can also be embedded in electronic equipment or devices, and in vehicles.
An RFID reader, also known as an interrogator, is a piece of hardware that provides the connection between the tag data and the enterprise system software that needs the information also called the front-end. Readers communicate with tags that are within the read range, performing any number of tasks including simple continuous inventorying, filtering (searching for tags that meet certain criteria), writing (or encoding) to selected tags, etc.
The reader uses an attached antenna to “turn-on” tags and capture data from tags. It then passes the data to a computer for processing. Just like RFID tags, there are many different sizes, formats and types of RFID readers. RFID readers can be fixed mounted in a stationary position in a portal, store or factory, or integrated into a mobile device such as a portable, handheld scanner. RFID readers can also be embedded in electronic equipment or devices and in vehicles.
RFID readers and reader antennas work in combination to read tags and collect tag data. Reader antennas convert the electrical current from the RFID reader into electromagnetic waves that are radiated into space. When a tag antenna receives electromagnetic waves these are converted back to electrical current this way turning-on the chip. Just like tag antennas, there is a large variety of reader antennas available and optimal antenna selection varies according to the solution’s specific application and environment.
Most common antenna types are linear- and circular-polarized antennas. Antennas radiating linear electric fields have relatively long ranges, and high levels of power enabling their signals to penetrate through different materials to read tags. Linear antennas are sensitive to the tags orientation; depending on the tag angle or placement, linear antennas can have a difficult time reading tags. Antennas that radiate circular fields are less sensitive to orientation, but are not able to deliver as much power as linear antennas. Besides orientation issues the choice of antenna type is also determined by the distance between the RFID reader and the tags that it needs to read. This read distance is called read range. Reader antennas operate in either a “near-field” (short range) or “far-field” (long range).
In near-field applications the read range is less than 30 cm and the antenna uses magnetic coupling to transfer power to the tag. In near-field systems, the readability of the tags is hardly affected by the presence of dielectrics such as water and metal in the field.
In far-field applications the distance between the tag and reader is more than 30 cm and can be up to several tens of meters. Far-field antennas utilize electromagnetic coupling and dielectrics can heavily influence the communication between the reader and tags.
Reader Control and Application Software
Reader control and application software, also known as middleware, is used to connect RFID readers with the applications they support. The middleware sends control commands to the reader and receives tag data from the reader. Middle ware is used to communicate with application software of legacy systems. Some RFID reader manufacturers have developed or are developing software to enable easier implementation and roll-outs of their hardware.
Creating an RFID Solution
Deploying an RFID solution almost always requires multiple parties and many different components. Installing a system requires basic hardware-including tags, readers, and reader antennas as well as reader control and application software. Of course a solution or system also requires solution providers or system integrators to put it all together. When all of these components and parties come together, an infinite number of creative applications are possible. RFID system applications can help improve the quality and efficiency of business operations, and customer experience in a variety of industries and applications.