RFID Readers and Tags Explained
Unlike barcode scanners, RFID readers do not require direct line of sight to collect data. Instead, the reader’s antenna sends a wireless signal to nearby RFID tags that wake them up and transmit their own return signal.
The first thing to consider is the size of the reading zone. The second is how you will power the reader. The third is connector types. The rule is that opposite connectors connect, for example, RP-TNC Female to RP-TNC Male.
The RFID Reader
RFID tags assign a unique electronic ID to a physical article. They communicate with RFID readers via short-range RF signals. The RF signal is interrogated by the RFID reader, which identifies and decodes information stored in the tag.
An antenna connected to the RFID reader obtains a wireless signal reflected by the RFID tag and transmits it to the reader’s data processing module. The RFID Reader RF signal carries information about the RFID tag, such as its signal strength, phase value and Doppler shift.
The RFID reader’s data processing module determines the unique identification number (UID) and other information about the tagged item, such as the object type, location or temperature. The RFID reader sends this information to the database or other computer system where it can be accessed and processed.
One RFID reader can collect data from a number of tags simultaneously, unlike barcode scanners that require each item to be scanned individually. This can save time and effort for tasks such as scanning inventory or completing a stock check. In addition, an RFID reader can operate without direct line of sight with the tagged item, so objects such as machinery, construction materials and containers can be scanned. This capability makes RFID systems ideal for use in harsh environments and for applications where physical articles must be scanned, such as on oil rigs or in animal control.
The RFID Tag
RF tags are small, flat and contain an integrated microprocessor that stores data and transmits it when coupled with a reader. They’re robust and can be encased in materials that protect them from harsh fluid, chemical or rough handling environments. They can also be incorporated into the surface of a product or container. In fact, there is a huge range of RFID tag types available, including options that are suitable for use in hazardous (ATEX) or corrosive environments.
An RFID tag can be powered either passively by a built-in capacitor, or with a battery. In passive mode, the microprocessor in the tag is active only when coupled with a reader, sending out signals at pre-set intervals and receiving back data from the reader. In active mode, the chip is constantly powered on.
The RF signal emitted by an RFID tag is detected by the RFID reader’s antenna, which transmits the same RF signal to all tagged items within its radius of operation. The reader can then identify and read the tagged item’s data or serial number. It can also determine the exact location of a tagged item by obtaining RSS (received signal strength) information from a number of different readers that have scanned the same tag over time, calculating the target’s actual position. In this way, RFID is able to achieve real-time locating and tracking without the need for line-of-sight detection or physical contact.
The Antenna
Antennas convert electric power into electromagnetic energy (or radio waves) and back again. They also act as radiators, spreading electromagnetic radiation into free space and sensors, sensing electromagnetic waves present in that space and collecting them.
An antenna’s electromagnetic field can affect particles of matter and create magnetic fields around it. It can also transmit and receive RF signals, but the most important thing for our purposes is that it can capture the backscattered signal from the RFID tag.
The antenna’s frequency, the polarization of its radiation pattern, and its gain are all important characteristics when it comes to detecting breathing. The more focused the antenna is, the higher the gain. This is achieved by adding more radiating elements.
A directional antenna is preferred to an omni-directional one because it can focus the signal to a desired location, making contact smart card it easier to monitor. However, a directional antenna tends to have more losses, which reduce its efficiency.
The reader’s sensitivity and detection range are also important to consider, as is the type of RFID tag used. Deterministic detection is typically faster than probabalistic detection, but it also requires that the underlying binary code of each tag be read bit-by-bit. To prevent a tag from being read multiple times, the reader can use one of two anti-collision algorithms: frequency hopping or a pseudorandom sequence.
The Power
Whether it’s components on an assembly line, raw materials waiting to be sent out for manufacturing or tools, laptops and other expensive equipment that are easily lost, RFID systems allow you to track them all without counting each individual item. This translates into time and cost savings for organisations. Fixed RFID readers are placed around oil rigs to identify personnel, for example, and are used on toll roads to register payments made by drivers with prepaid accounts.
The most obvious benefit is the heightened inventory control that RFID delivers for retailers. In addition to the basic information like product numbers and descriptions, the data can provide insights into things like which products are selling best and where — helping to avoid out-of-stock situations that erode sales and customer satisfaction.
Warehouses can also leverage RFID to automate workflows, reducing manual processes, increasing efficiency and cutting operating costs. RFID portals stationed at dock doors can automatically scan products in and out of inventory, allowing for more accurate tracking of goods as they move across the facility. For more complex warehouse solutions, RFID tags can be glued to the side of containers to track their movements across multiple zones within a distribution center, eliminating the need for workers to manually pinpoint pallet and SKU locations. RFID can even track products as they are loaded onto and unloaded from a conveyor or truck, eliminating the need to count items.