The RFID readers are being used everywhere for tracking objects and assets management. Since its first use as a simple radio-active device to track animals and trains, it has developed so much over time and now there are a lot of varieties of RFID readers from short-range to long-range and active RFID readers to the medium-range RFID readers.
The RFID readers work based on radio frequency and the waves through the data are transmitted and received. So, the range of RFID reader depends on the radio waves and the frequency on which it works. The range of every RFID reader is influenced by various external factors such as the frequency of RFID system, the antenna it uses, the RFID tag it is connected with, and the environment in which it is being used. There may be even some other factors that will influence your RFID reader so if you planning to buy a medium-range passive RFID reader you should check with the seller what range you will be able to cover considering these factors.
When you buy any long-range RFID reader the seller normally claims its range usually referring to the use in the “free air” or the perfect environment free of any other electronic interference. So, if the seller is claiming the device would work in 80 feet distance you should understand that in the real work environment the actual read range would be shorter than its claim.
What are Active and Passive Tags?
Active RFID tags have a battery and a transmitter to broadcast signals just like our cell phones transmit signals to the base station. The battery in the active RFID tag turns on the microchip’s circuitry. On the other hand, a passive RFID tag has no power source and is activated when it receives a signal from a nearby RFID reader which sends out electromagnetic waves and when these waves reach the tag’s antenna the current is induced. Active RFID tags are used to read data from a long range and tracking high-value goods such as railway cars on a track. However, these active RFID tags are expensive as compared to passive tags.
Range of passive RFID systems
A passive UHF system RFID reader can read data from as long as 12m and has a faster data transfer rate as compared to the low frequency (LF) or high frequency (HF) system. One drawback of the UHF RFID is that it is sensitive to environmental interference and its performance may decrease in environmental interference. However, manufacturers have been able to design tags, antennas, and readers to maintain performance even in difficult environments.
The range of passive RFID systems is limited by the power of the tag’s signals reflected to the reader. Although the passive systems are limited in reading range, these are cheaper, smaller and easily manufactured as compared to the active RFID systems. A typical long-range passive RFID reader can work up to 5-7 Meters with built-in antenna and can be used in parking and Warehouse management etc.