Many companies have already discovered the benefits of implementing RFID into their systems. Traceability within the manufacturing process provides a competitive advantage of both efficiency and profitability. RFID tags are a major component of this technology. But it’s important to select the correct type for your specific application. These tags are classified into categories based on how they obtain power and how they use that power. The three categories are as follows:
- Passive tags
- Semi-passive tags
- Active tags
Understanding the difference between these can help narrow down your decision when looking into implementing RFID systems to your process.
Passive tags do not have their own power source. The tag receives power only when the RFID reader is in range. These tags are limited since the power supplied is minimal. The biggest advantages of passive tags are that they are small and inexpensive. They can be useful in specific applications where space is limited. Also, if the environment in which the tag is being placed is harsh, the passive tag may be a good option because it can be cheaply replaced if damaged. Since these tags do not generate power, their read distance of just a few inches to about two feet is much shorter than others. Passive tags are also limited to the amount of data storage they possess. Depending on the application this can be an advantage or disadvantage.
Semi-Passive tags, as the name implies, are similar to passive tags in that they do not have an active transmitter. They still require an RFID interrogator to be in range for the device to work, although the semi-passive tags have their own battery to power the IC. If you are looking for longer read ranges than the passive tag, this could be an option. Since the read range of the passive sensor is solely based on how far away the interrogator can power the device and not the signals coming in, adding a battery unit to the semi-passive tags increases this distance. These distances can range up to 100 feet. Another advantage is the amount of data they can store. These added features do come with added costs. The onboard power supply also makes these tags larger and heavier. The electronics inside the tag are susceptible to harsh environments like high or low temperatures, resulting in shorter lifespans.
Active tags have both a battery and transmitter built within their housings. The typical read range is again increased to around 300 to 750 feet depending on the battery power and the antenna. This allows the tags to store more data with their increased memory capacity. Active tags display the most configurability in comparison to passive and semi-passive tags. They can be set up to conserve battery power when the interrogator is out of range and respond only when the reader is within range. They can also be set up as a beacon, which is when the tag does not wait until it receives a signal from the interrogator. Instead, the active tag can be configured to send the information in set time intervals. Since active tags contain an active transmitter, they can contribute to radio noise. They are also more expensive and usually larger in size and weight due to the increased electronics within its housing.
It’s important when selecting a tag for your RFID system to consider the application needs and the advantages and disadvantages of these different options.
