RFID, or radio frequency identification, uses radio waves emitted by a read head to read information stored on read tags. The read tags then transmit the identification information back to a reading device via a built-in antenna. There are 3 main types of RFID tag technologies that are used to transmit identification information—passive, semi-passive, and active.
Passive tags: Do not have their own power supply. They relay information using radio waves, which induce a current in the chips inside the tags.
Semi-passive: Operate with batteries that assist with powering the sensor itself, but, like with passive tags, radio waves relay information from the readers.
Active: Have their own transmitter and power source, which is typically a battery. The power source is used to power the microchip circuitry inside the tag, and it broadcasts a signal that is received by the RFID reader.
What materials block RFID?
Most metals block RFID. In order to combat this, Pepperl+Fuchs has special tags that help prevent metal from interfering with the signal.
What size RFID tags should I use?
In general, the larger the tag, the broader the read range. This is because larger tags contain bigger coiled antennae. The larger antennae can more easily detect the wave that the reader sends out, which improves the chance of getting a signal.
Below are some tags Pepperl+Fuchs has to offer along with their upper read ranges:
- F203 tags mounted on metal, range is 12" to 32"
- Label tag, upper range is 24" to 60"
- Round tag, upper range is 20" to 50"
- F152 tag, upper range is 14" to 45"
What should I keep in mind when encoding RFID tags?
Polarization and power are key when it comes to encoding tags.
Polarization is essential to reliable object identification in certain applications. Types of polarization include linear vertical, linear horizontal, and circular. If all the tags are in the same orientation and you need extra power/range, linear polarization is best. If the orientation of the tag entering the read field is unknown or may vary, an antenna with circular polarization will be most useful.
Make sure that the power setting is adjusted to the level needed. Some applications may appear to require more power, but this is typically due to interference or a weak or poorly mounted tag. When too high a power is used, you are more susceptible to reading/writing unwanted tags. Check that tags in adjacent areas cannot be read to ensure an accurate read result.
Tightening Security with RFID
RF communication is still fairly vulnerable to outside interference. Preventing unauthorized access to and communication with tags and readers is one of the major challenges of modern RFID. The following steps can help ensure security:
- Increasing the number of channels as necessary
- Increasing the number of read attempts as necessary
- Encrypting data
- Password protecting sensitive data
- Utilizing a ‘kill’ feature to remove data