BATTERY ASSISTED PASSIVE TAGS

If you need greater read distances or quicker response times than can be achieved with ordinary RFID tags, the answer may be in battery assisted passive tags.

Conventional RFID tags use the power from the readers signal to turn on and then to run the chip, power the memory and power the transmission back to the reader. As a result the distance between the reader and the tag has to be close enough for the power to be collected.

With battery assisted (or semi-passive) tags, they only use the power of the reader to identify that reading is in progress. Then, they use their own on-board battery to power up, run the chip and the memory and transmit and receive data.

Because the tags are self powered they can transmit their data over greater distances and they reply more quickly to the reader.

There are some drawbacks, though, but these are often overcome by the befits of faster, long distance reading. The tag’s battery has a defined life (However, battery life can be over 5 years, after which tags behave as passive ones do so nothing is lost). Battery assisted tags are also bulkier than their passive equivalents, although, in comparison to most UHF long range tags the difference in size is small. They are more costly too.

Battery Assisted Passive Tags

A battery assisted tag gives greater read range and more reliable reading

Key FeaturesBenefits
Works with standard RFID readersUses existing UHF readers, avoids the need for specialised or non-standard reader devices or software.
Higher success rateRe-reading is rarely needed. Reading of tags passing through a portal is far more reliable.
Longer read ratesMakes the design of systems easier, may make the positioning of readers and antenna less critical.
Lower latencyTag responds to the reader more quickly; important if the tag is triggering some other process.

CoreRFID has worked with battery assisted passive tags on a number of projects. You can learn about our experiences from our case study of Vaillant Group’s which uses them in manufacturing operations in the UK.