RFID power supply options
Depending on whether they have their own power source, we distinguish between active, semipassive and passive RFID tags.
Active and semipassive RFID tags
Active and semipassive tags use an external power source (such as a battery) to power the chip. Active tags also use batteries to send radio waves to the reader.
Active tags are typically used to tag items that need to be read at distances of more than 35 meters.
A semipassive tag uses power supplied from the reader to send a signal. However, it uses an additional power source for other functions, e.g. in tags that measure temperature, the battery is used to power the circuitry that measures and records the temperature measurement data.
Passive RFID tags
The energy source of passive tags is the electromagnetic/radio wave produced by the reader-antenna system, so they respond with their signal only to the call signal sent from the reader. A few years ago, the reading ranges of passive tags were much shorter than those of active tags: about 6 meters, now the latest passive tags have a reading range of even more than 30 meters, such as the Dura 3000 container tag.
The production costs of passive tags are much lower, the lifetime is not limited by the battery, so passive tags are cheaper and can be used in more applications, especially in projects where the ratio of the price of the tagged object to the price of the tag is important.
Tag prices
Common passive RFID tag
est. €0,10 — €0,25
Encapsulated passive RFID tag
est. €0,80 — €4
Example semipassive RFID tag (with ability to record and monitor temperature)
est. around €30
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