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I'm a software guy so a bit on deep waters here so I thought I'd ask here. :-)

I'd like to understand if it is possible to have an RFID tag with the following properties:

weight: a few grams, size: around 5mm in diameter, length can be a few centimeters price: as cheap as possible range: a few meters or more

A person would then have a reader and walk around to find the items that have the tags on them getting a sound when a tag is in range or even better knowing somehow how close an item is.

Is this feasible with RFID? If not, where does it break?

Is there a better technology to use? I.e. have some kind of small and cheap "thing" to put on items that later can be used by a reader to find them?

Thanks in advance!

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  • \$\begingroup\$ I don't think you can do this with passive tags, you just cannot get the range you want without a powerful transmitter/receiver. There are a number of products out there using active tags, often Bluetooth LE, such as thetileapp.com (not a recommendation, just an example). \$\endgroup\$ – DoxyLover Jul 28 '15 at 17:28
  • \$\begingroup\$ @DoxyLover thanks for the comment. Hm, so would an active tag work? lowest price, weight and size? All properties are important but do have some margin for trade-offs. \$\endgroup\$ – murrekatt Jul 28 '15 at 17:32
  • \$\begingroup\$ @DoxyLover what would the range be with a passive tag? 1m? Less? \$\endgroup\$ – murrekatt Jul 28 '15 at 17:32
  • \$\begingroup\$ Passive range with a simple reader such as you'd find in a smart phone is, AFAIK, a few mm. rfidjournal.com/blogs/experts/entry?10684 states that with a "long-range" reader and UHF tags, you can get 100 meters. However, I suspect (don't actually know) that this would require a large tag. In this case, both the reader and the tag will probably be expensive. \$\endgroup\$ – DoxyLover Jul 28 '15 at 17:39
  • \$\begingroup\$ @DoxyLover Hm. I have been reading on rfidjournal.com too and also saw the mention about Mojix STAR that seems to have almost 200m range but totally unclear what the price is and sizes of tags. Most likely too much for my use case. So what's the next best? :) \$\endgroup\$ – murrekatt Jul 28 '15 at 17:57
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Yes, this is possible! You could use RAIN RFID (UHF RFID) using passive tags. The tags will be thin, flexible and cheap ($0.10-$0.05).

The read range depends on the output power of the reader, and the size of the tag. With a tag that has around 15cm2 area (3x5 cm or 2x8 cm) and a typical handheld reader, you can get up to 5 meter reading distance. With the tag size you require (5mm x few centimeter) the reading distance will be slightly smaller, but still a few meter.

Using the Returned Signal Strength Indicator (RSSI) value that comes out of the RFID reader you can get an impression on the distance between the tag and the reader.

A mobile RAIN RFID reader costs around $1000, but prices are expected to drop sharply in the next few years.

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