11-02-2010 11:18 AM
I've never designed an RFID device, and wonder if it can be used to solve the following "needle-in-a-haystack" problem:
I have a small widget, about the diameter of a pencil and 5-7cm long. The widget is valuable but can be lost in a pile of foriegn material which makes it hard to find.
Is there a RFID tag that is small enough to be embedded into this device, and a RFID reader that could then sense it from 4-8 meters away? Using a reader with a very directional antenna, the returned signal strength could be used to "zero in" on the widget's position.
So the questions are:
(a) is there a RFID tag that can fit in 5mm diameter x 50mm long device (cost < $5 @ qty=1000)?
(b) is there a RFID reader that (with appropriate antenna) can "see" the tag from 4-8m away ( cost < $100 @ qty =100)?
(c) is there a better way to do this?
11-04-2010 08:40 AM
This could possibly be achieved with a 2.4GHz active tag with something like Texas Instruments CC2500 or similar. The eZ430-RF2500 kit may be a good start. The board could probably be layed out to fit within the 5mm x 50mm device. BOM cost might meet the less than $5 budget. It will require a microcontroller, transceiver, battery, antenna.
Does the pile of foreign material contain metal or liquids? If it does it might be an issue with the reading of the tag.
11-10-2010 10:31 AM
I don't think there's any way to get an active tag with uC, xcvr, battery, & antenna in something the size of a crayon, so it would have to be a passive tag. I've seen tags used in the truck/offroad tire industry that look like a small axial inductor coil, but I haven't found any tech info.
The pile of material would not contain metal, but may have some moisture in the form of leaves or dirt.
Thanks for the ideas.
03-05-2015 12:23 PM