Re: RFID reader design

"Alchemist" <nobin.mathew@xxxxxxxxx> wrote in message
news:1147933948.642816.215130@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
I am trying to build a RFID reader for passive RFID tags like

http://availabletechnologies.pnl.gov/securityelectronics/rftagsdescription.stm.
These tags has got read/write range upto 10m.

My reader must be capable of reading tags at a minimum distance of 6m(
also the maximum).

I got few questions regarding this

1) Is it possible to read passive tags at a distance of 6m

Not sure. The general rule of thumb is that the diameter of the coil is
equal or twice the required reading distance. Also the required power
increases quickly with distance while the received signal decreases quickly
with distance. And all that has to be done on one antenna. My contacts with
a manufacturer of RFID systems once told me that it is already tricky to
receive signals when the loop runs around a door opening.

Meindert


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