Hi

I would like to know in RFID, why lower frequencies have shorter read range as we can see on this website
http://vero.solutions/technology/rfid/
Usually, higher frequencies have less coverage. Why in RFID is it the oposite ?

thanks you

 

It's a trade off between distance and speed for multiple reading, so for instance a Pet tag will use 125kHz and is not affected by metal objects,water or skin effects and uses a shorter range upto 0.3mtrs with a single loop coil slower speeds.

Shop tags like books or clothing use 13Mhz need a bigger antenna usually located at the door entrances, are limited by skin effect and can be masked with tin foil to fool the system, but can scan multiple devices at once faster speed.

Then there is Uhf readers usually for Cars like parking permits, toll booths etc, faster reading speeds, bigger antenna system needed multiple scanning and is affected by metal Objects in it's path.