Alternatives to Radio Transceivers

Question

So i am creating a haunt project that needs a way of detecting when an Arduino passes it and makes that Arduino do something. the problem I'm having is that none of the transmitter and receiver that has a small enough range that won't interfere with other patrons walking through on the other side of the wall. does anyone have any ideas what i can use?

Answer 1

There is a discussion of a similar question at the Arduino forum where they leaned towards passive UHF RFID tags.

If your budget stretches to it, there would be a range of active RFID tags that might suit.

There’s a good intro to RFID at Sparkfun, and Wikipedia has a good starting reference point.