"Long" range RFID

Other Hardware Sensors
1

I have a project where I'd like to detect presence based on RFID. Kind of like the keyless start/entry systems you find on cars.

I essentially need to be able to detect whether someone with an RFID card in their pocket is inside the car or just outside.

I'm guessing the solution is a few ID2s and some decent sized antennas, but what are other people's thoughts on this, and where can I source the antennas from?

2

To a close approximation near-field antennas are just coils of wire. The larger the coil the larger its detection area, but it will pick up more noise and interference...