Here is final project from two Cornell students who researched, designed and implemented an RFID proximity security system.

They decided to build a proximity security system as their student id cards supported both magnetic strip and RFID tags. Many of the controlled areas on campus were switching to proximity entry systems.

The maximum range of their proximity card reader is about 1.5 to 2.0 inches from the antenna coil.

There site is well documented and they did a great job.

Since RFID is getting so much bad publicity lately, it is good to see some examples of the technology put to good use.

Proximity Security System