How to design a safety barrier for RFID antenna?

I need to use a RFID antenna (reader) in a Zone 0 classified area, and it is connected to an apparatus which is located in a non-classified zone. My question is, what type of circuit do I need to build inside my equipment (i.e. not a separate barrier) in order to make it intrinsically safe? A sample circuit and/or some design tips would be great.