very low range RF system

hello everybody, my name is Gustavo, i´m from Brasil and i´m new here!!!

i need to make a divice that when closely to another it can detect the proximity.
but it have to be fast to detect (less than a second) and must be low consumption and low weight.
the range of the detection is about 2 meters, the best is between 1 to 2 meters.

i already saw RFID, Bluetooth, magnetic and others technologys but i think that the best is RF.
in the web i saw the cc1000 and cc1050 chips that are perfect to the situation but i dont know if i can get the low range with that chip....

please, can someone help with it?

many thanks to everybody


bye