RFID Reader

Hey guys. I'm trying to make a long-range RFID reader which could read 125kH passive RFID tags at a minimum distance of 7cm, better 10cm. I'm planning to use an Arduino Uno or Mirco for this purpose. But I'm not sure of what reader module should I use. It should also have a "big" reading-area so that you can't miss the reader.
Please help me.