http://wiki.sdn.sap.com/wiki/display/ABAP/Download+File+in+UTF-8+encoding
The correct Unicode Codepage are
UTF-8 Encoding: 4110
UTF-16 Big Endian : 4102
UTF-16 Little Endian : 4103.
http://scn.sap.com/thread/1683149
Please check the above. Hope it helps.