Please dont use two separate antennas if you are using both transmitter and receiver on the same PCB and never connect the both Tx and Rx directly to a single antenna in both the cases u will get your Reciever demaged.
The solution in my openion is only The "Duplexer or Circulator".
You may try the following link to know about the subject matter
or try to search out some Duplexer.
http://www.txrx.com/catalogs/...lowres.pdf.