Place your Blackberry facedown in front of you.
Press the cover release button on the bottom of your device. Lift and remove the back cover.
From the top, use your fingernail to lift the battery out.
Remove the SIM card.
Remove the six 7.0mm Torx screws securing the rear case to the rest of the phone.
Use the plastic opening tool to remove the rear case.
The two antennas are built into the rear case. Replace this piece to replace the antenna.