In the next few steps you will be removing the AirPort and Bluetooth antennas (shown in red) from the internal frame. Be very careful, as breaking the brackets will require replacing the internal frame.
We will first remove the AirPort antenna, located in the lower left corner of this picture.
Remove the following four screws securing the internal frame to the bottom housing:
Three 6.7 mm Phillips #00 screws
One 9.5 mm Phillips #00 screw
The screw in the lower right corner of this image is recessed deep in the internal frame and longer than the other three screws. A flashlight and a thin screwdriver aid in removal.
Lift the internal frame off the bottom housing, starting at the rear edge, until you feel the concealed edge connector on the motherboard disconnect. Then lift straight off, minding the bluetooth and 802.11 antenna cables.
When reassembling, the wifi antenna wire routes to the inside of the vent and then over the top of the vent.