The question is which antenna? If you mean the KU-Antenna, then the answer is from the keyboard on panel R11, switch on panel R13L, switch and knob on panel A1U. If you mean another antenna, please be more specific so we can help, even if, as far as I know, there isn't any other antenna to activate in the sim. If you want more detailed infos on the panels, go to the website of NASA and search for the "Shuttle Crew Operations Manual", it's free to download, along with plenty of other Shuttle manuals for various systems. Hope this helps you
