The 'antenna' is the diff looking piece at the end of the antenna wire. That's the piece that needs to be up in the antenna tub near the end of the tube (pg 12 in the manual). If you leave it down on the chassis, make sure you do a range check to make sure you have adequate range before finding out the hard way you don't.
If range check indicates you have plenty, you're good. If you wind up with a reduced range, you'll have to try something else with the antenna.