well, i can tell you three things you could do:
1)Hook up the antenna wire to the ACC. and everytime your car turns on, your antenna powers up
2)Connect antenna wire to any of the speaker wires from your head unit, with this your antenna powers on when your head unit is on, since it will be playing sound (antenna will be powered even if cds are playing, so that sucks)
3)Or connect it to a switch, and connect the switch to your 12V constant and just switch the antenna on when you need it. Annoying but works.
Other than that i cant help you to make your antenna power up exactly when you use the radio since your head unit has no remote antenna wire, but the above will work safely and fine. you decide now. hope i have been of help.