Welcome to the garage.
Not familiar with the power antenna you have, but most probably a gear broke or is worn. You will have to remove the power antenna assy and open up the gearbox to see if its something repairable.
JEEP Grand Cherokee 4.7 Lmtd 2004
HID 8000K in low and fog / Quad Squad member
KYB Gas-a-Just shocks / Pirelli Scorpion ATR 245/65/17 - Transgo reprogramming shiftkit.