Is this antenna a LEGO piece?
I've never seen that part until now, and it's certainly not in the antenna or bar bricklink categories. I'm fairly confident it's not LEGO.

However, it would be far more interesting to know what it is, but that's not easy to search. A few Mega Bloks parts have been catalogued, but your part isn't there either (I could only check categories bar, weapon and tool/gear before I got sick, though). Considering that database is far from complete, it doesn't mean it's not Mega Bloks, though.

Actually, I think there's a good chance it IS Mega Blocks: the antennas on the Repzyllian Trekker and the Gyro Fighter look very much like yours.