OK...I'd sew the top right hand corner shut with a sewing machine so it wouldn't fly off the antenna. The bottom....uh....let me think about it. You're going to need something so it doesn't slip down.
BRB...
How would you display it on a car antenna?
A whole bunch of tape at the bottom of the flag...wrapped around & around the antenna...and then a BIG needle with probably buttonhole thread hand sewing the bottom of the flag to the tape.
Dang. I'm tired. I KNOW someone will come up with something better.
Ladies...help me here..