Been there, done that
Is this on an FC? If it is, your options are rather limited if you have the factory wrap around spoiler.... Can't mount a rubber ducky antenna and keep the spoiler, so that narrows choices down to:
1. Fix the stock power antenna. The plastic "chain" in there is the part that breaks. I got the replacement mast kit for mine a few years ago from Ray Crowe. Mazdatrix and Atkins stocked them too, but as usual brother Ray had the best deal.
2. If the mast kit is now NLA, you might try a generic power antenna. Look for a quality unit and expect to pay for it. Try Crutchfield.com and call them for recommendations on a suitable replacement. They do exist, I just don't remember what brands/models.
3. This is a long shot, as it didn't work for me, but some FCs (S5's at least) have a 2nd dipole antenna element embedded in the stock windshield. If you have that, you can plug that antenna in and see if you get decent reception. I didn't - reception sucked. To see if you have it, look for 2 thin wires running vertical along the center of the windshield)
4. Another option is an aftermarket roof-mount patch element or rubber ducky antenna. Or you can source one of those antennas from a late-model wreck in a pick & pull yard. I didn't seriously consider this because I didn't want to have to drill holes in my roof.