Hi Folks, had a search but i'm pants with computers

2 aerials in boot of A4 cab but what do they do?

No radio reception at the moment and i checked the co-ax cable and does not seem split at the seals of the boot so think it could be an aerial antenna. Some rust on them at bolts etc so think water has maybe got in at some point.

What do they do and which is most likely culprit?

Many Thanks