Last week, slowly backed my 2007 citroen badged ducato out of a customers driveway. Heard the aerial hit a low branch, no problem its the same branch I rubbed under on the way in.
Heavy rain here on wednesday. As I pulled away from the shop and turned left, about half a litre of water fell out of the overhead parcel shelf onto me and down the A post.
Tomorrow I'm stripping out the shelf and head lining and I'm going to seal up the aerial mounting area.

Just a warning to anyone that thinks the aerial will cope whilst backing up under low whatsits.
Hope this helps.

I had a similar experience with my doblo.
As the aerial was a bit loose I assumed water was getting in.
I removed the shelf & headlining & discovered the real reason for all the water...
Condensation. The metal roof was sodden. As more water condensed, rivers seemed to form, these followed the forward curve of the roof then tried to find their way out...

https://www.fiatforum.com/doblo/221950-water-dripping-inside.html

After dabbing all the water with old towels I put everything back.