Is the +12V for the aerial switched on?

I also have terrible reception, especially in town. The aerial is the one supplied with the device, glued to the top of the windscreen.

The supplied antenna, in case.

The aerial must be fitted exactly according to the instructions. Is it possibly defective (broken)?

Maybe the aerial. I bought everything new and it works

Are you operating the device with a splitter or with a "real" DAB antenna?