Pure Highway problem

[24lemons]

I bought a Pure Highway 400 DAB receiver for my car 2 days ago. I have installed it exactly as the instructions describe but in my morning commute I barely get a signal.

My previous car had an AutoDab system with a similar window mounted aerial to the Pure Highway and on the same daily drive it didn't miss a beat.

Are there any decent upgrade aerials available which are windscreen mounted? I dont really want to go down the line of external aerials if I can avoid it.

Thanks!