SJK9457

Hi all. I am experiencing poor DAB and FM signal on my standard radio. As it has the glass roof it has no external unit, do any of you know where the aerial is? My car is hatch Monte Carlo. The manual suggests may be within a window as mentions about not using metallic stickers nearby. I cannot see any marking on front screen (I am expecting it to look like heated screen lines?) but the glass carries Skoda branding so hoping not a non-genujne replacement fitted by previous owner. Any tips welcomed please. It is under warranty but do not want to trouble garage if it is an easy solve.