AM defogger grounding system for vehicle window antennas

A backlite antenna system for a rear window of a vehicle, said rear window being mounted in an opening in a vehicle body panel, said antenna system comprising:

• an antenna grid formed at an upper location of the rear window, said antenna grid including a plurality of antenna elements that extend substantially across the width of the rear window, said antenna grid further including first and second antenna end bus bars connecting the antenna elements at opposite ends;
• a defogger grid formed on a lower location of the rear window, said defogger grid including a plurality of defogger elements that extend substantially across the width of the window, said defogger grid further including first and second defogger end bus bars connecting the defogger elements at opposite ends;
• a first grounding strip positioned between the first defogger end bus bar and a first edge of the rear window and defining an FM slot gap therebetween, said first grounding strip being capacitively coupled to the vehicle body panel to provide an AM ground for the defogger grid;
• and
• an AM grounding line connected to the first grounding strip and one element of the defogger grid, said first grounding strip and said grounding line also providing an AM ground for the defogger grid.

A method of providing an AM ground for an antenna system in a vehicle, said method comprising the steps of:

• forming an antenna grid on a vehicle window of the vehicle that include a plurality of antenna elements extending substantially across the width of the window where the antenna elements are connected at each end by opposing first and second antenna end bus bars;
• forming a defogger grid on the vehicle window separate from the antenna grid that includes a plurality of defogger elements extending substantially across the width of the window where the defogger elements are connected at both ends by opposing first and second defogger end bus bars;
• forming a first grounding strip on the window adjacent to the first defogger bus bar to form a slot gap therebetween;
• and
• capacitively coupling the first grounding strip to the vehicle body panel through a seal that seals the window to the body panel.