A new type of concealed AM/FM antenna has been designed, installed, and tested in several automobiles. The antenna is a planar slot having an annular aperture opening in a conductive film. Best reception -was achieved by locating the planar antenna in the roof area of the vehicle. Antenna radiation data indicated the slot antenna has better AM and like FM reception as compared to that of the production mast antenna. Highway listening tests in urban, rural, and fringe broadcast areas indicated similar reception characteristics. Other advantages offered by this antenna technology are reduction in damage, wind noise, weight, and aerodynamic drag as compared to that of mast antenna technology.