A motor vehicle antenna system is disclosed for receiving electromagnetically radiated signals in the FM radio broadcast frequency range. The antenna system includes a magnetic current receiving, conformal, substantially rectangular truncated slot antenna. The slot antenna is defined in part by a substantially horizontal portion of a conductive periphery of a window opening of the motor vehicle. The slot antenna is further defined in part by a conductive trace integral with a glazing panel mounted in the window opening. The conductive trace extends horizontally a distance equal to one-half a wavelength in the FM broadcast frequency band. The ends of the trace are effectively connected to the conductive periphery of the window opening. An electrical lead is provided for carrying signals from the slot antenna to a radio receiver, having a first conductor connected to the conductive window periphery and a second conductor coupled to the slot antenna, such as by a network feed structure integral with the windshield, optionally forming an electrical junction with the trace. The side points of the trace are effectively connected to the conductive periphery, e.g., by direct physical connection using an electrical lead, or by providing vertically-extending end traces parallel and proximate to opposite vertical portions of the electrically conductive periphery of the window opening.