2005 Dodge Stratus Owner Manual Coupe - Page 219

FOR PLEASANT DRIVING 219 Signal transmission FM signals do not follow the earth's surface nor are they reflected by the upper atmosphere. For this reason, FM broadcasts cannot be received over long distances. AM signals follow the earth's surface and are reflected by the upper atmosphere. For this reason, AM broadcasts can be received over longer distances. Weak reception (fading) Because of the limited range of FM transmissions and the way FM waves spread, fading usually occurs with FM reception. When the broadcast is blocked by mountains or similar obstructions, reception disturbance may result. Reflections 6 H12G0020 The reason why one can hear FM but not AM in parking garages, under bridges etc., is that FM signals unlike AM signals, are reflected by solid objects such as buildings, etc. Because FM signals are easily reflected by buildings, this can also cause reception disturbances.