Mitsubishi OUTLANDER Manual page 569

Comfort controls
Reflection
The reason why one can hear FM but not AM in parking
garages, under bridges etc., is that FM signals, unlike AM sig-
nals, are reflected by solid objects such as buildings, etc.
Because FM signals are easily reflected by buildings, this can
also cause reception disturbances.
The direct signal from the broadcast station reaches the antenna
slightly before the reflected signal. This time difference may
cause some reception disturbance or flutter.
This problem occurs primarily in urban areas.
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5-138
Cross modulation
If one listens to a weak station and is in the vicinity of another
strong station, both stations might be received simultaneously.
FM stereo reception
Stereo reception requires a high quality broadcast signal. This
means that types of disturbances mentioned previously become
more marked and the reception range is somewhat diminished
during stereo reception.