AM Power vs FM
Why does AM have longer range than FM?
AM has longer range because its wavelengths are so much longer. An AM wave
is about 500 meters long. An FM wave is only around 10 meters long. An AM
wave seldom notices things as small as cars or houses as it travels through
the air. An FM wave can be affected by anything at least a few feet wide.
The frequencies used in AM broadcasting are reflected by the ionosphere
and by the earth so these frequencies can bounce back and forth. On the
other hand, the frequencies used in FM broadcasting are not reflected by the
ionosphere, so the reception of these signals is pretty much "line of
Because the wavelength of the signal is longer, thus, it can reach farther
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Update: June 2012