Medium waves (also hectometer waves ) - a range of radio waves with a frequency of 300 kHz ( wavelength 1000 m) to 3 MHz (wavelength 100 m).
Medium waves (along with short ones ) are the most used range for broadcasting (526.5-1606.5 kHz) with amplitude modulation . The frequency grid of broadcasting stations in Europe is 9 kHz, in the Americas - mainly 10 kHz, most radio stations still use modulation with two side bands and an unsuppressed carrier ( type A3E ). A range of 160 m (1.8 ... 2.0 MHz) is allocated for amateur radio communications .
Medium waves can propagate over fairly large distances - hundreds and thousands of kilometers - due to the bending of the earth's surface, and also (mainly at night) reflected from the ionosphere .
The frequencies 455, 465 and 500 kHz are special - they are used as intermediate in most superheterodyne receivers of long, medium and short waves. Frequency 500 kHz, in addition - the standard frequency for distress signals .