Longman Dictionary of Contemporary English
medium wave
noun
EXAMPLES FROM CORPUS
▪ That's why you can no longer get Radio 2 or Radio 3 on medium wave.
▪ You can receive Network 5 all over Ireland at around 700 and 900 on the medium wave.
WordNet
medium wave
n. a radio wave with a wavelength between 100 and 1000 meters (a frequency between 300 kiloHertz and 3000 kiloHertz)
Wikipedia
Medium wave
Medium wave (MW) is the part of the medium frequency (MF) radio band used mainly for AM radio broadcasting. For Europe the MW band ranges from 526.5 kHz to 1606.5 kHz, using channels spaced every 9 kHz, and in North America an extended MW broadcast band goes from 535 kHz to 1705 kHz, using 10 kHz spaced channels.
Usage examples of "medium wave".
Over medium wave and short wave, a bogeyman can be brought into the room.