Shortwave

"I remembered him tucking me in, and us listening to a person speaking Greek on the shortwave radio, and him telling me a story about New York's sixth borough." (37)

Shortwave:  a radio wave of a wavelength between about 10 and 100 m (and a frequency of about 3 to 30 MHz).

I turned on the old shortwave radio to hear classical music playing on one of the stations.