AM-FM vs shortwave

AM-FM

shortwave

adj
  • Having a wavelength of approximately 10 to 100 meters. 

  • Capable of transmitting or receiving signals at such a wavelength. 

noun
  • Any frequency in this range, especially when used in broadcasting. 

  • Many stations broadcast on shortwaves. 

  • An electromagnetic wave having a wavelength between approximately 10 and 100 meters, corresponding to frequencies between 3 and 30 MHz. 

  • Downward radiation entering the earth's atmosphere that is in the shortwave frequency range. 

How often have the words AM-FM and shortwave occurred in a corpus of books? (source: Google Ngram Viewer )