OTTAWA, Ontario — With the advent of radio in the 20th century, the shortwave band (1710–30,000 kHz) soon became a hotbed of long-distance radio broadcasting. Used primarily by state-run international broadcasters, plus ham radio operators and ship-to-shore radio communications, the shortwave band was prized due to its astoundingly broad reach.
That reach was — and is still — made possible by the tendency of ground-based shortwave radio transmissions to bounce off the ionosphere and back to earth; allowing shortwave broadcasts to “hop” repeatedly, increasing a broadcast’s range while minimizing its decay.
[…]At the height of the Cold War, the shortwave bands were packed with content as the Voice of America and West Germany’s Deutsche Welle (Voice of Germany) traded ideological punches with Radio Moscow and East Germany’s Radio Berlin International. This is because analog shortwave radio broadcasting was the only way for both sides to make their political cases cross international borders: There was no satellite TV, let alone any internet.