Abstract
Since the end of World War II, the number of daily frequency hours used by high-frequency (HF) broadcasting (also known as shortwave and band 7, 3-30 MHz) has tripled. Approximately 35000 daily frequency hours are carried in an HF spectrum that can barely accommodate half that amount. As a consequence, congestion is severe, and interference levels intolerably high. Attempts to remedy this situation by planning the high-frequency bands date back to 1947, but, thus far, they have not been successful. International planning conferences in 1984 and 1987 have shown a possibility for agreement; another conference is tentatively scheduled for 1992. Some broadcasters have attempted to solve their congestion problems by moving out-of-band, sometimes expanding their services int bands allocated to other services, such as amateur radio, fixed, aeronautical, and mobile. It is feared this trend will continue. The attempts that have been made to plan the HF bands in an effort to alleviate congestion are described and the outlook for the remainder of the 20th century is discussed.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
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