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Developments in high power longwave radio: A brief history

The early history of radio is really about longwave (VLF/LF). This paper presents a brief summary of the development of high-power longwave radio transmission from the beginning of radio to the present. The early experimenters discovered that reliable long-range communications was better at lower frequencies. By the mid 1920's all transoceanic radio communication was high-power VLF. High-power VLF/LF is still used for navigation, timing and submarine communications. There are five overlapping generations of high-power longwave radio transmitting systems involving changes in transmitter types, antennas and modulation formats. Each is discussed and examples of transmitting sites for each generation are given.