Abstract:The observational evidence for long-range propagation of high-frequency radio signals began to accumulate in 1926 when transatlantic communication links were established. In 1927, signals were detected that had propagated over large distances or circled the earth with little attenuation.Long-range and round-the-world (RTW) signals showed preferred periods of occurrence. Relatively high angles of incidence (20 ø relative to the horizontal) of such signals at the receiver paired with low attenuation ruled out co… Show more
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