Appleton and Barnett's Experiment to Measure the Height of the Ionosphere

Marconi's first demonstration of transatlantic radio communication on 19 December 1901, from Poldhu in Cornwall, U.K., to St John's in Newfoundland, Canada, was an important landmark in our subject. However, it was evident that the propagation path was far from line-of-sight, and the exact propagation mechanism was unclear. In an entry in the Encyclopaedia Britannica in 1902, Oliver Heaviside postulated the existence of a conducting layer in the atmosphere that would reflect radio waves and allow long-range propagation, and Robert Watson Watt proposed the name “ionosphere” in 1926.