English: Drawing of Guglielmo Marconi 's wireless telegraphy transmitting station in Poldhu, Cornwall , erected October 1901, with which he transmitted the first transatlantic radio message to St. John's Bay, Newfoundland on 12 December 1901, a distance of 2300 mi (3500 km) (although there is some doubt Marconi actually received this transmission). Marconi first built a round cylindrical antenna in summer 1901. When it blew down in a storm 17 September 1901 he hastily erected a temporary antenna consisting of 54 wires suspended in a fan shape from a cable between two 160 ft. poles, which was used in the actual transatlantic experiment. After the experiment in 1902 for permanent transatlanic service he built this antenna consisting of 200 wires in an inverted pyramid supported by four sturdy 210 ft (64 meter) lattice towers. The reason for the multiple wires of the antenna was to increase its capacitance to ground, to allow it to store more energy during each spark. An innovative 25 kilowatt inductively coupled spark gap transmitter in the station, designed by John Ambrose Fleming , produced radio waves probably at a frequency of about 850 kHz.

In 17 October 1907 it inaugurated the first regular transatlantic radio service, communicating by Morse code with a similar station in Glace Bay , Nova Scotia, Canada. These were the most powerful radio stations in the world at the time.