Radio transmitter In 1899,
Guglielmo Marconi, the inventor of
radiotelegraphy, decided to attempt transatlantic radio communication. This would require a scale-up in power from the small 200–400 watt transmitters he had used up to then. Marconi contracted Fleming, an expert in
power engineering, to design a
radio transmitter. He designed the world's first large radio transmitter, a complicated
spark transmitter powered by a 25
kW alternator driven by a combustion engine—built at
Poldhu, Cornwall—which transmitted the first radio transmission across the
Atlantic on 12 December 1901. Although Fleming was responsible for the design, the director of the
Marconi Company had made him agree that: "If we get across the Atlantic, the main credit will be and must forever be Mr. Marconi's". Accordingly, the worldwide acclaim that greeted this landmark accomplishment went to Marconi, who only credited Fleming along with several other Marconi employees, saying he did some work on the "power plant". Marconi also forgot a promise to give him 500 shares of Marconi stock if the project was successful; he was bitter about this treatment. He honoured his agreement and did not speak about it throughout Marconi's life, but after his death in 1937 said Marconi had been "very ungenerous".
Fleming valve In 1904, while working for the Marconi Company to improve transatlantic radio reception, Fleming built the first
vacuum tube—the two-electrode
diode—which he called the "oscillation valve", for which he received a patent on 16 November. It became known as the
Fleming valve. The
Supreme Court of the United States later invalidated the patent because of an improper disclaimer and, additionally, maintained the technology in the patent was known art when filed. Fleming's diode was used in
radio receivers and radar for many decades afterwards, until it was superseded by
solid-state electronic technology more than 50 years later.
Patent dispute In 1906, American inventor
Lee De Forest added a
control grid to the valve to create an amplifying vacuum tube RF detector called the
Audion, leading Fleming to accuse him of infringing on his patents. De Forest's tube developed into the
triode, the first electronic
amplifier. The triode was vital in the creation of
long-distance telephone and radio communications, radars, and early electronic digital computers (mechanical and
electromechanical digital computers already existed using different technology). The court battle over these patents lasted for many years with victories at different stages for both sides. == Personal life ==