Poulsen Wireless
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Valdemar Poulsen patented his improved version of the Duddell Arc Converter, the Poulsen Arc, in 1903 (US Patent No. 789449, "Method of producing alternating currents with a high number of vibrations", filed 19 June 1903, issued 9 May 1905), which could generate power at higher frequencies up to 200 kHz, which was needed for efficient wireless communication. Shortly thereafter, he began demonstrating wireless telegraphy using his arc and selling his patent rights.

In 1904 after his patents had been filed, Valdemar Poulsen presented a paper on his early Poulsen Arc at the World’s Fair in St. Louis, Missouri which was subsequently published in 1905 in the Transactions of the International Electrical Congress, St. Louis, 1904, Vol. II. The paper was titled “System for Producing Continuous Electrical Oscillations”, and included an image of his 1904 Arc. In 1909, Cyril Elwell purchased the patent rights in the USA for $ 500K and formed the Poulsen Wireless Telephone & Telegraph Co. with Valdemar Poulsen owning a 10% share of the company. In 1911, the company name was changed to the Poulsen Wireless Corporation. In 1913, the company name was again changed to the Federal Telegraph Company. Poulsen Wireless and Federal Telegraph grew the 100 Watt Poulsen Arc of 1909 to the 1 Mega-Watt Federal Telegraph Arc of 1920. Valdemar Poulsen also sold European patent rights to the C. Lorenz AG of Germany. The USA Poulsen Wireless companies are briefly discussed in the book “Wireless Communication in the United States” by Thorn Mayes, published in 1989 by the New England Wireless and Steam Museum Inc. in East Greenwich, Rhode Island, USA.