David Edward Hughes - Invention of Radio

Invention of Radio

In 1879, Hughes discovered that sparks would generate a radio signal that could be detected by listening to a telephone receiver connected to his new microphone design. He developed his spark-gap transmitter and receiver into a working communication system using trial and error experiments, until eventually he could demonstrate the ability to send and receive Morse code signals out to a range limited to 500 yards (460 m). Prominent attendees of the demonstrations were Sir William Crookes Sir William Henry Preece, William Grylls Adams, and James Dewar.

Hughes demonstrated his technology to representatives of the Royal Society in February 1880, but it was incorrectly dismissed as merely induction. While Hughes was continuing his wireless telegraphy research, Hertz's papers were published, and then he thought it was too late to bring forward these earlier experiments. Hughes' work was not published until a brief mention of it in 1892, and a full magazine article was written about it in 1899. A book about it was published in 1899 and 1901. However, his work was not done in obscurity. His substantial contributions to science achieved wide recognition during his lifetime, from his peers within the scientific community.

Despite the initial erroneous dismissal of his radio system, he was elected a Fellow of the Royal Society in June 1880, and won their Royal Medal in 1885. He became one of the most highly decorated inventors of his time. His many accolades made him known to radio pioneers who would refine his work in later years.

Indeed, the Hughes Medal was created by the Royal Society of London in his honor, to be awarded to other scientists "in recognition of an original discovery in the physical sciences, particularly electricity and magnetism or their applications". A listing follows of Hughes Medal recipients honored for achievements directly applicable to the advancement of radio science and technology (click to show table).

Hughes "abundantly proved his claim to have been the first to transmit actual signals..." "Hughes's experiments of 1879 were virtually a discovery of Hertzian waves before Hertz, of the coherer before Branly, and of wireless telegraphy before Marconi and others."

Notably, the radio receiver technology of David E. Hughes surpassed the simplistic spark-gap device that would first be studied by later radio researchers. He discovered that his microphone design exhibited unusual properties in the presence of radio signals. He experimented with the discovery, and described his creation of both the device classically known as a "coherer", and an improved semiconductor carbon and steel point-contact rectifying diode, which he also called a "coherer". The point-contact diode version of the device is now known as a crystal radio detector, and was the key component of his sensitive crystal radio receiver.

Point-contact diodes had been independently discovered by other scientists. They were later studied and described in detail by J.C. Bose, in his research on their use in radio receivers. John Ambrose Fleming earned a Hughes Medal after he improved the Hughes diode receiver component with his invention of a vacuum tube diode, which could be operated more reliably than the semiconductor technology of the time. Fleming's U.S. patent for the vacuum tube rectifier diode was invalidated due to the prior art of the other diode researchers who preceded him.

Elihu Thomson recognized the Hughes claim to be the first to transmit radio. Hughes himself said "with characteristic modesty" that Hertz's experiments were "far more conclusive than mine", and that Marconi's "efforts at demonstration merit the success he has received... the world will be right in placing his name on the highest pinnacle, in relation to aerial electric telegraphy".