The question as to who invented the radio does not have a specific answer. There have been numerous theories and patents filed for credits. In case of the discovery of the radio, one fine understanding is that many theories and principles went into a completed circuit of the radio. These were contributed by not one, but many researchers. The theory behind each discovery led to the practical experimentation of the same, but in most cases, by another researcher. We can say that the radio was more of a discovery formed by contributions by many researchers, and not an invention that gave credit to a single inventor.
The first name, however, that bags credit is Guglielmo Marconi. He was the first person to successfully apply the theories of wireless technology. In 1895, he sent out the first radio signal, which consisted of the single letter 'S'. With this, he was granted the world's first patent for the radio. However, with time, it was proved that many theories used in the making of a radio were actually first patented by Nikola Tesla. Therefore, in 1943, the government authorized the patent for the radio invention to Tesla.
But many discoveries have been documented in the history of radio, the patents of which are controversial (some even till date). Below is the timeline of events and research that have made the radio the greatest, yet the most controversial discovery.
History and Invention of the Radio
The roots of the radio trace back to the early 1800s. Hans Ørsted, a Danish physicist, laid the foundation of relativity between magnetic energy and direct current, in 1819. This theory later formed the basics for other progressive inventions of physicist André-Marie Ampère, who experimented with the formulations and invented solenoid.
This invention led other scientists and researchers to explore this theory further for practical use. In 1831, Michael Faraday from England developed the theory which stated that change in the magnetic field in an electric circuit could generate current or electromotive force in another wire or circuit. This theory was known as inductance. In the same year, Joseph Henry, a professor at Princeton, was simultaneously working on a similar theory of electromagnetic relay. Both of them were credited with the patents respectively. Henry bagged the patent for self-inductance and Faraday for mutual inductance.
The onset of the 1860s saw yet another scientific breakthrough. James Clerk Maxwell, a Scottish physicist and a professor at King's College, London, extended the theory that Joseph Henry and Michael Faraday introduced. He contributed greatly to the research on electromagnetism between 1861 to 1865. He predicted the existence of magnetic waves, and that the speed of their travel is constant.
Mahlon Loomis is called the 'First Wireless Telegrapher'. In 1868, he demonstrated a wireless communication system between two sites that were 14 to 18 miles apart. Amos Dolbear was a professor at Tufts University, and received a U.S. patent for a wireless telegraph in March, 1882.
In 1886, another great discovery stunned the scientific world. Heinrich Hertz, who was a German physicist and mechanician, discovered electromagnetic waves of energy which were much longer even if they traveled at the speed of light. In 1888, he became the first person to prove the presence of electromagnetic waves by constructing a system to create and detect UHF radio waves. He is credited to designing the first receiver and transmitter for the radio. His name is used as the standard unit for radio frequencies, which is 'Hertz'. The Hertz designation was an official part of the international metric system in 1933.
In 1892, Nathan Stubblefield first demonstrated wireless telephony. He was the first to use wireless telephone to broadcast human voice. It is believed that Stubblefield invented the radio before Tesla or Marconi. However, his devices appear to have worked by audio frequency induction or audio frequency earth conduction, rather than radio frequency radiation for radio transmission telecommunication.
The next big successful leap in the history of radio invention happened consequently. In 1892, Nikola Tesla designed the fundamental design for the radio. He had to his credit, the invention of 'Tesla' coil, also called the induction coil, invented in 1884. Nikola Tesla was an engineer with brilliance. In 1893, he demonstrated wireless transmission to the public. Within a year, he was all geared up to demonstrate a wireless transmission over a distance of 50 miles. However, in 1895, a building fire struck his lab, which gutted all his research papers and work. In 1898, a radio controlled robot-boat was patented by him. This boat was controlled by radio waves and shown in the Electrical Exhibition in Madison Square Garden.
Sir Oliver Lodge was experimenting with wireless transmission. In 1894, he designed a device called a 'coherer' up to perfection. This was a radio wave detector, and the basis of the early radiotelegraph receiver. He was showered with international recognition, as he became the first human to transmit a radio signal.
Alexander Popov constructed his first radio receiver containing a 'coherer' in 1894. He then invented the lightning-recording antenna in 1895. This was then modified as a lightning detector and demonstrated before the Russian Physical and Chemical Society, on May 7, 1895. This day is remembered by the Russian Federation as 'Radio Day'. It was in March 1896, that transmission of radio waves was done across disparate campus buildings in St. Petersburg. A radio station was built on Hogland Island to facilitate two-way communication by wireless telegraphy between the Russian naval base and the crew of the battleship General-Admiral Apraksin. This was done as per Popov's guidance in 1900.
It is during this time that a controversy was in the making. In England, in 1895, Guglielmo Marconi was also working on wireless communication. He got success with demonstrating wireless communication of radio. His first radio signal was sent and received in 1895. In 1896, he patented this discovery, and researched further for practical and commercial use of the radio. In 1899, a 26 mile link was laid between two cruisers containing Ducretet-Popov devices in France. In the same year, the first wireless signal was sent across the English Channel. In 1902, the letter 'S' was telegraphed from England to Newfoundland. This was the first triumphant transatlantic radiotelegraph.
Nikola Tesla did file for the first patent of inventing the radio in 1897, which was granted to him in the United States in 1900. Marconi too filed for a patent in USA in the same year (1900), as the first inventor of the radio. However, it was turned down, as it used many of Tesla's already patented inventions contributing to the radio.
In 1903, Valdemar Poulsen began arc transmission to create high-frequency alternators to send radio waves. The New York Times and the London Times knew about the Russo-Japanese war due to radio in 1903. In the next year, a commercial maritime radio network was established under the control of the Ministry of Posts and Telegraphs in France.
In 1904, the next three applications by Marconi for patents were turned down by the U.S. government. However, it is believed that Marconi had strong financial support. His radio company was flourishing and this backing helped him. The patent for radio invention was reconsidered and credited to Marconi in 1904. With this, he bagged the universal credit for the inventor of the radio.
In 1894, Sir J.C. Bose first demonstrated radio transmission in Calcutta, India, before the British Governor General. However, he did not patent his work. A few years later, in 1899, he demonstrated the same transmission of 'mercury coherer with telephone detector', in the Royal Society of London. He solved a major issue in radio development, which was the Hertz system being unable to penetrate walls or any other physical obstruction. It is believed that the coherer used by Marconi worked on the coherer design invented by Bose. No patents were filed by Bose, until 1901, when he applied for a patent for the invention of the radio. It was granted to him by the US government in 1904. However, by then, the invention of the radio had already been credited to Marconi, with worldwide recognition.
Reginald Fessenden was a Canadian inventor reputed for his achievements in early radio. The first audio transmission by radio in 1900, the first two-way transatlantic radio transmission in 1906, and the first radio broadcast of entertainment and music in 1906, were his three significant milestones. Fessenden concluded that he could devise a better system than the spark-gap transmitter and coherer-receiver combination that had been put forth by Lodge and Marconi. In 1906, he designed a high-frequency alternator and transmitted human voice over the radio.
From here on, development of the radio for more practical use began. In 1907, Lee Dee Forest invented the vacuum tube amplifier, which was known as the 'Audion', and enabled the amplification of signals, and also the Oscillion'. Human voice could be now transmitted instead of codes.
In 1910, a broadcast from the Metropolitan Opera House in New York city could be heard on a ship that was 12.5 miles away.
1911 to 1930 was the period of the growth of the radio. The Radio Corporation of America was founded. This was done by combining General Electric, Western Electric, AT&T, and Westinghouse. It was in this era that radio broadcasting began in Australia. Battery-powered receivers having headphones and valves were seen in France. A radio telephone concert was broadcast across the Atlantic Ocean to several receivers. In this era, radio broadcasting started in Shanghai and Cuba. The first regular broadcasts took place in Belgium, Norway, Germany, Finland, and Switzerland.
Edwin Howard Armstrong was also known as the inventor of the Frequency Modulation, i.e. FM. In 1933, he discovered that a constant signal could be easily picked, rather than a fluctuating frequency. So any transmission on the radio could be fine-tuned easily, even for an average person.
Controversy did not end here. In 1943, just a few months after Nikola Telsa's death, the U.S. Supreme court reconsidered Tesla's patent for invention of the radio. It concluded that most of Marconi's work for wireless transmission was already patented by Nikola Tesla. Hence, once again, the patent for the radio invention was deemed to be owned by Nikola Tesla.
Soon, radio became prevalent throughout the globe. What can be concluded from this is that, the invention of the radio has more than one inventor. Technology was being explored, and the stunning contributions by the many researchers mentioned above have made the invention of the radio possible.