Who Invented the Radio?
|Guglielmo Marconi, left, and Nikola Tesla both claimed to be the inventor of radio.|
People still argue over who invented the radio: Nikola Tesla or Guglielmo Marconi. Both camps have good arguments: Tesla lectured about radio technology first, but Marconi was the first to win a patent. But for either man to invent the radio, someone first had to discover the natural phenomenon of radio waves and invent ways to transmit them.
Radio is a descendant of two earlier, but related, technologies: the telegraph and the telephone. Mahlon Loomis demonstrated "wireless telegraphy" in 1866. Alexander Graham Bell and Elisha Gray independently invented devices in the 1876 that could transmit voices via electric wire.
Hertz and Maxwell: Discovering the wave
In the late 1860s, a Scottish physicist James Clerk Maxwell developed theories and equations describing electromagnetism. Maxwell thought that electromagnetic radiation, a form of energy, moves in waves that behave a lot like the mechanical waves we see in the ocean. Each wave has a wavelength, an amplitude and a frequency. But unlike mechanical waves, which require a medium such as air to move through, electromagnetic waves can move through a vacuum. Electromagnetic waves also self-propagate: an electric field creates a magnetic field, which creates an electric field and so on. And all electromagnetic waves move at the speed of light in a vacuum. In fact, visible light is one sliver of the electromagnetic spectrum that includes X-rays, microwaves and radio waves.
Maxwell died of stomach cancer in 1879 at the age of 48. Not all inventors thought his theories were useful. However, his work piqued the interest of a young German physicist named Heinrich Hertz. In 1888, Hertz produced and measured radio waves in his laboratory, adding proof to Maxwell's ideas. Hertz died in 1894 at the age of 36 after a long illness. The unit for frequency is named in his honor.
Once Hertz discovered how to make and detect radio waves, it didn't take long for engineers to invent systems to send and receive information through radio waves. Today you may tune into FM or AM radio. In an FM (frequency modulation) signal, the frequency of the radio wave is varied to convey the information that your radio will convert to sound, a mechanical wave in air. In AM radio (amplitude modulation), changes in the amplitude carry information to create the audio.
Tesla was born in 1856 to ethnically Serbian parents in what is now Croatia. After college and a job in Paris, Tesla moved to the United States to work for Thomas Edison, who would become his professional rival. Among his many scientific contributions, Tesla invented the Tesla coil, a device that could send and receive radio waves. He championed the development of alternating current (AC) power that is still used to light electrical grids today.
In 1893, Tesla held a lecture about using electromagnetic radiation for wireless signaling at Philadelphia's Franklin Institute. He then demonstrated the idea with a radio-controlled boat in Madison Square Garden, in New York City. He applied for several U.S. patents on the technology in 1897 and won them in 1900.
Marconi was the son of Italian landowner and high society Irish mother. He built a laboratory on his father's country estate in 1895, and began sending wireless signal over a distance of several miles. Marconi won the first patent for “wireless telegraphy" in 1896 and went on to found the successful Wireless Telegraph & Signal Company (later re-named Marconi's Wireless Telegraph Company).In 1901, he sent the first trans-Atlantic telegraph. Meanwhile, he got financial support from Thomas Edison and Andrew Carnegie.
In 1904, the U.S. Patent Office revoked Tesla's patent for the invention of radio and gave it to Marconi. The decision was one of several professional setbacks in his career, including a fire that destroyed his laboratory and financial losses. Adding insult to injury, Marconi won the Nobel Prize in physics in 1909 with Karl Braun for his work in radio. In 1915, Tesla sued Marconi for patent infringement but failed to win the lawsuit.
Marconi spent his career improving radio technology and transmitting signals over ever greater distances. He foretold of the principles of radar technology in 1922 and demonstrated microwave radio beacons for ship navigation in 1932. Marconi spent many years living and traveling on his yacht "Elettra" while continuing his work in radio. He died in Rome in 1937.
Ironically, Marconi's company ended up suing the U.S. government for patent infringement in 1943. Rather than take up the issue, the U.S. Supreme Court restored Tesla's patent for the invention of radio. Unfortunately, Tesla had died months before.
Radio changes lives, saves lives
Some of radio's earliest adopters were at sea. With instant, wireless communication, sea travel became much safer. In 1899, a wireless distress signal saved a stranded ship for the first time in history, according to IEEE Spectrum.
Many credited Marconi's technology for saving the remaining survivors of the Titanic. Records from that night in 1912 show the Titanic's crew first sent out Marconi's adopted CQD distress calls and later tried SOS. The Carpathia was 58 miles away when the Titanic hit ice, but received the distress signals and reached survivors just hours after the Titanic sank. Tragically, the operator on the closest ship to them, the Californian, had just turned off the radio for the night. The Titanic catastrophe prompted the International Radiotelegraph Convention to adopt one international maritime distress call, SOS, and around-the-clock staffing of wireless stations on ships.
For most people in the early 20th century, radio meant access to news and entertainment. The first radio broadcasting station, KDKA in Pittsburgh, Pa., started in 1919. Soon radio dramas, news, and music hours boomed in popularity. By the end of World War II, 95 percent of American homes had a radio. Television surpassed radio dramas popularity by the late 1950s, but radio has maintained its place as an important news medium.
Worldwide, radio reaches more than 95 percent of the population and is a key communication tool in developing countries. Local commercial radio listenership grew in Sub-Saharan Africa by 360 percent from 2000 to 2006 according to United Nations Educational, Scientific and Cultural Organization (UNESCO). Traditional radio programming is also gaining strength online. According to the Pew Research Center, the proportion of people who use or own a traditional radio dropped from 96 to 93 percent from 2010 to 2011. However, one third of Americans now stream radio programs and are listening longer: up from 6 hours per week in 2008 to nearly 10 hours a week in 2011.