Radio

Background

Radio waves, like light, are types of electromagnetic radiation. They both travel at the speed of light. The main factors of a radio wave that are used to transmit signals are the amplitude and the frequency of the waves.

History

The history of the development of the radio can be traced back to the early 1800s when English physicist Michael Faraday discovered that it was possible to create magnetic fields using electric currents. In 1864, James Clark Maxwell, building off Faraday's research, found that the effects of the magnetic fields could be measured at relatively large distances. This was confirmed by Heinrich Hertz in 1888 when he created a device that wirelessly sent a spark from one end of the machine to the other end about 5 feet away. Hertz also found that radio waves travel in straight lines and can be reflected by metal¹.

Marconi

Guglielmo Marconi was an Irish-Italian scientist who lived from 1874 to 1937. He is most well-known for his inventions and research on radio technology, for which he got a Nobel Prize for Physics in 1909. He started experimenting with radio waves in 1894, where, following Hertz's discoveries, he created an improved version of Hertz's machine that could send a spark across a distance of 30 feet. Eventually, he could refine his methods to the point where he could send a signal for 1.5 miles.

In 1896, Marconi moved to London to work with the chief engineer at the post office, filing his first patent that same year.

In 1900, Marconi filed patent 7777 in England, titled "Improvements in Apparatus for Wireless Telegraphy." As the title suggests, this patent mostly built off of another patent and described a machine that could transmit wireless signals more efficiently and effectively².

Timeline

1897 - Built a wireless telegraph system in Italy that could communicate with warships 12 miles away
1899 - Built a system between England and France (31 miles)
1899 - Was able to communicate with British warships 75 miles away
1899 - America's Cup (Yacht Race)

Two ships installed a Marconi radio machine to transmit information about the race back to New York City.
One of the first sports broadcasts³

1901 - Sent the letter ‘s’ over wireless telegraph over a distance of 2,000mi
1918 - Marconi long-wave station in Wales sends a signal to Australia (over 11,000 miles)
1919 - Marconi engineer sends a spoken radio message from Ireland to the US

The Audion

In 1904, Sir John Ambrose Fleming discovered that a positively charged electrode could carry a current through the empty space in a filament light bulb. This led to the invention of a diode, an electronic component that only allows current to flow in one direction. Also, diodes can rectify alternating current, turning it into a direct one. His diode could also 'detect' radio waves by translating the waves into direct-current pulses that corresponded with the Morse code message.

In 1906, Lee De Forest created the Audion, which controlled the flow of electrons between the filament and the positively charged electrode. This device was able to amplify incoming radio signals, which allowed for weaker frequencies to be utilized⁴.

Significance

The invention of the radio was a significant milestone in the history of human communication. Building off of the innovations of the telegram, radio took it one step further and permanently changed how humans communicate by allowing for wireless messages to be sent from anywhere, given they have a radio tower. There have also been many instances of the radio saving countless lives, the most famous being the sinking of the Titanic in 1912. Had there not been a Marconi Wireless Telegraph system aboard the ship, there would have been no way to get a signal out to alert other ships to their predicament, leaving no realistic option for survival⁵.