In this era when wireless technology has reached almost all the fields and created a revolution in telecommunications, the information on invention of first wireless communication device is certainly inspiring. The invention of radio too emanated from the earlier dynamic inventions of telegraph and telephone. Wireless telegraphy was the juvenile stage from which evolved the rudiments of radio. The technologies of telephone and telegraph are so intertwined that one could not have been possible without the other.
Radio can be explained as an electronic appliance through which we listen to a content-music, story, information, news and other things. Radio waves which are a part of the electromagnetic spectrum have the ability to transmit speech, pictures, music and other types of data through air invisibly. Some other devices which also used electromagnetic waves apart from radio are microwaves, remote controlled toys, cordless phones, television broadcasts etc.
As said earlier, radio invention evolved gradually as other correlated inventions came to the fore. James Clerk Maxwell, a Scottish physicist in 1860s had come across radio waves and in 1886, Heinrich Rudolph Hertz, a German physicist also demonstrated that electric currents with varying and fast speed could be sent into space as radio waves just as the light and heat waves. But even before that Mahlon Loomis who was an American dentist had successfully displayed the experiment of wireless telegraphy. So as to display his invention, Loomis connected a meter to one kite and showed how the other kite moved because of this connection. This was the first ever demonstration of wireless aerial communication.
In 1895, an Italian inventor, Guglielmo Marconi, for the first time sent and received radio signal in Italy. He was the first to let everyone know the economical viability of radio transmission. In 1899, Marconi had flashed across the English Channel, the first wireless signal and in 1902 he sent ‘ S’ letter from England which was received in Newfoundland and is considered the first transatlantic radiotelegraph message which was successfully transmitted. At the same time Nikola Tesla and Nathan Stufflefield also had applied for wireless radio transmitters patent and in 1943 Supreme Court rejected Marconi’s patent and granted the credit of radio technology patent to Tesla.
In radio-telegraphy, the dot-dash message was sent through radio waves. Spark gap machines were the transmitters used for this purpose. It was one of the simplest ways of transmitting message from one point to another. The first radiotelegraph service was started on five Hawaiian Islands and by 1903; Wellfleet, Massachusetts station of Marconi had started sending greetings between President Theodore Roosevelt and King Edward VII. In 1910 an American-Europeon radiotelegraph service was opened by Marconi and in 1912 San Francisco was connected with Hawaii for the first time via transpacific radiotelegraph. But it was the Alexanderson high frequency alternator along with the De Forest tube which really helped in solving technical problems in radio transmissions and from then on the technology developed very fast.
After the earlier technical advancements in the field of radio waves, it was taken further by the development of a delicate and very efficient electromagnetic radiation detector which was invented by Lee Deforest. He is also credited with the invention of triode amplifier, Audion and space technology. This detector could amplify the radio frequency signal detected by the antenna much before they were applied to the detector. Due to this the weaker signals too were utilized. Lee Deforest used the word ‘radio’ for the first time and AM or amplitude modulated radio which made way for establishing multiple radio stations was invented by him.