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E/M Waves
Maxwell proved the existence of electromagnetic waves. He proved it mathematically, and published his findings in multiiple papers. Much of his work was done while he was at Kings College London. -
Proof of Radio Waves
Heinrich Hertz proves the physical existence of radio waves that Maxwell proved mathematically. His transmitter consisted of a simple spark gap across an induction coil with a loop of wire to act as an antenna. The reciever had a smaller gap in a loop the same size as the transmitter. He was credited with discovery of this and what was originally called Hertzian waves. -
First Radio Wave
Guglielmo Marconi was in St. John’s, Newfoundland when he recieved the first transatlantic radio wave. The radio wave was sent from Cornwall, England some 2,000 miles away.The radio wave had been in morse code. In order to send a code wave back Marconi's engineers put a copper wire on a kite and sent it into the air. Marconi made a booming business off of this. -
Fleming invents the vaccumm diode
Sir John Fleming invented the two-electrode radio rectifier, or vaccumm diode. Fleming calls it an oscillation valve. He based it on Edison's lightbulbs, the valve reliably detects radio waves. -
The Audion
American entrepreneur Lee De Forest expands on Fleming's invention. He puts a 3rd wire, or grid, into a vaccumm tube creating a sensitive reciever. Forest goes on to call this the "Audion." Later on he finds out that by feeding the output back into it's grid and learns that by doing this he can transmit signals. -
Radio Signal Amplifier
Engineer student Edwin Howard Armstrong devises a regenerative circuit for the triode that amplifies radio signals By pushing the highest amplification, he discovers the key to continuous-wave transmission. This becomes the basis of amplitude modulation(AM) radio. -
Invention of the Superhet
Armstrong developed a receiver where the incoming signal was converted down to a fixed intermediate frequency. Now it could be satisfactorily amplified and filtered. At first the idea wasn't really accepted because the war just ended. Another reason they weren't that popular is because superhet receivers were very expensive because of the numbers of valves they used. -
FM Radio
Edwin Armstrong creates the frequency modulation(FM) radio. It was used as a solution to the static interference problem that was on the AM radio transmissions. Armstrong just changed the frequency that the radio signals were transmitted on. But it wasn't for several years that the FM recievers came on the market. -
Halloween Special
In 1938 Orson Welles directed a Halloween special on a broadcast about "The War of the Worlds." It was a 60 minute live broadcast presented mostly as a series of news bulletins. Most listeners were frightened and believed there really was a Martian invasion in progress. After all the commotion was over Welles still met with fame. -
Geostationary Satellites
Author Arthur Clarke wrote a historic book in "Wireless World" describing a system that used satellites in geostationary orbit. Signals would be transmitted up to the satellite that would rebroadcast them back to the earth. Clarke calculated that only three satellites would be required to cover around the globe. His idea was revolutionary, and it took many years before the technology was available for it to be implemented. -
Transistor
After the invention of the transistor, it became the most popular electronic communication device in history. Billions were made during the 1960's and 1970's. They were pocket-sized and created a change in popular music listening habits. People could listen to music anywhere they went. -
All-Transistor Radio
Texas instruments had designed and built a prototype, then they looked for an esatblished radio manufacturer to develop and market a radio using transistors. It was called the TR-1. It has 4 transistors in it. 1 acts as a combination mixer-oscillator, 1 as an audio amplifier, and 2 as intermediate-frequency amplifiers. 1 year after the release of the TR-1, sales hit the 100,000 mark.
