Beginnings
Of the many technological breakthroughs that have shaped post-industrial society, radio and its related technologies have proven to be among the most important and far-reaching. The discovery that electromagnetic waves could be generated, transmitted over distances and picked up by a remote receiver revolutionised communications in a manner comparable with the invention of printing. The Italian inventor and entrepreneur Guillermo Marconi picked up the idea in the late 1890s. His experiments eventually led to the pioneering patents for the process of wireless telegraphy and he and his staff invented the systems that allowed the transmission of Morse code (telegraphy) over the airwaves (wireless).

Since radio needed no wires or cables, it was potentially of great value for areas where it would have been difficult or uneconomic to lay telegraph lines, such as across water. But while Marconi's early experiments excited great interest, radio's practical value was severely limited. In 1897 the greatest distance Marconi could transmit was only 9 miles. So he began an all-out effort to build up his business and develop the technology to span far greater distances. As Marconi's radios became more powerful, the invention was quickly put to practical use and as early as 1900 the first ship-borne radio had been installed on a German vessel.

Marconi finally demonstrated the feasibility of long-distance radiotelegraphy when he made the first readable trans-Atlantic transmission on 5 December 1902. But another major advance in technology was needed before radio could move into the next phase of development. The problem was that Marconi's radio could only transmit pulses, audible as faint clicks or beeps in the operator's headphones. The invention that changed all that was an unexpected spin-off from the light bulb.

In the late 1800s, Thomas Edison discovered that, besides the current travelling along the filament in his prototype electric lamps, there was a tiny anomalous electric current that was leaking across, through the vacuum, between the two poles. He began to explore the phenomenon and soon found that if he removed the filament, and substituted a plate for one of the two poles, this small current could be made to flow from the pole to the plate in one direction, but not the other. He had discovered the first electric valve. Marconi's scientific adviser Professor J. Ambrose Fleming visited Edison in 1889 and was given some of the experimental bulbs, but neither he nor Edison could see any immediate application for it, and on his return to England Fleming put the globes away and forgot about them.

Fate now stepped in. By early 1904 Fleming was going deaf, and he found the weak output from the Marconi headphones increasingly hard to hear. He started looking for a way to create a visual output for the signal, and this reminded him about the Edison tubes, so he fished them out of the cupboard and began to experiment with them. He set up a spark generator with an oscillating current, and discovered that the spark would induce a current in the primitive valve when it was placed near the spark generator. He instantly realised that the valve could be used could be used "rectify" these oscillating signals. He began to improve the performance and later in the year unveiled what he called the "Thermionic Tube" -- the world's first diode valve.

Although development was still slow and the technology very basic, within a decade two events would publicly demonstrate the potential of the new technology in dramatic fashion. The first, in 1910, was the capture of the notorious British murderer Dr Crippen. En route to Canada, the captain of the ship on which Crippen was escaping recognised him and he alerted Scotland Yard by radio, enabling the fugitive to be apprehended on arrival. The second was the tragic sinking of the Titanic in 1912, when the stricken ship sent out distress signals over the air for the first time, enabling nearby ships equipped with radio to come to the rescue of survivors within hours.

Marconi is generally credited as the "inventor" of radio, and this is basically true, but Marconi's radio system was extremely limited and his radio sets were primitive in the extreme. The crude "transmitters" were simple spark generators, firing a charge across a gap between two poles to generate the radio pulse. The signals they produced were so weak that sunlight washed them out during daylight hours, and they required enormous and expensive aerial arrays to be detected. The iron-filing or magnetic receivers were cruder still, requiring tight earphones and quiet rooms to catch the faint Morse code signals that were all the early wireless was capable of transmitting. This was of course its major weakness. By the early 1900s Bell's invention of the telephone had revolutionised telegraphy, introducing a means of carrying sounds and voices across the telegraph wires. The subsequent success of telephone-based local entertainment "networks" in the US in the early 1900s exerted further pressure on Marconi to develop a way of extending telephonic capability to radio.

From Telegraphy to Telephony
The true "founding fathers" of radio were two remarkable American scientists, Dr Lee De Forest (1873-1961) and Edwin H. Armstrong (1890-1954). It was their brilliant inventions that made possible radio and TV broadcasting, as we know them today.

During his lifetime, Lee de Forest received over 180 patents, but he is best known for his contributions and improvements to the invention that formed the basis of all electronics -- the vacuum tube valve. In 1906 de Forest modified Fleming's diode by adding a third element. He placed a charged wire grid between the anode and the cathode and he found that by applying a current to the grid, he could control and amplify the current flow. He called his device the "Audion". Patented in January 1907, De Forest's Audion, the first triode valve, was mainly used as a detector of radio signals.

But the Audion was not developed right away, partly because De Forest did not immediately grasp its potential, and partly because of its inherent technical limitations. Amateur and professional experimenters picked it up, but they soon discovered its shortcomings. Audion-based devices could not amplify weak signals at the receiver, nor could they provide stronger, more reliable power for the transmitter. Moreover, the manufacture of vacuum tubes was still in its infancy and the Audion tubes that were available were crude, weak and notoriously unreliable. De Forest returned to experimenting with arc transmitters, but by 1916 research conducted by the US Navy and AT&T made him realise that he had crucially overlooked the potential of his Audion valve to act as a transmitter. By then, manufacturing improvements had made the vacuum valve far more reliable, so in 1916 he went back to work on the Audion, creating some of the first valve transmitters and making pioneering broadcasts in New York.

The adaptation of the Audion triode valve for use as a transmitter was the breakthrough that made wireless telephony possible. Now, very weak signals could be amplified to a more useable level, and the signal output could be controlled and varied in a very precise way by the grid element. It immediately became obvious that, for example, by feeding the weak electrical signal from a microphone (e.g. a telephone mouthpiece) into the triode valve, voice signals could at last be amplified, transmitted and received via radio.

However, it would not be plain sailing for the main players -- De Forest's 1906 alterations to the Thermionic Valve came to Fleming's attention almost immediately, and this triggered a bitter, protracted and vastly expensive legal battle over the rights to the patents.


The Boy Genius
If there is any one person who can claim to be "the father of radio", it is Edwin Armstrong. He decided as a child that he was going to be an inventor. Inspired by Marconi and captivated by the new radio technology, he methodically set about exploring and studying it. As a teenager he built his own radio sets from scratch and he even constructed a 125-foot antenna on the lawn of his parents' house in Yonkers. Although a brilliant inventor, De Forest did not fully comprehend the principles behind the triode. Armstrong had no such limitations, and he devoted considerable time to studying De Forests's newly-invented valve, seeking to improve its performance. In 1912, while a 22-year-old Columbia University freshman, he invented a circuit that fed some of the signal output from the plate back into the grid. He found that this dramatically boosted the strength of an incoming signal. Testing the concept in his turret room in Yonkers, he began picking up distant stations so loudly that they could be heard without earphones.

Armstrong's invention, the Regenerating Circuit, was a "double whammy". It was able to amplify the weak signals from distant transmitters to unprecedented levels but just as importantly, Armstrong found that when the feedback was pushed to a high level the tube produced rapid electromagnetic oscillations, acting as a transmitter and emitting radio waves. Thus, a single circuit yielded not only the first radio amplifier but also the key to the continuous-sine-wave transmitter that is still at the heart of all radio operations. It revolutionised electronics and without it there could have been no broadcasting industry, no public address systems (and no electric guitars)!

The First World War
With the breakout of the War (1914-1918) wireless telegraphy around the world immediately came under the control of national governments because of its immense security and strategic importance. De Forest's triode valve now enabled the transmission of voice signals and Armstrong's subsequent invention of the Regenerating Circuit made reliable long-distance radiotelephony a reality. Up until then radio had only been seen in terms of telegraphy, and its potential was seen as being primarily for point-to-point communication. Two further wartime developments would change the face of radio forever.

In New York in 1916, a young employee of the Marconi Company listened avidly to Lee De Forest's experimental broadcasts. Inspired by what he heard, the man had a vision for the potential use of the new medium, and he promptly set his ideas down in an historic memo, which he sent to his boss around November 1916. In it he wrote: 'I have a plan that would make radio a household utility ... the idea is to bring music into the house by wireless".

The young visionary was David Sarnoff. Born in Uzlian, Russia, Sarnoff travelled steerage to New York nine years later with his family. Speaking no English, he educated himself and helped support his family by selling newspapers and other small jobs. At 15 he bought a telegraph key, taught himself Morse code and, after being hired as an office boy for the Marconi Wireless Telegraph Co. of America, became a junior operator in 1908.

Sarnoff's first "break" was a classic case of being in the right place at the right time. On April 14, 1912, he was working at the Marconi station atop Wanamaker's department store in New York when he picked up a message relayed from ships at sea: "S.S. Titanic ran into iceberg, sinking fast." For the next 72 hours, the story goes, he remained at his post, giving the world the first authentic news of the disaster. The Titanic episode set Sarnoff thinking, but the real spark was De Forest's test broadcasts in 1916. Hearing these, Sarnoff realised the potential for radio to become a means to distribute entertainment and information from one point to many -- broadcasting -- a means of mass communication, rather than a person-to-person relay. Here again, Sarnoff was fortunate in being "Johnny On The Spot" -- within a few months of De Forests test broadcasts, the US had entered World War 1, the US War Department took control of all radio activity, and all private transmission and radio listening was banned.

World War I broke out before Armstrong was able to commercially develop his Regnerating Circuit, and when the US entered the war in 1917 he was conscripted to the US Army Signal Corps. He was sent to France to design equipment for detecting shortwave enemy communications, and this led to his second major invention. Drawing on his childhood experiments, Armstrong adapted an early -- but little used -- wireless technique called "heterodyning", and designed a complex eight-tube receiver. In tests from the Eiffel Tower it amplified weak signals to levels far beyond anything previously achieved. He dubbed his invention the Superheterodyne Circuit, and although it detected no secret enemy transmissions, it became the basic receiver circuit for broadcasting and the backbone of the industry. Almost a century later, miniaturised versions of the same circuit can still be found in 98 percent of all radio and television receivers!

Armstrong continued his research into the problems of static and interference, and in 1933 unveiled perhaps his greatest invention - FM radio broadcasting. He spent years trying to establish FM, but he was pitted against conservative regulators (it took him seven years to get a permit from the FCC for his first FM station) and the might of the huge, entrenched and unscrupulous American radio industry, led by his nemesis, David Sarnoff, the domineering head of RCA. Armstrong's inventions made him a millionaire, but much of his later life was taken up with costly and bitter battles --particularly with Sarnoff and RCA -- over the rights to his patents. Finally, worn down by the protracted battles against regulators and the industry, and facing financial ruin, he committed suicide in 1954. His work was eventually vindicated and by the late 60s FM was recognised around the world as the superior form of transmission. Today it is the most widely used medium, and the basis of all radio TV, microwave and satellite networks.

"Empire of the Air" - The Birth of Broadcasting
Sarnoff's relentless drive and ability propelled him quickly through the ranks at Marconi. His idea for a "radio music box" came at a time when radio was mainly used in shipping and by amateur wireless enthusiasts. He believed his device would make radio into a "household utility" like the piano or phonograph. In 1916 his vision was way ahead of current technology and it was considered commercial folly. But Sarnoff would soon have the opportunity to bring his vision to fruition.

In 1919, the huge General Electric Company absorbed all of Marconi's American interests and formed the Radio Corporation of America -- RCA. Armstrong's invention of the Superheterodyne Circuit meant that the transmission of powerful, long-distance broadcasts, with complex audio signals like voices and music, was now feasible. But Sarnoff knew that for his vision to succeed, RCA needed become a "vertically integrated" business -- the same strategy that had made companies like Standard Oil and Ford the dominant players in their respective industries. Sarnoff knew that for RCA to sell radios, it also had to provide programming -- music, news, sports, entertainment -- and it had to have the broadcasting facilities to transmit them.

On July 2, 1921, RCA arranged the broadcast of the Jack Dempsey-Georges Carpentier prize fight. It was was a watershed event and the audience reaction to the event conclusively proved the viability of Sarnoff's concept. RCA geared up to follow through, and within three years Sarnoff's "radio music box" -- now called the "Radiola" -- had become a runaway success, and in spite of its whopping $75 price tag (the equivalent of perhaps $1000 today) sales of the new radio receivers had passed $80 million by 1925. Sarnoff's career took off with it, and he advanced rapidly to become one of the senior executives at RCA. With the power and resources of the huge company behind him, he could now begin to enact the rest of his vision -- to create simultaneous nationwide entertainment broadcasts by stringing together hundreds of stations to form a radio "network".

By 1926, Sarnoff was general manager of RCA; by 1930 he was president and RCA was the biggest broadcaster in the world, manufacturing its own radios, producing its own programmes and broadcasting them across America through its vast network of radio stations. The inventions of Fleming, De Forest and Armstrong and the entrepreneurial vision of Sarnoff created a new medium of communication that soon spanned the entire globe.