Guglielmo Marconi
inventor and engineer Guglielmo Marconi developed, demonstrated and marketed the first successful long-distance wireless telegraph and in 1901 broadcast the first transatlantic radio signal. His company’s Marconi radios ended the isolation of ocean travel and saved hundreds of lives, including all of the surviving passengers from the sinking Titanic. In 1909 he shared the Nobel Prize in Physics for his radio work. He is generally credited with the invention of radio the controversy with Tesla not withstanding. Born:April 25, 1874, Bologna, Italy Died:July 20, 1937, Rome, Italy |
The Marconi Story
Early in the 19th century, Danish Physicist Hans Christian Oersted demonstrated that an electric current could produce a magnetic force. Then Michael Faraday, an English physicist, demonstrated electromagnetic induction. The Scott James Clerk Maxwell, professor of experimental physics at Cambridge, in 1864 proved mathematically that an electrical disturbance could propagate an effect at a considerable distance from the point at which it occurred and predicted that electromagnetic energy could travel outward from a source as waves moving at the speed of light.
At the time of Maxwell’s prediction there were no known means of creating or detecting the presence of electromagnetic waves in space. It was not until about 1888 that Maxwell’s theory was definitively proven experimentally by the German physicist Heinrich Hertz.
Now: Enter the Italian: Guglielmo Giovanni Maria Marconi
While on holiday in 1894 Marconi read about the experiments that Hertz did in the 1880s. After reading the articles about Hertzian waves Marconi thought these waves could be used for wireless communications. Marconi was 20 years old at the time. What 20 year old on summer holiday would read technical journals? Well I guess that is what makes a man like Marconi different.
Marconi set about experimenting with the new phenomena of electromagnetic waves. Marconi built a lab in the attic of the family home at the Villa Griffone in Pontecchio. Marconi expanded on Hertz's experiments building a transmitter and receiver that he first demonstrated to his mother by transmitting an electromagnetic waves across the lab ringing a bell at the receiver. He used a simple induction coil with a metal sheet aerial.
Continuing to experiment Marconi found that the range of signaling could be increased further by replacing the original sheet aerial with a vertical aerial with a metal plate or cylinder at the top of a pole connected to a similar plate on the ground. Marconi had just invented the earthed vertical aerial. This basic aerial is wide use today by broadcast radio stations world wide. By using the vertical aerial he was able to increase range of signaling to about 2.4 km , enough to convince Marconi of the potential of this new system of communication. During this period he also conducted simple experiments with reflectors around the aerial to concentrate the radiated electrical energy into a crude beam instead of spreading it in all directions. Hertz had done similar experiments in his laboratory.
Marconi continued to experiment and modify his crude apparatuses: an induction coil for increasing voltages, with a spark discharger controlled by a Morse key at the sending end. For a receiver he used a simple coherer, a device for detecting Hertzian waves invented by the French physicist and inventor Edouard Branley in 1890.
Branley’s Coherer consisted of a glass tube partially filled with iron filings and plugged with corks through which wire electrodes had been forced. In operation, the iron filings cohered when a strong radio signal was impressed across the electrodes. Branley did not use his instrument for the reception of radio waves, but he did find that the Coherer had to be tapped manually to decohere the filings in order to return the unit to a high-resistance condition.
Marconi took the crude Coherer Branley had designed and made improvements. He replaced the corks with silver plugs. And by using a mixture of silver and nickel filings in place of iron filings and evacuating the air from the tube, Marconi succeeded in producing a device many times more sensitive than the original Coherer. Marconi also added a tapper to automatically de-coher the filings.
Marconi attained results that can only be described as spectacular. Signals of from 2 to 14 Km were observed almost immediately, and by early 1901 the range had been extended to over 300 Km. Building upon this success Marconi continued to experiment and develop transmitter and receiver components for what would become the new industry of wireless telegraphy and eventually spawn many other industries such as Radio and Television broadcasting. Progress was rapid.
But At the time scientists thought that because electromagnetic waves travel in straight lines that their useful range was limited to line of sight only. This after all was the settled science of the day. Marconi had a healthy disrespect for settled science, he thought differently, he was a tinkerer, an experimenter. In spite of the opinions expressed by some distinguished physicists mathematicians that the curvature of the Earth would limit practical transmission by means of electric waves to a distance of roughly 300Km (161–322 km) , Marconi decided to go with his gut regardless and attempt a trans-Atlantic transmission.
Marconi had set up a specially designed wireless receiver at St. Johns Newfoundland, using a coherer to detect radio waves, balloons and kites were to lift the aerial as high as possible. The signal sent was the letter S in Morse code from Poldhu, Cornwall, in England.
In the late afternoon of December 12, 1901 Marconi succeed in receiving at St. John’s, Newfoundland, signals transmitted from Poldhu in Cornwall, England. This achievement created an immediate sensation, and, though much remained to be learned about how radio waves propagate around the Earth and through the atmosphere, it was the starting point for the vast development of radio communications, broadcasting, and navigation services that took place in the next 50 years, and in which Marconi himself played an important role.
During a voyage on the U.S. liner Philadelphia in 1902, Marconi received messages from distances of 1,125 km by day and 3,200 km by night. He thus was the first to discover that, because some radio waves travel by reflecting from the upper regions of the atmosphere, transmission conditions are sometimes more favourable at night than during the day. This is due to the fact that the skyward propagation of the waves is limited in the daytime by absorption in the lower atmosphere, which becomes ionized—and is to some extent electrically conducting—under the influence of sunlight. During darkness the lower layer of the atmosphere is not ionized and the radio waves are able to reflect from a higher layer in the upper atmosphere enabling longer distance transmission. The actual physics of this would not be understood for some time.
During the next three years, Marconi developed and patented the horizontal directional aerial and made other improvements to the efficiency of his communication aparatus. In 1910 he received messages at Buenos Aires from Clifden in Ireland over a distance of approximately 9,650 km, using a wavelength of about 8,000 metres. Two years later Marconi introduced further innovations that so improved transmission and reception over long distances. The increased efficiency allowed Marconi to send the first radio message between England to Australia in September 1918.
About the first trans-atlantic transmission Marconi later wrote:
Shortly before midday I placed the single earphone to my ear and started listening. The receiver on the table before me was very crude -- a few coils and condensers and a coherer -- no valves, no amplifiers, not even a crystal. But I was at last on the point of putting the correctness of all my beliefs to test. The answer came at 12: 30 when I heard, faintly but distinctly, pip-pip-pip. I handed the phone to Kemp: "Can you hear anything?" I asked. "Yes," he said. "The letter S." He could hear it. I knew then that all my anticipations had been justified. The electric waves sent out into space from Poldhu had traversed the Atlantic -- the distance, enormous as it seemed then, of 1,700 miles -- unimpeded by the curvature of the earth. The result meant much more to me than the mere successful realization of an experiment. As Sir Oliver Lodge has stated, it was an epoch in history. I now felt for the first time absolutely certain that the day would come when mankind would be able to send messages without wires not only across the Atlantic but between the farthermost ends of the earth.
The first commercial uses of wireless telegraphy were in providing ship to shore and ship to ship communications. It is hard to imagine now but in those days when a ship went to sea there was no way to communicate with it. If the ship got into trouble and was sinking there was no way for them to signal for help. That all changed with Marconi. The new wireless telegraphy systems were being installed and operated aboard ships by the newly formed Marconi Wireless Co. The Marconi company was instrumental in numerous maritime rescues as both the radio equipment and the radio operators were contracted to the shipping lines by the Marconi company. The incident that made Marconi a household name, if he wasn’t already, was the sinking of the Titanic.
On the night of April 14, 1912 the Titanic struck an iceberg in the North Atlantic. For the next two hours Marconi radio operator Jack Phillips and assistant operator Harold Bride sent out a stream of CQD distress signals. CQD was the Marconi companies distress signal. The SOS had just been approved as the new international distress standard. Not knowing that the Cunard liner Carpathia had picked up their distress call earlier and was already on its way, Harold Bride turned to Phillips and said, Send the SOS. It’s the new distress signal, and it may be our last chance to send it. Thus the titanic disaster saw the first use of the SOS signal.
As dawn broke Carpathia arrived at the grid reference transmitted by Phillips. Two hours earlier the Titanic had gone under. Carpathia’s crew rescued all the survivors they could find, retrieved 300 bodies from the icy water, and then steamed for New York. According to the postmaster-general of Britain regarding the Titanic disaster: "Those who have been saved, have been saved through one man, Mr. Marconi ... and his marvelous invention."
Early in the 19th century, Danish Physicist Hans Christian Oersted demonstrated that an electric current could produce a magnetic force. Then Michael Faraday, an English physicist, demonstrated electromagnetic induction. The Scott James Clerk Maxwell, professor of experimental physics at Cambridge, in 1864 proved mathematically that an electrical disturbance could propagate an effect at a considerable distance from the point at which it occurred and predicted that electromagnetic energy could travel outward from a source as waves moving at the speed of light.
At the time of Maxwell’s prediction there were no known means of creating or detecting the presence of electromagnetic waves in space. It was not until about 1888 that Maxwell’s theory was definitively proven experimentally by the German physicist Heinrich Hertz.
Now: Enter the Italian: Guglielmo Giovanni Maria Marconi
While on holiday in 1894 Marconi read about the experiments that Hertz did in the 1880s. After reading the articles about Hertzian waves Marconi thought these waves could be used for wireless communications. Marconi was 20 years old at the time. What 20 year old on summer holiday would read technical journals? Well I guess that is what makes a man like Marconi different.
Marconi set about experimenting with the new phenomena of electromagnetic waves. Marconi built a lab in the attic of the family home at the Villa Griffone in Pontecchio. Marconi expanded on Hertz's experiments building a transmitter and receiver that he first demonstrated to his mother by transmitting an electromagnetic waves across the lab ringing a bell at the receiver. He used a simple induction coil with a metal sheet aerial.
Continuing to experiment Marconi found that the range of signaling could be increased further by replacing the original sheet aerial with a vertical aerial with a metal plate or cylinder at the top of a pole connected to a similar plate on the ground. Marconi had just invented the earthed vertical aerial. This basic aerial is wide use today by broadcast radio stations world wide. By using the vertical aerial he was able to increase range of signaling to about 2.4 km , enough to convince Marconi of the potential of this new system of communication. During this period he also conducted simple experiments with reflectors around the aerial to concentrate the radiated electrical energy into a crude beam instead of spreading it in all directions. Hertz had done similar experiments in his laboratory.
Marconi continued to experiment and modify his crude apparatuses: an induction coil for increasing voltages, with a spark discharger controlled by a Morse key at the sending end. For a receiver he used a simple coherer, a device for detecting Hertzian waves invented by the French physicist and inventor Edouard Branley in 1890.
Branley’s Coherer consisted of a glass tube partially filled with iron filings and plugged with corks through which wire electrodes had been forced. In operation, the iron filings cohered when a strong radio signal was impressed across the electrodes. Branley did not use his instrument for the reception of radio waves, but he did find that the Coherer had to be tapped manually to decohere the filings in order to return the unit to a high-resistance condition.
Marconi took the crude Coherer Branley had designed and made improvements. He replaced the corks with silver plugs. And by using a mixture of silver and nickel filings in place of iron filings and evacuating the air from the tube, Marconi succeeded in producing a device many times more sensitive than the original Coherer. Marconi also added a tapper to automatically de-coher the filings.
Marconi attained results that can only be described as spectacular. Signals of from 2 to 14 Km were observed almost immediately, and by early 1901 the range had been extended to over 300 Km. Building upon this success Marconi continued to experiment and develop transmitter and receiver components for what would become the new industry of wireless telegraphy and eventually spawn many other industries such as Radio and Television broadcasting. Progress was rapid.
But At the time scientists thought that because electromagnetic waves travel in straight lines that their useful range was limited to line of sight only. This after all was the settled science of the day. Marconi had a healthy disrespect for settled science, he thought differently, he was a tinkerer, an experimenter. In spite of the opinions expressed by some distinguished physicists mathematicians that the curvature of the Earth would limit practical transmission by means of electric waves to a distance of roughly 300Km (161–322 km) , Marconi decided to go with his gut regardless and attempt a trans-Atlantic transmission.
Marconi had set up a specially designed wireless receiver at St. Johns Newfoundland, using a coherer to detect radio waves, balloons and kites were to lift the aerial as high as possible. The signal sent was the letter S in Morse code from Poldhu, Cornwall, in England.
In the late afternoon of December 12, 1901 Marconi succeed in receiving at St. John’s, Newfoundland, signals transmitted from Poldhu in Cornwall, England. This achievement created an immediate sensation, and, though much remained to be learned about how radio waves propagate around the Earth and through the atmosphere, it was the starting point for the vast development of radio communications, broadcasting, and navigation services that took place in the next 50 years, and in which Marconi himself played an important role.
During a voyage on the U.S. liner Philadelphia in 1902, Marconi received messages from distances of 1,125 km by day and 3,200 km by night. He thus was the first to discover that, because some radio waves travel by reflecting from the upper regions of the atmosphere, transmission conditions are sometimes more favourable at night than during the day. This is due to the fact that the skyward propagation of the waves is limited in the daytime by absorption in the lower atmosphere, which becomes ionized—and is to some extent electrically conducting—under the influence of sunlight. During darkness the lower layer of the atmosphere is not ionized and the radio waves are able to reflect from a higher layer in the upper atmosphere enabling longer distance transmission. The actual physics of this would not be understood for some time.
During the next three years, Marconi developed and patented the horizontal directional aerial and made other improvements to the efficiency of his communication aparatus. In 1910 he received messages at Buenos Aires from Clifden in Ireland over a distance of approximately 9,650 km, using a wavelength of about 8,000 metres. Two years later Marconi introduced further innovations that so improved transmission and reception over long distances. The increased efficiency allowed Marconi to send the first radio message between England to Australia in September 1918.
About the first trans-atlantic transmission Marconi later wrote:
Shortly before midday I placed the single earphone to my ear and started listening. The receiver on the table before me was very crude -- a few coils and condensers and a coherer -- no valves, no amplifiers, not even a crystal. But I was at last on the point of putting the correctness of all my beliefs to test. The answer came at 12: 30 when I heard, faintly but distinctly, pip-pip-pip. I handed the phone to Kemp: "Can you hear anything?" I asked. "Yes," he said. "The letter S." He could hear it. I knew then that all my anticipations had been justified. The electric waves sent out into space from Poldhu had traversed the Atlantic -- the distance, enormous as it seemed then, of 1,700 miles -- unimpeded by the curvature of the earth. The result meant much more to me than the mere successful realization of an experiment. As Sir Oliver Lodge has stated, it was an epoch in history. I now felt for the first time absolutely certain that the day would come when mankind would be able to send messages without wires not only across the Atlantic but between the farthermost ends of the earth.
The first commercial uses of wireless telegraphy were in providing ship to shore and ship to ship communications. It is hard to imagine now but in those days when a ship went to sea there was no way to communicate with it. If the ship got into trouble and was sinking there was no way for them to signal for help. That all changed with Marconi. The new wireless telegraphy systems were being installed and operated aboard ships by the newly formed Marconi Wireless Co. The Marconi company was instrumental in numerous maritime rescues as both the radio equipment and the radio operators were contracted to the shipping lines by the Marconi company. The incident that made Marconi a household name, if he wasn’t already, was the sinking of the Titanic.
On the night of April 14, 1912 the Titanic struck an iceberg in the North Atlantic. For the next two hours Marconi radio operator Jack Phillips and assistant operator Harold Bride sent out a stream of CQD distress signals. CQD was the Marconi companies distress signal. The SOS had just been approved as the new international distress standard. Not knowing that the Cunard liner Carpathia had picked up their distress call earlier and was already on its way, Harold Bride turned to Phillips and said, Send the SOS. It’s the new distress signal, and it may be our last chance to send it. Thus the titanic disaster saw the first use of the SOS signal.
As dawn broke Carpathia arrived at the grid reference transmitted by Phillips. Two hours earlier the Titanic had gone under. Carpathia’s crew rescued all the survivors they could find, retrieved 300 bodies from the icy water, and then steamed for New York. According to the postmaster-general of Britain regarding the Titanic disaster: "Those who have been saved, have been saved through one man, Mr. Marconi ... and his marvelous invention."