Edited by Gerald Boerner
Today we take radio broadcasts as a given. We get sporting events, political rallies, music, and a variety of talk programs. But it took technical developments and theoretical understanding by men like Guglielmo Marconi to define and harness the promise of wireless telegraphy.
As I was growing up, both of my Grandmothers had large, free-standing radio consoles on which we would hear regular shows like “The Lone Ranger,” “The Cisco Kid,” and “Hopalong Cassidy.” (These programs would eventually become TV shows!) But it was not always so.
It wasn’t until the early 1920s that the earliest radio sets were available. It took men like Marconi, Tesler, and many others to put the total picture. Marconi was the co-recipient, with Karl Ferdinand Braun, of the 1909 Nobel Prize in Physics. He also was awarded several patents (later disputed) for the technologies. His essential contribution was the understanding of using the electromagnetic spectrum to carry telegraphy signals. Without these contributions, we would not have today’s wireless networks (voice, data, LAN) or the mobile devices (computers or smartphones).
So, let’s get on with our exploration of these technologies… GLB
These Introductory Comments are copyrighted:
Copyright©2010 — Gerald Boerner — All Rights Reserved
[ 3881 Words ]
Quotations Related to WIRELESS
“Every day sees humanity more victorious in the struggle with space and time.”
— Guglielmo Marconi
“I am glad to have this opportunity of expressing my high appreciation of the honour extended to me many years ago by the Royal Swedish Academy of Science by enrolling me amongst its members.”
— Guglielmo Marconi
“As we have seen, the wireless and the airplane have made the world so small and nations so dependent on each other that the only alternative to war is the United States of the World.”
— John Boyd Orr
“You will also allow me to thank the Academy for inviting me to lecture in Stockholm, for its hospitality, and for the opportunity afforded me for admiring the charm of your people and the beauty of your country.”
— Guglielmo Marconi
“Thanks to the high standing which science has for so long attain and to the impartiality of the Nobel Prize Committee, the Nobel Prize for Physics is rightly considered everywhere as the highest reward within the reach of workers in Natural Philosophy.”
— Guglielmo Marconi
“And I was asked if I would come and help with the recovery of this great British company, Cable and Wireless, and I’m delighted to become part of the new and very talented management that have been brought in to that company as well.”
— Lord Robertson
“Integral to the orb is our low cost long-range wireless radio data system and a protocol that allows us to send this data over 90% of the US population every 15 minutes throughout the day.”
— David Rose
“Now that digital lifestyle devices, tablets, wireless phones, and other Internet appliances are beginning to come of age, we need to worry about presenting our content to these devices so that it is optimized for their display capabilities.”
— Mike Davidson
Guglielmo Marconi — The Invention of Radio (Wireless Telegraphy)
Guglielmo Marconi (1874– 1937) was an Italian inventor, best known for his development of a radio telegraph system, which served as the foundation for the establishment of numerous affiliated companies worldwide. He shared the 1909 Nobel Prize in Physics with Karl Ferdinand Braun "in recognition of their contributions to the development of wireless telegraphy" and was ennobled in 1924 as Marchese Marconi. Marconi’s law is named for him.
During his early years, Marconi had an interest in science and electricity. One of the scientific developments during this era came from Heinrich Hertz, who, beginning in 1888, demonstrated that one could produce and detect electromagnetic radiation—now generally known as "radio waves", at the time more commonly called "Hertzian waves" or "aetheric waves". Hertz’s death in 1894 brought published reviews of his earlier discoveries, and a renewed interest on the part of Marconi. He was permitted to briefly study the subject under Augusto Righi, a University of Bologna physicist and neighbor of Marconi who had done research on Hertz’s work. Righi had a subscription to The Electrician where Oliver Lodge published detailed accounts of the apparatus used in his (Lodge’s) public demonstrations of wireless telegraphy in 1894.
Early Experimental Devices
Marconi began to conduct experiments, building much of his own equipment in the attic of his home at the Villa Griffone in Pontecchio, Italy. His goal was to use radio waves to create a practical system of "wireless telegraphy"—i.e. the transmission of telegraph messages without connecting wires as used by the electric telegraph. This was not a new idea—numerous investigators had been exploring wireless telegraph technologies for over 50 years, but none had proven commercially successful. Marconi did not discover any new and revolutionary principle in his wireless-telegraph system, but rather he assembled and improved a number of components, unified and adapted them to his system.
Marconi’s system had the following components:
- A relatively simple oscillator, or spark producing radio transmitter, which was closely modeled after one designed by Righi, in turn similar to what Hertz had used;
- A wire or capacity area placed at a height above the ground;
- A coherer receiver, which was a modification of Edouard Branly’s original device, with refinements to increase sensitivity and reliability;
- A telegraph key to operate the transmitter to send short and long pulses, corresponding to the dots-and-dashes of Morse code; and
- A telegraph register, activated by the coherer, which recorded the received Morse code dots and dashes onto a roll of paper tape.
Similar configurations using spark-gap transmitters plus coherer-receivers had been tried by others, but many were unable to achieve transmission ranges of more than a few hundred meters.
At first, Marconi could only signal over limited distances. In the summer of 1895 he moved his experimentation outdoors. After increasing the length of the transmitter and receiver antennas, and arranging them vertically, and positioning the antenna so that it touched the ground, the range increased significantly. Soon he was able to transmit signals over a hill, a distance of approximately 1.5 km (0.93 mi). By this point he concluded that with additional funding and research, a device could become capable of spanning greater distances and would prove valuable both commercially and militarily.
Finding little interest in his work in Italy, in early 1896 at the age of 21, Marconi traveled to London, accompanied by his mother, to seek support for his work; Marconi spoke fluent English in addition to Italian. While there, he gained the interest and support of William Preece, the Chief Electrical Engineer of the British Post Office. The apparatus that Marconi possessed at that time was strikingly similar to that of one in 1882 by A. E. Dolbear, of Tufts College, which used a spark coil generator and a carbon granular rectifier for reception. A plaque on the outside of BT Centre commemorates Marconi’s first public transmission of wireless signals from that site. A series of demonstrations for the British government followed—by March 1897, Marconi had transmitted Morse code signals over a distance of about 6 km (3.7 mi) across the Salisbury Plain. On 13 May 1897, Marconi sent the first ever wireless communication over open sea. It transversed the Bristol Channel from Lavernock Point (South Wales) to Flat Holm Island, a distance of 6 km (3.7 mi). The message read "Are you ready". The receiving equipment was almost immediately relocated to Brean Down Fort on the Somerset coast, stretching the range to 16 km (9.9 mi).
Impressed by these and other demonstrations, Preece introduced Marconi’s ongoing work to the general public at two important London lectures: "Telegraphy without Wires", at the Toynbee Hall on 11 December 1896; and "Signaling through Space without Wires", given to the Royal Institution on 4 June 1897.
Numerous additional demonstrations followed, and Marconi began to receive international attention. In July 1897, he carried out a series of tests at La Spezia in his home country, for the Italian government. A test for Lloyds between Ballycastle and Rathlin Island, Ireland, was conducted on 6 July 1898. The English channel was crossed on 27 March 1899, from Wimereux, France to South Foreland Lighthouse, England, and in the autumn of 1899, the first demonstrations in the United States took place, with the reporting of the America’s Cup international yacht races at New York.
Marconi sailed to the United States at the invitation of the New York Herald newspaper to cover the America’s Cup races off Sandy Hook, NJ. The transmission was done aboard the SS Ponce, a passenger ship of the Porto Rico Line. Marconi left for England on 8 November 1899 on the American Line’s SS St. Paul, and he and his assistants installed wireless equipment aboard during the voyage. On 15 November the St. Paul became the first ocean liner to report her imminent arrival by wireless when Marconi’s Needles station contacted her sixty-six nautical miles off the English coast.
According to the Proceedings of the United States Naval Institute, the Marconi instruments were tested around 1899 and the tests concerning his wireless system found that the "[…] coherer, principle of which was discovered some twenty years ago, [was] the only electrical instrument or device contained in the apparatus that is at all new".
“See if you can hear anything, Mr. Kemp!”
Around the turn of the century, Marconi began investigating the means to signal completely across the Atlantic, in order to compete with the transatlantic telegraph cables. Marconi established a wireless transmitting station at Marconi House, Rosslare Strand, Co. Wexford in 1901 to act as a link between Poldhu in Cornwall and Clifden in Co. Galway. He soon made the announcement that on 12 December 1901, using a 152.4-m (500 ft) kite-supported antenna for reception, the message was received at Signal Hill in St John’s, Newfoundland (now part of Canada) signals transmitted by the company’s new high-power station at Poldhu, Cornwall.
The distance between the two points was about 3,500 km (2,200 mi). Heralded as a great scientific advance, there was—and continues to be—some skepticism about this claim, partly because the signals had been heard faintly and sporadically. There was no independent confirmation of the reported reception, and the transmissions, consisting of the Morse code letter S sent repeatedly, were difficult to distinguish from atmospheric noise. (A detailed technical review of Marconi’s early transatlantic work appears in John S. Belrose’s work of 1995.) The Poldhu transmitter was a two-stage circuit. The first stage operated at lower voltage and provided the energy for the second stage to spark at a higher voltage. Nikola Tesla, a rival in transatlantic transmission, stated after being told of Marconi’s reported transmission that "Marconi [… was] using seventeen of my patents."
Feeling challenged by skeptics, Marconi prepared a better organized and documented test. In February 1902, the SS Philadelphia sailed west from Great Britain with Marconi aboard, carefully recording signals sent daily from the Poldhu station. The test results produced coherer-tape reception up to 2,496 km (1,551 mi), and audio reception up to 3,378 km (2,099 mi). The maximum distances were achieved at night, and these tests were the first to show that for medium wave and long wave transmissions, radio signals travel much farther at night than in the day. During the daytime, signals had only been received up to about 1,125 km (699 mi), less than half of the distance claimed earlier at Newfoundland, where the transmissions had also taken place during the day. Because of this, Marconi had not fully confirmed the Newfoundland claims, although he did prove that radio signals could be sent for hundreds of km, despite some scientists’ belief they were essentially limited to line-of-sight distances.
On 17 December 1902, a transmission from the Marconi station in Glace Bay, Nova Scotia, Canada, became the first radio message to cross the Atlantic from North America. On 18 January 1903, a Marconi station built near South Wellfleet, Massachusetts in 1901 sent a message of greetings from Theodore Roosevelt, the President of the United States, to King Edward VII of the United Kingdom, marking the first transatlantic radio transmission originating in the United States. This station also was one of the first to receive the distress signals coming from the RMS Titanic. However, consistent transatlantic signaling was difficult to establish.
Marconi began to build high-powered stations on both sides of the Atlantic to communicate with ships at sea, in competition with other inventors. In 1904 a commercial service was established to transmit nightly news summaries to subscribing ships, which could incorporate them into their on-board newspapers. A regular transatlantic radio-telegraph service was finally begun on 17 October 1907 between Clifden Ireland and Glace Bay, but even after this the company struggled for many years to provide reliable communication.
The two radio operators aboard the Titanic—Jack Phillips and Harold Bride—were not employed by the White Star Line, but by the Marconi International Marine Communication Company. Following the sinking of the ocean liner, survivors were rescued by the RMS Carpathia of the Cunard Line. Also employed by the Marconi Company was David Sarnoff, the only person to receive the names of survivors immediately after the disaster via wireless technology. Wireless communications were reportedly maintained for 72 hours between the Carpathia and Sarnoff, but Sarnoff’s involvement has been questioned by some modern historians. When the Carpathia docked in New York, Marconi went aboard with a reporter from The New York Times to talk with Bride, the surviving operator. On 18 June 1912, Marconi gave evidence to the Court of Inquiry into the loss of the Titanic regarding the marine telegraphy’s functions and the procedures for emergencies at sea. Britain’s postmaster-general summed up, referring to the Titanic disaster, "Those who have been saved, have been saved through one man, Mr. Marconi…and his marvelous invention."
Marconi’s work built upon the discoveries of numerous other scientists and experimenters. His "two-circuit" equipment, consisting of a spark-gap transmitter plus a coherer-receiver, was similar to those used by other experimenters, and in particular to that employed by Oliver Lodge in a series of widely reported demonstrations in 1894. There were claims that Marconi was able to signal for greater distances than anyone else when using the spark-gap and coherer combination, but these have been disputed (notably by Tesla).
In 1900 Alexander Stepanovich Popov stated to the Congress of Russian Electrical Engineers that:
"[…] the emission and reception of signals by Marconi by means of electric oscillations [was] nothing new. In America, the famous engineer Nikola Tesla carried the same experiments in 1893."
The Fascist regime in Italy credited Marconi with the first improvised arrangement in the development of radio. There was controversy whether his contribution was sufficient to deserve patent protection, or if his devices were too close to the original ones developed by Hertz, Popov, Branley, Tesla, and Lodge to be patentable.
While Marconi did pioneering demonstrations for the time, his equipment was limited by being essentially untuned, which greatly restricted the number of spark-gap radio transmitters which could operate simultaneously in a geographical area without causing mutually disruptive interference. (Continuous-wave transmitters were naturally more selective and less prone to this deficiency). Marconi addressed this defect with a patent application for a much more sophisticated "four-circuit" design, which featured two tuned-circuits at both the transmitting and receiving antennas. This was issued as British patent number 7,777 on 26 April 1900. However, this patent came after significant earlier work had been done on electrical tuning by Nikola Tesla and Oliver Lodge. (As a defensive move, in 1911 the Marconi Company purchased the Lodge-Muirhead Syndicate, whose primary asset was Oliver Lodge’s 1897 tuning patent. This followed a 1911 court case in which the Marconi company was ruled to have illegally used the techniques described under Lodge’s tuning patent.) Thus, the "four-sevens" patent and its equivalents in other countries was the subject of numerous legal challenges, with rulings which varied by jurisdiction, from full validation of Marconi’s tuning patent to complete nullification.
In 1943, a lawsuit regarding Marconi’s numerous other radio patents was resolved in the United States. The court decision was based on the prior work conducted by others, including Nikola Tesla, Oliver Lodge, and John Stone Stone, from which some of Marconi patents (such as U.S. Patent 763,772) stemmed. The U. S. Supreme Court stated that,
The Tesla patent No. 645,576, applied for 2 September 1897 and allowed 20 March 1900, disclosed a four-circuit system, having two circuits each at transmitter and receiver, and recommended that all four circuits be tuned to the same frequency. [… He] recognized that his apparatus could, without change, be used for wireless communication, which is dependent upon the transmission of electrical energy.
In making their decision, the court noted,
Marconi’s reputation as the man who first achieved successful radio transmission rests on his original patent, which became reissue No. 11,913, and which is not here [320 U.S. 1, 38] in question. That reputation, however well-deserved, does not entitle him to a patent for every later improvement which he claims in the radio field. Patent cases, like others, must be decided not by weighing the reputations of the litigants, but by careful study of the merits of their respective contentions and proofs."
The court also stated that,
It is well established that as between two inventors priority of invention will be awarded to the one who by satisfying proof can show that he first conceived of the invention."
The Supreme Court of the United States did not dispute Marconi’s original British patent nor his reputation as the inventor of radio. The US Supreme Court stated that his original patent (which became reissue 11,913) was not being disputed.
The case was resolved in the U.S. Supreme Court by overturning most of Marconi’s patents. At the time, the United States Army was involved in a patent infringement lawsuit with Marconi’s company regarding radio, leading observers to posit that the government nullified Marconi’s other patents to render moot claims for compensation (as, it is speculated, the government’s initial reversal to grant Marconi the patent right in order to nullify any claims Tesla had for compensation). In contrast to the United States system, Mr. Justice Parker of the British High Court of Justice upheld Marconi’s "four-sevens" tuning patent. These proceedings made up only a part of a long series of legal struggles, as major corporations jostled for advantage in a new and important industry.
The 1895 public demonstrations by J.C. Bose in Calcutta regarding radio transmission were conducted before Marconi’s wireless signaling experiments on Salisbury Plain in England in May 1897. In 1896, the Daily Chronicle of England reported on his UHF experiments: "The inventor (J.C. Bose) has transmitted signals to a distance of nearly a mile and herein lies the first and obvious and exceedingly valuable application of this new theoretical marvel." Marconi, while being fully aware of Bose’s prior work in this area, nonetheless claimed exclusive patent rights.
Invention of Radio
Within the history of radio, several people were involved in the invention of radio and there were many key inventions in what became the modern systems of wireless. Radio development began as "wireless telegraphy". Closely related, radio was developed along with two other key inventions, the telegraph and the telephone. During the early development of wireless technology and long after its wide use, disputes persisted as to who could claim credit for the invention of radio. The matter was important for economic, political and nationalistic reasons.
Physics of wireless signalling
Several different electrical, magnetic, or electromagnetic physical phenomena can be used to transmit signals over a distance without intervening wires.
The various methods for wireless signal transmissions include:
- Electrical conduction through the ground, or through water.
- Magnetic induction
- Capacitive coupling
- Electromagnetic wave
All these physical phenomena, as well as more speculative concepts such as conduction through air, have been tested for purposes of communication. Early researchers may not have understood or disclosed which physical effects were responsible for transmitting signals. Early experiments used the existing theories of the movement of charged particles through an electrical conductor. There was no theory of electromagnetic wave propagation to guide experiments before Maxwell’s treatise and its verification by Hertz and others.
Capacitive and inductive coupling systems today are used only for short-range special purpose systems. The physical phenomenon used generally today for long-distance wireless communications involves the use of modulation of electromagnetic waves, which is radio.
Radio antennas radiate electromagnetic waves that can reach the receiver either by ground wave propagation, by refraction from the ionosphere, known as sky wave propagation, and occasionally by refraction in lower layers of the atmosphere (tropospheric ducting). The ground wave component is the portion of the radiated electromagnetic wave that propagates close to the Earth’s surface. It has both direct-wave and ground-reflected components. The direct-wave is limited only by the distance from the transmitter to the horizon plus a distance added by diffraction around the curvature of the earth. The ground-reflected portion of the radiated wave reaches the receiving antenna after being reflected from the Earth’s surface. A portion of the ground wave energy radiated by the antenna may also be guided by the Earth’s surface as a ground-hugging surface wave.
Below is a selection of pertinent events and individuals, from 1860 to 1910, related to the development of radio.
Please take time to further explore more about GUGLIELMO MARCONI,
WIRELESS TELEGRAPHY, INVENTION OF RADIO. and the TIMELINE OF
RADIO TECHNOLOGY by accessing the Wikipedia articles
Other Events on this Day:
Pennsylvania becomes the second state to ratify the U.S. Constituton.
The first Bible society in the United States is organized in Philadelphia.
Alexis de Tocqueville crosses the Tennessee River on route from Louisville to Memphis during his journey through America.
Joseph Rainey of South Carolina is sworn in as the first black member of the U.S. House.
Italian inventor Guglielmo Marconi receives the first transatlantic radio transmission, a simple Morse code "S," sent across 2,200 miles from Cornwall, England, to St. John’s in Newfoundland, Canada.
The world’s first motel, the Motel Inn, opens in San Luis Obispo, California.
American oil tycoon Armand Hammer purchases a 1508 notebook containing notes and drawings by Leonardo da Vinci at a Christie’s auction for more than $5 million. Following Hammer’s death, the manuscript will be resold in 1994 to Microsoft founder Bill Gates for a record $30.8 million.
The U.S. Supreme Court reaches a decision in Bush v. Gore, ruling to halt the recount of presidential ballots in Florida and effectively making Republican George W. Bush the winner over Democrat Al Gore.
Dates and events based on:
William J. Bennett and John Cribb, (2008) The American Patriot’s Almanac Daily Readings on America. (Kindle Edition)
Background information is from Wikipedia articles on:
Wikipedia: Guglielmo Marconi…
Wikipedia: Invention of Radio…
Wikipedia: Fugitive Slave…
Brainy Quote: GUGLIELMO MARCONI Quotes…
Brainy Quote: WIRELESS Quotes…
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