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Jurassic Telecommunications, Part II

The Global Influences Leading Up To Marconi's "Lucky 7's" Patent

By Don Kimberlin

This is the second of an ongoing series under the generic title of "Jurassic Telecommunications." In its various articles, one can see that the modes of electronic communications so taken for granted today are really largely late Victorian technologies first realized in an era before electronics; one in which there was no amplification, no frequency conversion and only battery power. Considering that, it's really amazing that the pioneers accomplished what they did.


(As published in NARTE News, Volume 17 Number 3, October, 1999)


Guglielmo Marconi and his Patent with the Sevens 

Most technologies begin as a method in search of a problem, and communication by radio is no exception. For most of the half-century following successful use and expansion of the electric telegraph, a number of experimenters added contributions to radio. Some even seem to have had useful radio in their grasp, only to let it lie fallow. It finally all came together in April 1900 with 26-year-old Guglielmo Marconi's British patent 7777.


Up to that time, American dentist Mahlon Loomis had demonstrated in 1865 that an electrical disturbance could be caused in a kite-flown "aerial wire" by opening and closing the circuit of another kite-flown "aerial wire" at a distance of 18 miles between mountain tops in Virginia. He even obtained a U.S. patent (issued in 1872) indicating it might be used for "telegraphy," but never obtained funding to back further development, in all likelihood because the then-powerful Western Union Telegraph Company had a number of other, nearer-term technological fish to fry, not the least of were both transcontinental and transatlantic telegraph businesses in addition to a burgeoning domestic telegraph network. Loomis died a broken and bitter man.

Karl Braun in Germany discovered "one-way conduction" in metal sulfide crystals in 1874, but the applicability of this phenomenon to detecting radio signals was not to be thought of for several decades in the future.

Based on taking up a prize challenge in 1879, German physicist Heinrich Hertz demonstrated in 1887 and 1888 transmission of electromagnetic waves indoors across university lecture halls, showing students that invisible waves that propagated much like light did indeed exist. Since Hertz' laboratory demonstration devices consisted simply of spark gaps in metallic rings resonant at around 150 MHz, with no amplification, he could show and announced the contention that whatever was being transmitted, it had no commercial potential. Although a young man, Hertz unfortunately died at age 36, just before he might have seen others adding to his work and leading toward everyday uses.

Edouard Branly in France started work to study nerve conduction in 1885. His need for a sensitive electrical detector resulted in the Branly Coherer, a tube of loosely packed metal filings that would clump together when a weak current flowed through it. The coherer, adopted and modified by others became radio's first practical signal detector.

William Crookes suggested in 1892 that electromagnetic waves might be used for wireless telegraphy, even though this was five years before J.J. Thompson would announce the existence of electrons. At the time, no one was interested.

Oliver Lodge, an English professor at University College, Liverpool, independently achieved results similar to Hertz, publishing just a month after Hertz (which means we might have called radio waves "Lodgian waves") By 1894, Lodge was demonstrating transmission of electromagnetic waves through walls in London and later at Oxford University. Lodge added an important function to the Branly coherer: A mechanical "tikker" that randomized the filings in the coherer after each detection event.

Ambrose Fleming, later to become a close associate of Marconi, was in the audience and later wrote he had seen Lodge transmit alphabetic characters using the Morse telegraphic code; letters that formed intelligible messages. (The actual message content, regrettably, seems to have been lost.) Also, Lodge, in connection with related interests he had concerning the nature of lightning, had already defined basic properties of electromagnetic waves, showing that the period of a wave in a resonant circuit was equal to 2 pi LC. Lodge at the time stayed close to his profession of Professor of Experimental Physics, and thus had no interest in further developing his nascent "wireless telegraph." Although he has developed the concept of tuning a circuit, using the musical term "syntony," Lodge does not begin to exploit his discoveries until 1901, after Marconi has begun to use the concepts in practical wireless telegraphy.

In the face of all this, Marconi's first knowledge of electromagnetic waves did not occur until 1894, when, as an unmatriculated protégé of Professor Righi at Bologna, he reads about Hertz' demonstrations. Professor Righi was himself replicating and expanding on Hertz' work, but with even smaller loops than Hertz; loops that suggest Righi's waves had a frequency in the region of 3 gigaHertz, which would, of course, result in an even shorter transmission range than Hertz had
shown.

Marconi, well-to-do son of a Bologna merchant family, built his own experiments on the family estate and by 1895, succeeded in signaling over a distance of about 2 kilometers. Most exciting to him was that the signals traveled over a hilltop, between a transmitter and receiver that were out of sight of each other. At the time, and for some years later, many still contended that electromagnetic waves behaved exactly like light, implying a range no farther than line of sight. Marconi had to repeatedly demonstrate transmission beyond the optical horizon to a skeptical world. 

In Russia, Alexander Popov worked at improving the Branly coherer by selecting the material and size of filings, adding his own "tikker." Popov demonstrated detection of electromagnetic waves generated by lightning as much as 30 kilometers distant when connected to a lightning rod that was, of course, an antenna for the coherer. An academic like Lodge, even though he wrote that his apparatus might be used for signaling, Popov never developed the notion of sending messages to a complete fruition.

By 1896, receiving no interest from the Italian government in his work, Marconi took his apparatus to England, where he could count on influence and land owned by relatives based on his family's connection to the Irish Jameson Whisky family. On his arrival in England, frightened customs inspectors smashed his machinery, fearing it to be part of an Italian anarchist plot. Fortunately, it is simple enough that it can be rebuilt without difficulty.

Also in 1896, Nikola Tesla of Serbia, whose primary interest was electrical power transmission rather than communications, had developed a rotary arc transmitter and the notion of a vertical "aerial wire" as parts of a proposition to transmit electric power without wires. Although incomplete of Tesla's contribution at the moment, Marconi applied for British patents covering "wireless telegraphy," showing a clear purpose to transmit information by electromagnetic waves as the end purpose of his invention.

By 1897, starting a barrage of experimentation and development that was to characterize the personality of both Marconi and his companies, Marconi demonstrated a range of first 7-1/2, then 14 kilometers. Based on that success, he founded his first English company, The Marconi Wireless Telegraph Company, Limited. Returning to Italy in the latter half of 1897, he demonstrated wireless telegraphy with ships 18 kilometers offshore and over the horizon. At the end of 1897, he was back in England showing that a station on the Isle of Wight could communicate with ships as much as 30 kilometers distant, By 1898, he opened a commercial wireless telegraph service to Rathlin O'Birne Lighthouse Island near the entrance to Donegal Bay in
northwestern Ireland.

On March 27, 1899, Marconi joined England to Europe with wireless telegraphy between his shore station at South Foreland Light and a station he built at Wimereux, 50 kilometers across the Channel. He was nearly in a position to compete with submarine telegraph cables across the Dover Strait that had been operating since 1851. The notion of competing with telegraph companies was obvious.

By the summer of 1899, Marconi had finally waited out and overridden political obstacles in the Royal Navy and was invited to place his wireless on three naval ships during maneuvers. The range to his shore station ran as far as 160 kilometers, while ships could signal each other as far as 110 kilometers and occasionally as far as 136 kilometers. By this point, interference was becoming intolerable with no real tuning or band-limiting of emissions. Marconi had to get to work on employing some "syntony," which Lodge had patented in 1897. Marconi took "syntony" a step farther than Lodge, providing tuning at both the spark transmitter and the coherer receiver as part of his famous Patent 7777. This did not keep Lodge from later suing Marconi in 1910 and settling for cash in 1911 over patent infringements.

However, in 1900, encouraged by his recent successes, Marconi told the board of his newly formed Marconi International Marine Communication Company" that he wanted to construct high-powered wireless transmitters to span the Atlantic Ocean. The result, as we all know, was the epochal transmission of the Morse letter "S" between Poldhu Point near Mullion on England's Lizard Peninsula and Heart's Content in Newfoundland on December 12, 1901. The details of that accomplishment, and those of several later starting parallel developers to Marconi, are stories for another time.

What did happen by April 1900 was that Marconi uniquely had combined Professor Righi's transmitter, Branly's coherer, Tesla's elevated antenna and Lodge's tuned circuits to realize what ultimately became first wireless telegraphy, then speech, music, control tones and data transmission by radio. And, it's doubtful anyone with less financial resource, political influence and staying power than Marconi could have accomplished the progress he had made by the turn of the century. It's an appropriate time now to consider how far we have progressed in the 100 years since Marconi got it all together in 1900.

Want to know more? Here are some websites with more detail on radio's earliest years:
http://www.webcom.com/radioweb/educate/timeline.html
http://wwwkoi.ptti.ru/eng/forum/article1.html
http://home.luna.nl/~arjan-muil/radio/intune.html
http://www.hal-pc.org/~bvarc/jan1996.htm
http://www.engr.mun.ca/~gpeters/greats.html

Don Kimberlin has written many articles about his experiences over the years, as well as those who were the pioneers in the telecommunications and broadcast industries.