Guglielmo Marconi

Radio work

From youth, Marconi was interested in science and electricity. In the early 1890s, he began working on the idea 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 and inventors had been exploring wireless telegraph technologies and even building systems using electric conduction, electromagnetic induction and optical (light) signalling for over 50 years, but none had proven technically and commercially successful. A relatively new development came from Heinrich Hertz, who, in 1888, demonstrated that one could produce and detect electromagnetic radiation, based on the work of James Clerk Maxwell. At the time, this radiation was commonly called "Hertzian waves", and is now generally referred to as radio waves.

There was a great deal of interest in radio waves in the physics community, but this interest was in the scientific phenomenon, not in its potential as a communication method. Physicists generally looked on radio waves as an invisible form of light that could only travel along a line of sight path, limiting its range to the visual horizon like existing forms of visual signalling. Hertz's death in 1894 brought published reviews of his earlier discoveries including a demonstration on the transmission and detection of radio waves by the British physicist Oliver Lodge and an article about Hertz's work by Augusto Righi. Righi's article renewed Marconi's interest in developing a wireless telegraphy system based on radio waves, a line of inquiry that Marconi noted other inventors did not seem to be pursuing.

Developing radio telegraphy

At the age of 20, Marconi began to conduct experiments on radio waves, building much of his own equipment in the attic of Villa Griffone, the Marconi family residence in Pontecchio, now in the municipality of Sasso Marconi, Italy, with the help of his butler, Mignani. The attic laboratory was later remembered as the Stanza dei Bachi ("silkworm room"), because it occupied a former silkworm room in the villa. Marconi built on Hertz's original experiments and, at the suggestion of Righi, began using a coherer, an early detector based on the 1890 findings of French physicist Édouard Branly and used in Lodge's experiments, which changed resistance when exposed to radio waves. In the summer of 1894, he built a storm alarm made up of a battery, a coherer, and an electric bell, which went off when it picked up the radio waves generated by lightning.

Late one night, in December 1894, Marconi demonstrated a radio transmitter and receiver to his mother, a set-up that made a bell ring on the other side of the room by pushing a telegraphic button on a bench. Supported by his father, Marconi continued to read the available literature and developed ideas from physicists who were experimenting with radio waves. He developed devices, such as portable transmitters and receiver systems, that could work over increasing distances, turning what was essentially a laboratory experiment into a useful communication system. Marconi later described his 1895 apparatus in his Nobel lecture. The system included:

• A relatively simple oscillator or spark-producing radio transmitter;
• A wire or metal sheet capacity area suspended at a height above the ground;
• A coherer receiver, which was a modification of Édouard 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.

In the summer of 1895, Marconi moved his experiments outdoors on his father's estate at Villa Griffone, in Pontecchio near Bologna. He tried different arrangements and shapes of antenna, but even with improvements he was able to transmit signals only up to 800 metres (0.5 mile), a distance Oliver Lodge had predicted in 1894 as the maximum transmission distance for radio waves.

Transmission breakthrough

A breakthrough came in the summer of 1895, when Marconi found that a much greater range could be achieved after he raised the height of his antenna and, borrowing from a technique used in wired telegraphy, grounded his transmitter and receiver. With these improvements, the system was able to transmit over hills; in one of the outdoor trials at Villa Griffone, it reached beyond the Celestini hill, at a distance of about 2 km, using a vertical antenna connected to a buried metal plate in an antenna-earth system. The monopole antenna used a lower frequency of the waves compared to those generated by the dipole antennas used by Hertz, radiating vertically polarized radio waves which could travel longer distances. By this point, Marconi concluded that a device could become capable of spanning greater distances, with additional funding and research, and would prove valuable both commercially and militarily. Marconi's experimental apparatus proved to be the first engineering-complete, commercially successful radio transmission system.

Marconi applied to the Italian Ministry of Post and Telegraphs, then under the direction of Maggiorino Ferraris, explaining his wireless telegraph machine and asking for funding, but never received a response. An apocryphal tale claims that the minister, incorrectly named first as Emilio Sineo and later as Pietro Lacava, wrote "to the Longara" on the document, referring to the insane asylum on Via della Lungara in Rome, but the letter was never found.

In 1896, Marconi spoke with his family friend Carlo Gardini, Honorary Consul at the United States Consulate in Bologna, about leaving Italy to go to Great Britain. Gardini wrote a letter of introduction to the Ambassador of Italy in London, Annibale Ferrero, explaining who Marconi was and describing his discoveries. In his response, Ambassador Ferrero advised them not to reveal Marconi's results until after a patent was obtained. He also encouraged Marconi to come to Britain, where he believed it would be easier to find the necessary funds to turn his experiments into practical use. Finding little interest or appreciation for his work in Italy, Marconi travelled to London in early 1896 at the age of 21, accompanied by his mother, to seek support for his work. He spoke fluent English in addition to Italian. Marconi arrived at Dover, where a Customs officer opened his case and found various apparatuses. The officer contacted the Admiralty in London, and, amid concerns in the United Kingdom about Italian anarchists and suspicion that Marconi might be importing a bomb, his equipment was destroyed.

While in the United Kingdom, Marconi gained the interest and support of William Preece, the Chief Electrical Engineer of the General Post Office (GPO). Marconi applied for a patent on 2 June 1896. British Patent number 12039, titled "Improvements in Transmitting Electrical impulses and Signals, and in Apparatus therefor", became the first patent for a communication system based on radio waves.

Demonstrations and achievements

Marconi gave a series of demonstrations in Britain in 1896 and 1897, including in London, on Salisbury Plain, and across the Bristol Channel. By March 1897, he had transmitted Morse code signals over a distance of about 3 miles (5 km) across Salisbury Plain. On 13 May 1897, Marconi sent the first wireless communication over open sea: a message was transmitted over the Bristol Channel from Flat Holm Island to Lavernock Point near Cardiff, a distance of 3 miles (4.8 km). The message read "Are you ready". The transmitting equipment was almost immediately relocated to Brean Down Fort on the Somerset coast, stretching the range to 10 miles (16 km).

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 "Signalling 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 Lloyd's between the Marine Hotel in Ballycastle and Rathlin Island, both in County Antrim in Ulster, Ireland, was conducted on 6 July 1898 by George Kemp and Edward Edwin Glanville. A transmission across the English Channel was accomplished on 27 March 1899, from Wimereux, France to South Foreland Lighthouse, England. Marconi set up an experimental base at the Haven Hotel, Sandbanks, Poole Harbour, Dorset, where he erected a 100-foot high mast. He became friends with the van Raaltes, the owners of Brownsea Island in Poole Harbour, and his steam yacht, the Elettra, was often moored on Brownsea or at the Haven Hotel. Marconi would later purchase the vessel after the Great War and convert it to a seaborne laboratory from which he would conduct many of his experiments. Among the Elettra's crew was Adelmo Landini, his personal radio operator, who was also an inventor.

In July 1898, Marconi's system was also used to report the Kingstown Regatta off the Irish coast, an early use of wireless telegraphy for live reporting of a sporting event.

In December 1898, the British lightship service authorised the establishment of wireless communication between the South Foreland lighthouse at Dover and the East Goodwin lightship, twelve miles distant. On 17 March 1899, the East Goodwin lightship sent the first wireless distress signal, a signal on behalf of the merchant vessel Elbe which had run aground on Goodwin Sands. The message was received by the radio operator of the South Foreland lighthouse, who summoned the aid of the Ramsgate lifeboat.

In 1899, Marconi sailed to the United States at the invitation of The New York Herald newspaper to cover that year's America's Cup international yacht races off Sandy Hook, New Jersey. His first demonstration was a transmission from 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 Saint Paul, and he and his assistants installed wireless equipment aboard during the voyage. Marconi's wireless brought news of the Second Boer War, which had begun a month before their departure, to passengers at the request of "some of the officials of the American line." On 15 November the SS Saint Paul became the first ocean liner to report her imminent return to Great Britain by wireless when Marconi's Royal Needles Hotel radio station contacted her 66 nautical miles off the English coast. The first Transatlantic Times, a newspaper containing wireless transmission news from the Needles Station at the Isle of Wight, was published on board the SS Saint Paul before its arrival.

Transatlantic transmissions

At the beginning of the 20th century, Marconi turned to the problem of transmitting wireless signals across the Atlantic, in competition with the existing transatlantic telegraph cables. He constructed a high-power transmitting station at Poldhu in Cornwall, England. Marconi had initially intended to conduct receiving tests from Cape Cod in the United States, but after storms damaged the equipment there he established a temporary receiving station at Signal Hill in St. John's, Newfoundland (now part of Canada). On 12 December 1901, using an antenna suspended from a kite, he reported hearing the Morse code letter "S" transmitted repeatedly from Poldhu, over a distance of about 2,200 miles (3,500 km).

The receiving detector associated with the Newfoundland experiment later became the subject of an attribution dispute. A device preserved by the Science Museum Group, known as the "Italian Navy" coherer, is catalogued as a modified carbon-mercury-iron semiconductor diode detector of a type invented by Jagadish Chandra Bose in 1899. The museum associates it with Marconi's December 1901 experiment and notes that it may be the detector on which the transmitted "S" signals were heard. Historical studies state that Marconi obtained the detector through Lieutenant Luigi Solari of the Royal Italian Navy, and have examined the relationship between the apparatus supplied to Marconi and Bose's earlier work on self-restoring detectors. The controversy concerns the origin and attribution of the receiving detector used in the 1901 experiment, rather than the overall development of Marconi's long-distance wireless telegraphy system.

Marconi's reported reception in Newfoundland was widely celebrated, but its evidential basis was later questioned by technical historians. No automatic record of the signal was made at Signal Hill: Marconi and his assistant listened through a telephone receiver for the expected repeated letter S. Later analyses have also noted uncertainty about the wavelength used and the difficulty of transatlantic daytime propagation at the likely frequencies. The 1901 experiment therefore remains historically important as Marconi's reported first transatlantic reception, although the reception itself has continued to be the subject of technical debate.

In February 1902, Marconi conducted more systematic tests aboard the SS Philadelphia while it sailed westward from Great Britain, recording signals transmitted daily from Poldhu. According to his Nobel lecture, readable messages were received by a recording instrument at distances of up to 1,551 miles (2,496 km), while test letters were received at distances of up to 2,099 miles (3,378 km). Marconi also observed during these tests that long-distance reception was substantially better at night than during daylight. These results provided recorded evidence of long-distance wireless propagation, although they did not by themselves resolve the question of the reported Newfoundland reception.

During 1902, Marconi also developed a magnetic detector, which subsequently replaced the coherer in much of the equipment used by his company. In December of that year, official transatlantic wireless messages were exchanged between Poldhu and a new Marconi station at Table Head, near Glace Bay, Nova Scotia. Parks Canada recognises the Glace Bay site for the first exchange of radio messages across the Atlantic.

At South Wellfleet, Massachusetts, a Marconi station was used on 18 January 1903 for an exchange of messages between United States President Theodore Roosevelt and King Edward VII of the United Kingdom. The United States National Park Service describes this event as the first public two-way wireless communication between Europe and America.

Marconi continued to construct high-powered stations on both sides of the Atlantic and to develop wireless communication with ships at sea. In 1904, his company established a commercial service transmitting nightly news summaries to subscribing ships for inclusion in their on-board newspapers. A regular commercial transatlantic radiotelegraph service between Glace Bay and Clifden, Ireland, opened on 17 October 1907, although reliable transatlantic communication remained technically difficult for several years.

Titanic

Before the Titanic disaster, the value of maritime wireless had already been demonstrated in the 1909 rescue following the collision between RMS Republic and SS Florida off Nantucket. Republic carried Marconi wireless equipment, and its operator Jack Binns sent repeated CQD distress calls that helped bring rescue ships to the scene and saved more than 1,500 people.

The role played by Marconi Co. wireless in maritime rescues raised public awareness of the value of radio, especially after the sinking of RMS Titanic on 15 April 1912 and RMS Lusitania on 7 May 1915.

RMS Titanic radio operators Jack Phillips and Harold Bride were not employed by the White Star Line but by the Marconi International Marine Communication Company. After the sinking of the ocean liner, survivors were rescued by the RMS Carpathia of the Cunard Line. There was a distance of 93 km (58 miles) between the two ships. When Carpathia docked in New York, Marconi went aboard with a reporter from The New York Times to talk with Bride, the surviving operator. The disaster increased public recognition of Marconi's wireless system and of its importance for maritime safety.

On 18 June 1912, Marconi gave evidence to the British Wreck Commissioner's Inquiry into the loss of Titanic regarding the functions of marine wireless telegraphy and procedures for emergencies at sea. Britain's Postmaster-General, Herbert Samuel, summed up the perceived importance of wireless communication in the disaster: "Those who have been saved, have been saved through one man, Mr Marconi ... and his marvellous invention."

Marconi was offered free passage on Titanic before she sank, but had taken Lusitania three days earlier. As his daughter Degna later explained, he had paperwork to do and preferred the public stenographer aboard that vessel.

Continuing work

Over the years, the Marconi companies gained a reputation for being technically conservative, in particular by continuing to use inefficient spark-transmitter technology, which could be used only for radio-telegraph operations, long after it was apparent that the future of radio communication lay with continuous-wave transmissions, which were more efficient and could be used for audio transmissions. Somewhat belatedly, the company began significant work with continuous-wave equipment in 1915, after the introduction of the oscillating vacuum tube, or valve.

The New Street Works factory in Chelmsford was the location of one of the first public entertainment radio broadcasts in Britain, on 15 June 1920, when Dame Nellie Melba performed in a broadcast organised by the Marconi Company. In 1922, the Marconi Company operated broadcasting stations at 2MT Writtle, near Chelmsford, and at 2LO in Marconi House, London, both of which helped pave the way for the formation of the British Broadcasting Company.

In 1924, the Marconi-linked company Radiofono was one of the companies that contributed to the formation of the Unione Radiofonica Italiana (URI), the first Italian radio broadcasting concessionaire and a predecessor of RAI.

Politics and military service

In 1914, Marconi was appointed to the Senate of the Kingdom of Italy by Victor Emmanuel III for having rendered eminent services to the nation. He was also appointed Honorary Knight Grand Cross of the Royal Victorian Order in the United Kingdom. During World War I, after Italy joined the Allied side, Marconi served in military and naval technical roles connected with wireless communication. According to the historical records of the Italian Senate, he was appointed a lieutenant in the military engineers in 1915, later held naval ranks including captain and commander, and was promoted to rear admiral in the reserve in 1936. In 1929, he was granted the hereditary title of marquess by royal decree.

Fascism

In 1923, Marconi joined the National Fascist Party. Under the Fascist regime he held several prominent public offices: in 1927 he became president of the National Research Council, and on 19 September 1930 he was appointed president of the Royal Academy of Italy, a position he held until his death. His presidency of the Royal Academy of Italy also made him a member of the Fascist Grand Council.

Marconi publicly associated himself with Fascism. In one speech, he stated: "I reclaim the honour of being the first fascist in the field of radiotelegraphy, the first who acknowledged the utility of joining the electric rays in a bundle, as Mussolini was the first in the political field who acknowledged the necessity of merging all the healthy energies of the country into a bundle, for the greater greatness of Italy." During the Second Italo-Ethiopian War, contemporary press reports stated that Marconi was expected to assist Italian forces in communications work.

Research by Annalisa Capristo has argued that Jewish candidates were systematically excluded from the Royal Academy of Italy during Marconi's presidency, before the introduction of Italy's 1938 racial laws. Reporting on Capristo's archival findings, The Guardian stated that Marconi marked Jewish candidates' records with the letter "E" and that no Jewish candidates were admitted to the academy during his tenure.

Death and posthumous

The Marchese di Marconi had suffered from heart disease for years before he died in Rome on 20 July 1937, at the age of 63.

A state funeral was held for him. As a tribute, shops on the street where he lived were "Closed for national mourning". At 6 pm on the following day, the time designated for the funeral, radio transmitters around the world observed two minutes of silence in his honour. The British Post Office also sent a message requesting that all broadcasting ships honour Marconi with two minutes of broadcasting silence.

At his own request, Marconi's funeral was held in his native city of Bologna, in the San Petronio Basilica, and his coffin was initially laid to rest in the Certosa cemetery. In 1941, his body was exhumed and buried in the Mausoleum of Guglielmo Marconi, built by architect Marcello Piacentini at Villa Griffone in Pontecchio, where Marconi had carried out his first experiments. The municipality of Sasso Bolognese and the village of Pontecchio were renamed Sasso Marconi and Pontecchio Marconi in his memory in 1938.

After Marconi's death, the Italian state began the process of acquiring Villa Griffone and its surrounding park. The villa was declared a national monument in 1939 and became the property of the Fondazione Guglielmo Marconi in 1941, the same year in which the mausoleum was completed and inaugurated. The Marconi Museum was opened inside Villa Griffone in 1999.

In 1943, Marconi's steam yacht, Elettra, was commandeered and refitted as a warship by the German Kriegsmarine. The following year, she was sunk by the British Royal Air Force on 22 January. After the war, the Italian government tried to retrieve the wreckage to rebuild the boat; the wreckage was removed to Italy. Eventually, the idea was abandoned, and the wreckage was cut into pieces which were distributed among Italian museums.

1943 United States Supreme Court patent decision

On 21 June 1943, in Marconi Wireless Telegraph Co. of America v. United States, the Supreme Court of the United States reviewed a Court of Claims case brought by the Marconi Wireless Telegraph Company of America against the United States government for the alleged use of wireless patents during World War I. The case involved four patents: two issued to Marconi, including U.S. Patent No. 763,772 and reissue No. 11,913, one issued to Oliver Lodge, and one issued to John Ambrose Fleming.

The Court held that broad claims in Marconi Patent No. 763,772 were invalid because they had been anticipated by John Stone Stone. The ruling concerned the patent claims before the Court and did not invalidate Marconi's earlier patent for radio transmission.

Personal life

Marconi was a friend of Charles and Florence van Raalte, the owners of Brownsea Island, and of their daughter, Margherita. In 1904, he met Margherita's Irish friend, The Hon. Beatrice O'Brien (1882–1976), the daughter of the 14th Baron Inchiquin. On 16 March 1905, Guglielmo and Beatrice were married, and spent their honeymoon on Brownsea Island. They had three daughters: Lucia (born and died 1906), Degna (1908–1998), and Gioia (1916–1996); and a son, Giulio (1910–1971), who eventually became the 2nd Marchese di Marconi. In 1913, the family returned to Italy and became part of Rome society; Beatrice served as a lady-in-waiting to Queen Elena. At Marconi's request, his marriage to Beatrice was annulled on 27 April 1927, so he could remarry.

Marconi wanted to marry Maria Cristina Bezzi-Scali (2 April 1900 – 15 July 1994), the only daughter of Francesco, Count Bezzi-Scali. To do this, he had to be confirmed in the Catholic faith and became a practising member of the Church. He had been baptised Catholic but was brought up as a member of the Anglican Church. On 12 June 1927, he married Maria in a civil ceremony, with a religious ceremony performed on 15 June. He was 53 years old, while Maria was 27. They had one daughter, Maria Elettra Elena Anna (born 1930). For unexplained reasons, Marconi left his entire fortune to his second wife and their only child, and nothing to the children of his first marriage.

In 1931, Pope Pius XI commissioned Marconi to build Vatican Radio's short-wave station, and the first papal radio broadcast took place on 12 February of that year. Marconi personally introduced the broadcast and announced at the microphone: "With the help of God, who places so many mysterious forces of nature at man's disposal, I have been able to prepare this instrument which will give to the faithful of the entire world the joy of listening to the voice of the Holy Father."

Recognition

Memberships

Awards

Honours

Commemoration

• In 1974, Italy marked the centenary of Marconi's birth with a commemorative 100 lire coin.
• In 1975, Marconi was inducted into the National Inventors Hall of Fame.
• In 1978, Marconi was inducted into the NAB Broadcasting Hall of Fame.
• In 1990, the Bank of Italy issued a 2,000 lire banknote featuring Marconi on the front and his yacht Elettra, radio towers, and early radio apparatus on the reverse.
• In 2001, the Royal Mint issued a commemorative £2 coin celebrating the 100th anniversary of Marconi's first wireless transmission across the Atlantic.
• Marconi's early experiments in wireless telegraphy were recognised by two IEEE Milestones: one in Switzerland in 2003 and one in Italy in 2011.
• In 2009, Italy issued a commemorative silver 10 euro coin honouring the centenary of Marconi's Nobel Prize.
• In 2009, he was inducted into the New Jersey Hall of Fame.
• The Dutch radio academy bestows the Marconi Awards annually for outstanding radio programmes, presenters and stations.
• The National Association of Broadcasters in the United States bestows the annual NAB Marconi Radio Awards for outstanding radio programmes and stations.

Tributes and namesakes

• A funerary monument to Marconi can be seen in the Basilica of Santa Croce, Florence, but his remains are in the Mausoleum of Guglielmo Marconi in Sasso Marconi, Italy. His former villa, adjacent to the mausoleum, is the Marconi Museum (Italy), which preserves many of his instruments and documents.
• A Guglielmo Marconi sculpture by Attilio Piccirilli stands in Washington, D.C.
• A granite obelisk stands on the cliff top near the site of Marconi's Poldhu Wireless Station in Cornwall, commemorating the first transatlantic wireless transmission.
• Marconi Plaza, an urban park square named after the inventor in 1937, is located in Philadelphia, Pennsylvania. It includes a later bronze statue of Marconi, erected in 1975.

Places and organisations named after Marconi include:

Outer space

• The asteroid 1332 Marconia is named in his honour.
• The lunar crater Marconi on the far side of the Moon is also named after him.

Italy

• Bologna Guglielmo Marconi Airport, the airport of Bologna.
• Guglielmo Marconi University, a private university in Rome.
• Ponte Guglielmo Marconi, a bridge in Rome.

Australia

• Australian football club Marconi Stallions.

Canada

• The Marconi's Wireless Telegraph Company of Canada, later CMC Electronics, was created in 1903 by Guglielmo Marconi. In 1925 the company was renamed the Canadian Marconi Company, which was acquired by English Electric in 1953. The company later became CMC Electronics Inc.; its historical radio business was sold in 2002 to Ultra Electronics and became Ultra Electronics TCS Inc., now Ultra Communications.
• The Marconi National Historic Sites of Canada was created by Parks Canada as a tribute to Marconi's role in the development of radio telecommunications. The site is located in Glace Bay, Nova Scotia.

United States

• Marconi Conference Center State Historic Park, site of the former transoceanic Marshall Receiving Station in Marshall, California.
• Marconi-RCA Bolinas Transmitting Station in Bolinas, California.
• Station KPH, Marconi Wireless Telegraph Company of America in Inverness, California.
• Marconi Wireless Telegraphy Station on Oahu's North Shore, Hawaii.
• Marconi Beach in Wellfleet, Massachusetts, part of the Cape Cod National Seashore, located near the site of his first transatlantic wireless signal from the United States to Britain.
• New Brunswick Marconi Station, now the Guglielmo Marconi Memorial Plaza in Somerset, New Jersey.
• Marconi Bust presented by RFMD Co-founder Jerry D. Neal at Qorvo Headquarters (Greensboro, North Carolina)
• Belmar Marconi Station, now the InfoAge Science History Center in Wall Township, New Jersey.
• La Scuola d'Italia Guglielmo Marconi in New York City.
• Marconi Plaza, Philadelphia, Pennsylvania.

Collections

The main Marconi Collection is held by the University of Oxford, to which it was presented by the Marconi Corporation in 2004. Its objects are kept by the History of Science Museum, Oxford, while the documentary archives, including papers relating to Marconi and the development of wireless telegraphy and records of Marconi companies, are held by the Bodleian Library.

Patents

United Kingdom

• British patent No. 12,039 (1897) "Improvements in Transmitting Electrical impulses and Signals, and in Apparatus therefor". Date of Application 2 June 1896; Complete Specification Left, 2 March 1897; Accepted, 2 July 1897. This was later claimed by Oliver Lodge to contain ideas of his own which he had not patented.
• British patent No. 7,777 (1900) "Improvements in Apparatus for Wireless Telegraphy". Date of Application 26 April 1900; Complete Specification Left, 25 February 1901; Accepted, 13 April 1901.
• British patent No. 10,245 (1902) "Improvements in Receivers suitable for Wireless Telegraphy", relating to Marconi's magnetic detector.
• British patent No. 5,113 (1904) "Improvements in Transmitters suitable for Wireless Telegraphy". Date of Application 1 March 1904; Complete Specification Left, 30 November 1904; Accepted, 19 January 1905.
• British patent No. 21,640 (1904) "Improvements in Apparatus for Wireless Telegraphy". Date of Application 8 October 1904; Complete Specification Left, 6 July 1905; Accepted, 10 August 1905.
• British patent No. 14,788 (1905) "Improvements in or relating to Wireless Telegraphy". Date of Application 18 July 1905; Complete Specification Left, 23 January 1906; Accepted, 10 May 1906.

United States

• U.S. patent 586,193 "Transmitting electrical signals", using a Ruhmkorff coil and Morse code key. Filed December 1896; patented July 1897.
• U.S. patent 624,516 "Apparatus employed in wireless telegraphy".
• U.S. patent 627,650 "Apparatus employed in wireless telegraphy".
• U.S. patent 647,007 "Apparatus employed in wireless telegraphy".
• U.S. patent 647,008 "Apparatus employed in wireless telegraphy".
• U.S. patent 647,009 "Apparatus employed in wireless telegraphy".
• U.S. patent 650,109 "Apparatus employed in wireless telegraphy".
• U.S. patent 650,110 "Apparatus employed in wireless telegraphy".
• U.S. patent 668,315 "Receiver for electrical oscillations".
• U.S. patent 676,332 "Apparatus for wireless telegraphy", a later practical version of the system.
• U.S. patent 757,559 "Wireless telegraphy system". Filed 19 November 1901; issued 19 April 1904.
• U.S. patent 760,463 "Wireless signalling system". Filed 10 September 1903; issued 24 May 1904.
• U.S. patent 763,772 "Apparatus for wireless telegraphy", relating to the four-tuned-circuit system later considered in Marconi Wireless Telegraph Co. of America v. United States.
• U.S. patent 786,132 "Wireless telegraphy". Filed 13 October 1903.
• U.S. patent 792,528 "Wireless telegraphy". Filed 13 October 1903; issued 13 June 1905.
• U.S. patent 884,986 "Wireless telegraphy". Filed 28 November 1902; issued 14 April 1908.
• U.S. patent 884,987 "Wireless telegraphy".
• U.S. patent 884,988 "Detecting electrical oscillations". Filed 2 February 1903; issued 14 April 1908.
• U.S. patent 884,989 "Wireless telegraphy". Filed 2 February 1903; issued 14 April 1908.
• U.S. patent 924,560 "Wireless signalling system". Filed 9 August 1906; issued 8 June 1909.
• U.S. patent 935,381 "Transmitting apparatus for wireless telegraphy". Filed 10 April 1908; issued 28 September 1909.
• U.S. patent 935,382 "Apparatus for wireless telegraphy".
• U.S. patent 935,383 "Apparatus for wireless telegraphy". Filed 10 April 1908; issued 28 September 1909.
• U.S. patent 954,640 "Apparatus for wireless telegraphy". Filed 31 March 1909; issued 12 April 1910.
• U.S. patent 997,308 "Transmitting apparatus for wireless telegraphy". Filed 15 July 1910; issued 11 July 1911.
• U.S. patent 1,102,990 "Means for generating alternating electric currents". Filed 27 January 1914; issued 7 July 1914.
• U.S. patent 1,148,521 "Transmitter for wireless telegraphy". Filed 20 July 1908; issued 3 August 1915.
• U.S. patent 1,226,099 "Transmitting apparatus for use in wireless telegraphy and telephony". Filed 31 December 1913; issued 15 May 1917.
• U.S. patent 1,271,190 "Wireless telegraph transmitter".
• U.S. patent 1,377,722 "Electric accumulator". Filed 9 March 1918.
• U.S. patent 1,981,058 "Thermionic valve". Filed 14 October 1926; issued 20 November 1934.
• U.S. patent RE11913 "Transmitting electrical impulses and signals and in apparatus therefor". Filed 1 April 1901; issued 4 June 1901.