Guglielmo Marconi
(trom Wikipedia)

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 metres.

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 kilometres (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.

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.

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. With regard to the Titanic, Britain;'s postmaster general said, "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 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.