A RIFLE shot rent the silence of the Italian countryside. That signal gave Guglielmo Marconi confirmation that the rudimentary equipment he was using had worked. Electromagnetic waves generated by a transmitter and radiated into space had been picked up a mile and a half [2.5 km] away by a receiver. It was 1895. Although back then nobody could fully grasp all the implications, that rifle shot opened the way for a technology that has since revolutionized our world—radio communication.
The nature of electromagnetic waves had already been studied by a number of scientists. In 1831, English physicist Michael Faraday demonstrated that an electric current could produce a magnetic field and induce a current in a second circuit isolated from the first but placed in proximity to it.
In 1864, Scottish physicist James Maxwell theorized that the energy generated by such fields could radiate in waves—like ripples on the surface of a pond—but at the speed of light. Later, German physicist Heinrich Hertz confirmed Maxwell’s theory, producing electromagnetic waves and detecting them at close range, as did Ernest Rutherford (later, Lord Rutherford) in New Zealand. But by adapting and improving the available equipment and adding a crude antenna of his own, Marconi managed to transmit a telegraphic signal a considerable distance. Wireless telegraphy was on the way!
In 1896, 21-year-old Marconi moved from Italy to England, where he was presented to William Preece, chief engineer of the General Post Office. Preece was interested in applying Marconi’s system to maritime communications between points that could not be connected by cable. He offered Marconi the help of technicians and the use of laboratories for his experiments. In a few months, Marconi succeeded in increasing the power of signals transmitted to a range of six miles [10 km]. In 1897, Marconi founded the Wireless Telegraph and Signal Company, Ltd., with the aim of transforming wireless telegraphy into a commercially viable system.
In 1900 a 200-mile [300 km] radiotelegraphic link was made between Cornwall and the Isle of Wight in south England, demonstrating what was once considered impossible—the overstriding of the earth’s curvature with radio waves. It had been thought that signals would not be received past the horizon, since electromagnetic waves travel in straight lines. Then the first important orders for radios began to arrive. The British Admiralty commissioned the installation of radio sets on 26 ships, as well as the construction and maintenance of six land stations. The following year Marconi succeeded in bridging the Atlantic with a faint signal of three dots that indicated the letter S in Morse code. The invention’s future was ensured.
At first, wireless telegraphy could transmit neither words nor music, just Morse code. However, in 1904 a great step forward was taken with the advent of the diode, the first valve vacuum tube, which made transmission and reception of the voice possible. This transformed wireless telegraphy into radio as we know it today.
In 1906, in the United States, Reginald Fessenden broadcast music that was picked up by ships 50 miles [80 km] away. In 1910, Lee De Forest staged a live transmission of a concert given by the famous Italian tenor Enrico Caruso for the benefit of radio amateurs in New York. A year before, signals to regulate timepieces were transmitted from the Eiffel Tower in Paris, France, for the first time. That same year, 1909, the first radio-assisted rescue of survivors took place, from the steamers Florida and Republic, which had collided in the Atlantic. Three years later, over 700 survivors of the Titanic disaster were also saved, thanks to an SOS sent by radio.
As early as 1916, the possibility of having a radio in every home was envisioned. The use of valves made production of efficient, low-cost receivers possible, throwing open the door that led to the widespread development of commercial radio. The boom came first in the United States, where there were 8 stations by the end of 1921 and 564 had been licensed by November 1, 1922! In many homes, apart from the lighting system, the radio was the first appliance to be hooked up to the electricity supply.
A Hundred Years of Radio
In 1954 the favorite pastime of people in Italy was listening to the radio. Despite the success of television, radio is still very popular. In most European countries, the radio is listened to for information or entertainment by 50 to 70 percent of the population. It is estimated that in the United States, there is a radio in 95 percent of the vehicles, 80 percent of the bedrooms, and more than 50 percent of the kitchens.
One of the reasons for the radio’s popularity, even in the era of television, is its portability. Moreover, according to a survey, radio possesses a “power of emotional and imaginative involvement far superior to that of television.”
During 1995, celebrations in Italy for the centennial of Marconi’s experiment offered occasion to reflect on the progress made by radio. Numerous scientists have made contributions to the transformation of the first crude devices into the advanced systems of today.
Now, thanks to digital audio broadcasting, which is a system of numeric codification of the signal, excellent sound quality is guaranteed. But above and beyond the countless everyday applications of radio, the invention was the starting point for TV, radar, and various other technologies.
Radio astronomy, for example, is based on the reception and analysis of radio waves emitted by heavenly bodies. Without radio the development of space technology would have been impossible. All satellite applications—television, telephone, data gathering—depend on the use of radio waves. The technological development of transistors into microchips led first to pocket calculators and computers and then to international information networks.
Mobile telephones capable of connecting any two points on the face of the earth, or almost, are already a reality. The prospect now is the arrival of palm-size wireless receivers—a combination of TV, telephone, computer, and fax. These receivers will be capable of tuning in to hundreds of video, audio, and text channels and will allow users to exchange electronic mail with others.
One cannot be certain what the future holds for this field. But radio technology continues to advance, so other remarkable developments are likely to come.
The explanation of the phenomenon came in 1902, when physicists Arthur Kennelly and Oliver Heaviside theorized about the existence of an atmospheric layer that reflected electromagnetic waves—the ionosphere.