The origins of wireless communications may be traced back to the German scientist Heinrich Rudolf Hertz, who demonstrated in 1888 that an electric spark of sufficient intensity at the emitting end could be captured by an appropriately designed receiver and induce ‘action at a distance’.

This transmission via the ‘ether’ challenged the classical notions of physics. Whereas Hertz’s experiments spanned just a

few metres, it was the Italian scientist Guglielmo Marconi who constructed a ‘radio’ that transmitted waves over increasing distance: In 1895, he transmitted signals over a distance of 2.5 km, in 1899 over the English Channel and in 1900 over more than 300 km. Marconi’s greatest challenge was to confute the conventional belief that radio waves propagated only linearly and therefore would be unable to follow the curved surface of the earth. In 1901, Marconi established the first wireless transmission over the Atlantic, spanning
over 3500 km from Cornwall to Newfoundland. Maritime applications become the dominant market for wireless, even though only large and expensive ships could carry the wireless equipment and justify the cost.

At the beginning, only gross pulses of energy could be transmitted, and communications was limited to Morse code. Technological improvements, in particular the refinements in radio communication technology such as amplitude modulation (AM)4 and the invention of the thermo-ionic valve, led to the possibility of transmission of speech and music.

However, wireless equipment was a low-volume and high-cost market. Before the start of the First World War there were some 2000–3000 wireless in use in the entire world, most of them in Britain. At the outbreak of the war in Europe the development of wireless was intensified, again mostly for maritime applications. The applications of wireless for ground-troop applications were still met by scepticism from the military planners, and also because of the bulkiness and weight of the equipment.