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Nikola Tesla
(1856 - 1943)

A Profile
By Prof. Anthony C Davies
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Nikola Tesla (1856 – 1943)
was one of a number of scientists (including Maxwell, Hertz, Lodge, Popov) who laid the foundations of radio communications.

Nikola Tesla (1853-1943) was an outstanding and prolific inventor, who not only made fundamental and long-lasting contributions to electrical power generation and transmission, for which he is best known, but also made significant contributions to the early development of radio communications. He is one of several people who have been called the ‘inventor of radio’.

Nikola Tesla
Fig A:  Tesla as a young man (Photo in Tesla Museum, Beograd)

He was born in Smiljan, which is now in Croatia, but Serbs claim him as one of their heroes.  His initial education was in Austria (then part of the Austro-Hungarian Empire).  After leaving his local high school, he attended a polytechnic in Graz, Austria, followed by study at the Charles University in Prague.

After employment with a telephone company in Budapest, he moved to Paris to work for the Continental Company of Edison.  Then, in 1884, he moved to the United States, initially to work with the Edison company, but in 1885 left Edison and founded the ‘Tesla Arc & Light Company’.   It was in USA that he put many of his novel ideas into practice, and where most of his numerous inventions were patented, and so he is often referred to as an ‘American Inventor’.

The 100 Dinar banknote of Serbia shows Nicola Tesla, alongside the definition of the SI unit of magnetic flux (Tesla  Webers per square metre), named after him.

Nikola Tesla
Fig. B    Tesla on Banknote

Notable of his inventions were the rotating magnetic field, the induction motor, a.c. polyphase power transmission (he used two-phase, rather than the three-phase transmission usual today), and the use of power transformers to increase the transmission voltage and hence reduce energy losses.

The scale of his inventions is indicated by his involvement with the Westinghouse Company, to whom he is said to have sold 40 patents in 1888!  These were ones concerned only with polyphase power generation and distribution.  Altogether he is credited with well over 100 US patents – but that 40 of them concerned topics of interest to Westinghouse and were really available by 1888, when he had been in USA for only four years, seems astonishing.

Working with the Westinghouse engineers, his inventions led to the very successful hydro-electric power generation plant at Niagara Falls, in operation by 1895.  It was the first to use polyphase a.c. transmission, which subsequently replaced d.c. power transmission in most power systems worldwide.
Tesla’s contributions to radio were associated with the idea of generating high-frequency continuous oscillations (in contrast to the transient spark-based methods of his contemporary innovators), and he succeeded in direct generation of 15kHz by a rotating electrical alternator – far higher than anything possible before that from a rotating machine.

He developed the concept of two coupled resonant circuits driven by a spark generator (basically, the Tesla Coil – the first air-cored transformer), so producing an output which was a lightly-damped oscillation, approaching his objective of continuous high-frequency oscillations.

By 1893, based on this system of coupled resonant circuits, he showed the need for an aerial and earth connection for radio telegraphy communications.   In a public lecture in Philadelphia in February 1893, he is reported as having discussed the wireless transmission of both energy and signals carrying intelligence.  His ambition was to achieve wireless methods of lighting and operating electrical motors over substantial distances.  He hoped for high-power transmission by radio, which attracted him because, if feasible, this would have eliminated the need for cables to transmit electrical power.   Although he suggested some techniques for this, and apparently believed that some kind of resonance could make this possible, his ideas were associated with doubts and controversy, and it seems likely that there was no realistic method for their success.   He had no technique for generation of high power microwaves, which could have been transmitted in a focussed beam, and there does not seem to be any basis for supposing that the frequencies which he was able to generate could ever have been used in any point-to-point wireless power distribution system.

However, there is some recent speculative work on very low frequency oscillations which does hint at possibilities of remarkable phenomena involving resonance of the Earth’s structure.   Tesla predicted 6Hz as an oscillation frequency of the Earth, and recent measurements have reported 8Hz, remarkably close considering the limited knowledge available to Tesla.

Tesla’s 1893 achievements were followed in 1894 with wireless transmission by Professor Oliver Lodge (12th June 1851 - 22nd August 1940) to a receiver with a dipole antenna and coherer that were carried out at Liverpool University in England.  Popov’s demonstrations were in 1895, and Marconi’s arrival in England was 1896.  There is thus a strong basis for claiming Tesla as a significant “inventor of radio”, and perhaps even the first.

Marconi’s US patent 763772, granted in June 1904, was considered as the fundamental American  radio patent, but in 1943, the US Supreme Court cancelled it, on the grounds that it contained nothing not already in patents granted to Tesla (and Lodge and Stone).

Tesla’s laboratory was destroyed in a fire in 1895, which surely set back his work substantially, yet by 1898, he was demonstrating the remote control of model ships by radio, an invention for which he was awarded a US Patent (No. 613,809) in the same year.

It is said that he conceived his inventions entirely in his mind, and only then transferred the completed ideas to paper.

Marinčić suggests that Tesla’s idea (1903 patent) for a multi-carrier transmission system was a kind of spread-spectrum concept, and that at about the same time, he invented something similar to what is now universally called an ‘integrate and dump’ receiver

Tesla predicted that in the future, humans would communicate wirelessly with small transceivers, and for this was ridiculed by the journalists of the time.  This could be regarded as a visionary prophesy of the mobile phone!

In 2006, the Beograd international airport was renamed the ‘Nikola Tesla’ airport (Fig. G).

A substantial collection of historical material is maintained in the Tesla Museum (Figs C, D) in Beograd, which also has many excellent working models and demonstrations.

Nikola Tesla

Nikola Tesla
Fig C.  Tesla Museum at Krunska 51, Beograd, Serbia

Nikola Tesla
Fig D.  Tesla Museum Admission Ticket

Nikola Tesla
Fig. E    Tribute to Tesla by Major Edwin Armstrong
(the American inventor of the Superheterodyne Receiver and developer of wideband FM Broadcasting)

Nikola Tesla
Fig. F    IEEE Commemorative Plaque at Tesla Museum

Nikola Tesla
Fig. G    Antenna at Wardenclyffe, Long Island, USA  (Picture in Tesla Museum, Beograd)

Nikola Tesla
Fig. H    Nikola Tesla Airport

Anthony C Davies,
Visiting Professor, Kingston University,
Kingston upon Thames, Surrey

Acknowledgements:   Some material is based on a lecture by Prof Aleksandar Marinčić, arranged in Beograd, 13th October 2006 for the IEEE Region 8 Committee.   More information about Tesla is in papers of a Symposium held in Beograd, 18-20 October 2006 to celebrate the 150th anniversary of Telsa’s birth. and in a chapter by Prof  Marinčić in ‘History of Wireless’ (Wiley, 2006) edited by T.K. Sarkar et al.

Further information:

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