Nikola Tesla - The Founder of High-Frequency and Radio Engineering Page 10

Tesla used his high-frequency currents for electromedicine (today’s diathermy and d’Arsonvalization), for the production of ozone, nitrogen compounds from the air, and for the melting of iron and steel, but primarily for the realization of radio technology.

2) Tesla’s Investigations in the Field of Radio Technology (1892–1900)

a) Basic Plan of Radio Technology

In his lecture in London in 1892, Tesla demonstrated that high-frequency currents could travel through a single wire without a return path, and he experimentally succeeded in lighting lamps and powering electric motors with such a system using only one wire. Having established this, he connected the secondary coil of his oscillator on one side to a highly elevated vertical wire and on the other side to the earth, thus creating open circuits that were capable of radiating electrical energy in the form of electromagnetic waves over greater distances. This led him to the idea of using such open circuits initially for wireless telegraphy, and already in the aforementioned lecture he presented his basic plan for radio technology with a receiving and transmitting station and open circuits, which included Tesla coils, an antenna, and an earth connection. At the transmitting station, the electrical energy of the primary closed circuit of Tesla’s oscillator is converted into a high-frequency current, which is then sent via Tesla’s transformer to an open antenna circuit and radiated as high-frequency energy into space, so that at a distance, at the receiving (similarly arranged) station, it can be used for signaling without wires. Tesla explicitly states the following in that lecture: “Experiments, which are of great scientific interest, can probably best be carried out on a ship at sea. In this way we could certainly transmit, if nothing else, at least intelligible signals.”

In his lecture before the Franklin Institute in 1893, Tesla presented this basic plan of radio technology, in connection with his high-frequency apparatus and circuits, even more extensively. He showed a diagram of a transmitting and receiving station with highly elevated antennas and an earth connection, and stated that the distances over which wireless signals could be sent by means of high-frequency currents and such open circuits were simply a function of the high-frequency energy employed. He further stated that between the individual circuits of both stations it is necessary