Regular

Nikola Tesla explaining his “World Wireless System“ and how it differs from today’s radio and wireless technology.

(Pre-hearing interview with Nikola Tesla’s legal counsel in 1916 to protect his radio patents from the Guglielmo Marconi and the Marconi Company.)

Tesla:

“The idea was to put the coil, with reference to the primary, in an inductive connection which was not close—we call it now a loose coupling—but free to permit a great resonant rise. That was the first single step, as I say, toward the evolution of an invention which I have called my “Magnifying Transmitter.” That means, a circuit connected to ground and to the antenna, of a tremendous electromagnetic momentum and small damping factor, with all the conditions so determined that an immense accumulation of electrical energy can take place…

“I mean that you have to have in the circuit, inertia. You have to have a large self-inductance in order that you may accomplish two things: First, a comparatively low frequency, which will reduce the radiation of the electromagnetic waves to a comparatively small value, and second, a great resonant effect. That is not possible in an antenna, for instance, of large capacity and small self-inductance. A large capacity and small self-inductance is the poorest kind of circuit which can be constructed; it gives a very small resonant effect. That was the reason why in my experiments in Colorado the energies were 1,000 times greater than in the present antennae.

Legal Counsel:

"You say the energy was 1,000 times greater. Do you mean that the voltage was increased, or the current, or both?”

Tesla:

“Yes, both. To be more explicit, I take a very large self-inductance and a comparatively small capacity, which I have constructed in a certain way so that the electricity cannot leak out. I thus obtain a low frequency; but, as you know, the electromagnetic radiation is proportionate to the square root of the capacity divided by the self-induction. I do not permit the energy to go out; I accumulate in that circuit a tremendous energy. When the high potential is attained, if I want to give off electromagnetic waves, I do so, but I prefer to reduce those waves in quantity and pass a current into the earth, because electromagnetic wave energy is not recoverable while the earth current is entirely recoverable, being the energy stored in an elastic system.“

Legal Counsel:

"What elastic system do you refer to?”

Tesla:

“I mean this: If you pass a current into a circuit with large self-induction, and no radiation takes place, and you have a low resistance, there is no possibility of this energy getting out into space; therefore, the impressed impulses accumulate.”

Legal Counsel:

“Let’s see if I understand this correctly. If you have radiation or electromagnetic waves going from your system, the energy is wasted?”

Tesla:

“Absolutely wasted. From my circuit you can get either electromagnetic waves, 90 percent of electromagnetic waves if you like, and 10 percent in the current energy that passes through the earth. Or, you can reverse the process and get 10 percent of the energy in electromagnetic waves and 90 percent in energy of the current that passes through the earth.

“It is just like this: I have invented a knife. The knife can cut with the sharp edge. I tell the man who applies my invention, you must cut with the sharp edge. I know perfectly well you can cut butter with the blunt edge, but my knife is not intended for this. You must not make the antenna give off 90 percent in electromagnetic and 10 percent in current waves, because the electromagnetic waves are lost by the time you are a few arcs around the planet, while the current travels to the uttermost distance of the globe and can be recovered.

“This view, by the way, is now confirmed.  Note, for instance, the mathematical treatise of Sommerfeld, [*] who shows that my theory is correct, that I was right in my explanations of the phenomena, and that the profession was completely misled. This is the reason why these followers of mine in high frequency currents have made a mistake. They wanted to make high frequency alternators of 200,000 cycles with the idea that they would produce electromagnetic waves, 90 percent in electromagnetic waves and the rest in current energy. I only used low alternations, and I produced 90 percent in current energy and only 10 percent in electromagnetic waves, which are wasted, and that is why I got my results.“

[*] Editorial note: In 1909, Sommerfeld performed a theoretical analysis of the propagation of radio waves around the earth, solving for the problem of a vertical dipole over a finitely conducting homogeneous ground. He divided the expression for the resulting field into "space wave” and “surface wave” components. The surface wave part had nearly identical properties to a unique plane surface wave solution to James Clark Maxwell’s equations that had been identified by Jonathon Zenneck two years previously. The field amplitudes varied inversely as the square root of the horizontal distance from the source and decayed exponentially with height above the interface. [Sommerfeld, Arnold N., “Uber die Ausbreitung der Wellen in der drahtlosen Telegraphie,” Annalen der Physik, March 16, 1909 (vol. 28, no. 4), OP. 665-736.]

Legal Counsel:

“You spoke… about getting all of the energy from your transmitting into your recieving station by this method of yours. I do not understand how you can get all of it.”

Tesla:

“Oh, that is hardly true; I am speaking as a matter of principle. You never can get all the energy, because there is no such thing as a perfect apparatus.”

Legal Counsel:

“I did not mean it in that sense. I understand that there is, of course, always some loss, but my conception was that when you created a disturbance in the commercial condition of the earth at your transmitting station, that that extended out in all radial directions.”

Tesla:

“Yes, it did.”

Legal Counsel:

“And therefore how, at any given station, can you get more than a small fraction of that energy?”

Tesla:

“Pardon me you are mistaken… In my first efforts, of course I simply contemplated to disturb effectively the earth, sufficiently to operate instruments. Well, you know you must first learn how to walk before you can fly. As I perfected my apparatus, I saw clearly that I can recover, of that energy which goes in all directions, a large amount, for the simple reason that in the system i have devised, one that current got into the earth it had no chance of escaping, because my frequency was low; hence, the electromagnetic radiation was low. The potential, the electric potential, is like temperature. We might as well call potential electric potential. The earth is a vast body. The potential differences in the earth are small, radiation is very small. Therefore, I’d I pass my current into the earth, the energy of the current is stored there as electromagnetic momentum of the vibrations and is not consumed until I put a reciever at a distance, when it will begin to draw the energy and it will go to that point and nowhere else.”

Legal Counsel:

“Why is that, on your theory?”

Tesla:

“I will explain it by an analogue.

"Suppose that the earth were an elastic bag filled with water. My transmitter is equivalent to a pump. I put it on a point of the globe, and work my little piston so as to create a disturbance of that water. If the piston moves slowly, so that the time is long enough for the disturbance to spread over the globe, then what will be the result of my working this pump? The result will be that the bag will expand and contract rhythmically with the motions of the piston, you see. So that, at any point of that bag, there will be a rhythmical movement due to the pulsations of the pump.

"That is only, however, when the period is long. If I were to work this pump very rapidly, then I would create impulses, and the ripples would spread in circles over the surface of the globe. The globe will no longer expand and contract in its entirety, but it will be subject to these outgoing, rippling waves.

"Remember, now, that the water is incompressible, that the bag is perfectly elastic, that there are no hysteretic losses in the bag due to these expansions and contractions; and remember also, that there is a vacuum, in infinite space, so that the energy cannot be lost in waves of sound. Then, if I put at a distant point another little pump, and tune it to the rhythmical pulses of the pump at the central plant, I will excite strong vibrations and will recover power from them, sufficient to operate a receiver. But, if I have no pump there to receive these oscillations, if there is nowhere a place where this elastic energy is transferred into frictional energy (we always use in our devices frictional energy – everything is lost through friction), then there is no loss, and if I have a plant of 1,000 horsepower and I operate it to full capacity, that plant does not take power, it runs idle, exactly as the plant at Niagara. If I do not put any motors or any lamps on the circuit, the plant runs idle. There is a 5,000 horsepower turbine going, but no power is supplied to the turbine except such power as is necessary to overcome the frictional losses.

"Now the vast difference between the scheme of radio engineers and my scheme is this. If you generate electromagnetic waves with a plant of 1,000 horsepower, you are using 1,000 horsepower right along – whether there is any receiving being done or not. You have to supply this 1,000 horsepower, exactly as you have to supply coal to keep your stove going, or else no heat goes out. That is the vast difference. In my case, I conserve the energy; in the other case, the energy is all lost.”

Legal Counsel:

“Mr. Tesla, does that not presuppose that the fluid must be incompressible?”

Tesla:

“I should say so, and electricity, whatever it is, certainly it is incompressible because all our experiments show that.”

Legal Counsel:

“Now, if you were giving that a name, what principle would you say was involved by which the radiation loss, where there is no receiver, becomes a gain or a conservation where there is a receiver?”

Tesla:

“There is no radiation in this case. You see, the apparatus which I have devised was an apparatus enabling one to produce tremendous differences of potential and currents in an antenna circuit. These requirements must be fulfilled, whether you transmit by currents of conduction, or whether you transmit by electromagnetic waves. You want high potential currents, you want a great amount of vibratory energy; but you can graduate this vibratory energy. By proper design and choice of wave lengths, you can arrange it so that you get, for instance, 5 percent in these electromagnetic waves and 95 percent in the current that goes through the earth. That is what I am doing. Or you can get, as these radio men, 95 percent in the energy of electromagnetic waves and only 5 percent in the energy of the current. The apparatus is suitable for one or the other method. I am not producing radiation with my system; I am suppressing electromagnetic waves. In my system, you should free yourself of the idea that there is radiation, that the energy is radiated. It is not radiated; it is conserved.”

“Nikola Tesla On His Works With Alternating Currents and Their Application to Wireless Telegraphy, and Transmission of Power.”Twenty First Century Books, Breckenridge, Colorado, 2002.