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Re: Tesla Coil RF Transmitter



Original poster: "Gary Peterson" <gary@xxxxxxxxxxxx>


Original poster: "Antonio Carlos M. de Queiroz" <acmdq@xxxxxxxxxx>

Tesla list wrote:

Original poster: "Gary Peterson" <gary@xxxxxxxxxxxx>

Original poster: stork <stork@xxxxxxxxxxxxxxxxxxx>

Does the current in the earth from the ground connection move as a conduction current . . . ?

Yes, true conduction current flows outward through the earth from a Tesla coil transmitter's ground terminal. Assuming a uniform texture and composition of the surrounding terrain, this current diminishes in strength equally in all horizontal directions as the distance from the terminal increases. This situation changes if an identically tuned Tesla receiving transformer is brought into operation at another location. In this case there is an increase in the current that flows from the transmitter's ground terminal and a conduction current passes through Earth in direction of the receiver's ground terminal.

This looks quite excessive. There is no way where the transmitter can be aware of the existence of the receiver, if it is out of its local field. The receiver receives signal significant time after it was transmitted, and can't inform the transmitter to redirect its ground current on its direction. The power transmitted by radio stations does not depend on the number of receivers receiving the station... The energy that is not recovered by the receivers, taken only from the electromagnetic waves at their immediate vicinity (their local field area), is lost.

Antonio Carlos M. de Queiroz

The earth is 4,000 miles radius. Around this conducting earth is an atmosphere. The earth is a conductor; the atmosphere above is a conductor, only there is a little stratum between the conducting atmosphere and the conducting earth which is insulating. Now, on the basis of my experiments in my laboratory on Houston Street, the insulating layer of air, which separates the conducting layer of air from the conducting surface of the earth, is shown to scale as you see it here [see http://www.teslaradio.com/images/079.gif]. Those [radii lines] are 60deg of the circumference of the earth, and you may notice that faint white line, a little bit of a crack, that extends between those two conductors. Now, you realize right away that if you set up differences of potential at one point, say, you will create in the media corresponding fluctuations of potential. But, since the distance from the earth's surface to the conducting atmosphere is minute, as compared with the distance of the receiver at 4,000 miles, say, you can readily see that the energy . . . will be immediately transformed into conduction currents, and these currents will travel like currents over a wire with a return. The energy will be recovered in the circuit, not by a beam that passes along this curve and is reflected and absorbed . . . but it will travel by conduction and will be recovered in this way. Had I drawn this white line to scale on the basis of my Colorado experiments, it would be so thin that you would have to use a magnifying glass to see it.


Counsel

Will you pardon me for interrupting again. You spoke some time ago about getting all of the energy from your transmitting into your receiving 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 perfect apparatus.

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 the disturbance in the electrical condition of the earth at your transmitting station, that that extended out in all radial directions.

Tesla

    Yes, it did.

Counsel

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

Tesla

    Pardon me, you are mistaken.

Counsel

That is what I want you to explain. I must be mistaken, because my conception does not fit in with your statements.

Tesla

    All right, I will explain that.

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, once that current got into the earth it had no chance of escaping, because my frequency was low; hence, the electro-magnetic radiation was low. The potential, the electric potential, is like temperature. We might as well call potential electric temperature. The earth is a vast body. The potential differences [created] in the earth are small, radiation is very small. Therefore, if 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 receiver at a distance, when it will begin to draw the energy and it will go to that point and nowhere else.

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.

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.

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 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. Then you are wondering why you do not get good results. I know why I do not get good results in that way. The apparatus is suitable for one or the other method. I am not producing radiation in my system; I am suppressing electromagnetic waves. But, on the other hand, my apparatus can be used effectively with electromagnetic waves. The apparatus has nothing to do with this new method except that it is the only means to practice it. So that in my system, you should free yourself of the idea that there is radiation, that energy is radiated. It is not radiated; it is conserved. . . .

Nikola Tesla, 1916