Newspaper and magazine articles related to Nikola Tesla

Nikola Tesla Articles

Newspaper and magazine articles related to Nikola Tesla

A Logical Discussion on the Transmission of Power by Radio

September 6th, 1925
Page number(s):

Experimenters Have Been Devoting a Great Deal of Their Time Trying to Solve This Problem

Radio has sprung unusually fast from technical obscurity to a popular utility, through broadcasting, and to many it seems to have reached its limit of perfection and usefulness. Transmitting stations have arisen in numbers sufficient to intermesh their waves in a blanket which covers every acre of the country. Receiving sets are so Chick that their antennae spider-web the horizon line. The broadcast programs are in portions of the cycle above the reproach of the most fastidious. What more could one want? What more is possible?

In answer to those questions the echoes of a dozen unsolved problems assert themselves. How can static be eliminated? Who will pay for future broadcasting? When can the owner of a set be freed from technical worry? How can receiving set upkeep be minimized? How can distortion be done away with? What are the limiting factors of super-power?

Important Question

The question of who will pay for broadcasting is an old one, and misleading. The people who use the sets, of course, always pay; no matter what distribution or collection system is used. It resolves itself to a queston, rather, of how, by what specific means, will the expenses of broadcasting be paid. At present the sale of sets and parts, and of general merchandise through ethereal advertising, pays, but whether this is an ultimate solution is dubious.

As long as the number of broadcasting stations reads in three figures, and the number of radio manufacturers reads in four, there can hardly be a totally satisfactory distribution of toll. Taxing tubes or batteries would not be fair, for who can say that the owner of a single tube set does not have all the services and advantages in his way that a broadcasting station could give to the owner of an 8-tube set? Government licensing would be no better, for there would be no way of honestly apportioning the collected money.

If there were but two or three manufacturers and that is perfectly feasible if apparatus could be sufficiently developed so that it could be standardized-and four or five broadcasting stations for the entire country, the question of payment for broadcasting could be more satisfactorily met. Apparatus could be rented, like Bell telephones, or sold outright, like standard typewriters, and the user could at all times be sure of reliable maintenance service. The several broadcasters could afford to furnish the best of programs, for they would have a definite and continuous source of revenue.

Distance Wave May Travel

Undoubtedly, with transmitting and receiving apparatus which we have immediately at hand, this could be accomplished with passable success. But the equipment would be expensive and tremendously limited. Super-power would have to be used at the transmitter, and the sensitivity of the receiving sets increased with the increase in distance. As the distance which a Hertz wave transmitter may cover varies approximately with the square of the power used, it is obvious that the wattage would have to exceed that now in use manyfold. Unless the Iwave lengths that were used were widely separated, receiving sets within the vicinity of these powerful transmitters would be interfered with beyond remedy.

In true radio transmission it would writer that a goodly portion seem of the transmitted energy should be recoverable. In our present system it is almost a total loss. One could realize this more fully if all receiving sets had only crystals. From the most powerful of modern transmitters scarcely ever can a crystal set receive satisfactorily over more than a hundred miles. If it had not been for the invention of the vacuum tube detector, oscillator and amplifier the entire system would have been long ago pronounced a failure, or at least relegated to a limited commercial and ship-to-ship code service.

As it stands, the system is backwards. For all the power that is used in the six hundred or so transmitting stations of the country, at least twenty times as much is used in the aggregate of receiving sets. Perhaps this before has been overlooked but it stands out defiantly. Assuming that the six hundred stations broadcast with an average of 1,000 watts, and that two million tube receiving sets consume an average of 6 watts each - which is low, by the way then a total of 600,000 watts would be propagated and a total of 12,000,000 watts be used to make it audible at the receivers.

A Possible Solution

That fundamental weakness is responsible for the necessity of five and eight tube sets those expensive white ele phants which advanced fans must now have in order to meet certain particular requirements. If appreciable power could be conveyed to the receiving set a single tube, or even a crystal, could do the work of an eight-tube super-heterodyne; at the same time securing greater ease of control and less distortion. The works of a set then would need not cost more than $10 or $15, and what upkeep expense there was would be chiefly for the actual broadcasting service.

The cost of bare maintenance of a three-tube set-tubes and battery cost may amount to about $30 a year. Multiply this by two million and we have the figure of $60,000,000 - just for keeping the tubes of the receiving sets lit. It has been said that a broadcasting station cannot keep going on less than $10,000 a year. Some run as high as $200,000. For the entire country the broadcasting upkeep costs must run above $10,000,000 a year.

If but less than a single watt were available at the receiver no tubes would be needed, even for operating a loudspeaker. If energy could be transmitted efficiently total of 2,000 kilowatts would suffice for all our present needs and could be sent from four super stations of 500 kilowatts each.

Then with the best of paid talent the annual cost of both the transmitting and receiving set upkeep could well stay below $15,000,000.

But with our present system this is obviously impossible. The waves sent out are chiefly radiations, and because they are such the greatest part of their energy is irrecoverably lost.

Beam Transmitter

By concentrating the waves into a beam the recoverable energy is increased, but in the same degree the usefulness as a broadcast transmitter is decreased, for the area over which the waves may be intercepted is restricted.

It is this lack of power weakness that is also the main cause of static trouble. Atmospheric electricity will always be with us, and its nature is so closely allied to that of radio waves that it cannot be eliminated in any practical way so long as its intensity approaches and exceeds that of the impulses that are wanted. The only satisfactory solution to the problem seems to be in increasing the available power at the receiver.

The transmitter may be likened to a train announcer, who must send his voice across a noisy railroad terminal. The distinctness with which he can be heard in any part of the building depends solely upon the relative intensity of the voice waves and the noise waves at that particular point. The ones that are greatest, always win.

Distortion, too, is due chiefly to a lack of antenna energy in the receiving set, for it comes through the inaccurate repeating of regeneration, through small differences" in tube characteristics and through interstage transformers. If there was the energy available at the antenna that is now available at the output of the last tube the amplifier could be eliminated, and with it the distortion that it produces.

One often reads in the press the announcement that some one at last has found means to send power by radio. If it were true the industry of the world would be revolutionized. As facts stand, this has not as yet been practically accomplished. Lamps can be lit by the radiations of the ordinary transmitter over very short distances, but the efficiency. is so extremely small that commercial promotion of the phenomenon would be ridiculous.

Nikola Tesla was the first to try to solve the problem, and if success is ever achieved it will doubtless be by his system, into which he has put so much tireless labor. Professor Helmholtz, Lord Kelvin and a number of able contemporaries believe the plan entirely feasible if apparatus could be developed to generate and control the proper kind and intensity of electricity. Tesla has long since done this, and the system seems only to await its application.

The system makes use not of radiation but of true conduction, substituting the earth itself for the wire. That the earth is a conductor is demonstrated by the fact of its extensive use as a telegraph return wire and as the ordinary radio ground connection. Tesla claims it to be a perfect conductor.

The average layman, and electrician as well, is so accustomed to using two wires to connect oll his apparatus that he is likely to ask where the return wire is in Tesla's system. There is none, and for the reason that there need be none. By using alternating currents of proper frequency and correctly proportioning the circuits lamps may be lit and motors run by means of a single wire with no return.

This is easily demonstrable with the common Tesla resonant transformer or Tesla coil. A bank of lamps may be lit or wires melted by attaching one terminal to the coil and the other to an insulated capacity, such as a metal plate or sphere. The capacity serves as a sort of reservoir, which is filled and drained with the alternations of current.

A Pumping System

In his radio transmitter Tesla mounts. a huge capacity, having ideal enveloping surfaces that prevent radiation, on top of a tower and starts up an electrical pumping system, pumping electricity into and out of the earth. The pressure distributes itself over the entire globe as though it were a sphere of but moderate dimensions, and by using receiving apparatus at different parts of the world, connected at one end to the earth and at the other to a similar but smaller capacity, the energy can be recovered with small loss. Distance need not be reckoned with any more than it need be reckoned in a wire circuit with negligible resistance.

If Tesla's system works as well practically as it does theoretically its adaption to broadcasting will go far toward relieving all those problems which were first suggested. It would permit of superpower transmission, with all of the good qualities and none of those that now put a limit to its effectiveness.

Notwithstanding the development of hundreds of new circuits, there has not been a single basic and radical improvement on our present radio system since De Forest invented the three-element vacuum tube. Props have been designed and both transmitting and receiving sets have been pushed to the limits of their capacity, but as for something really new it has yet to appear. The condition is a definite indication that the point of the flattening of the curve has been reached.


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