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NEWSLETTER
Comparing the Hertz-Wave and Tesla Wireless Systems


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Feed Line No. 9 Article

COMPARING THE HERTZ-WAVE  AND TESLA WIRELESS SYSTEMS
by Gary Peterson

While speaking about his pioneering turn-of-the-century work in the development of the first practical system for wireless telecommunications Tesla said:

". . . 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.  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." [1]

While they are in many respects similar, there are also some significant differences between what might be called the "Tesla wireless system" and the Marconi or Hertz-wave wireless system in common use today.  Both incorporate what is commonly called the "four-tuned circuit" configuration consisting of inductively-coupled radio-frequency circuits, two at the transmitter and two at receiver.  As Tesla made clear, the basic mechanism for producing the radio frequency power is essentially identical. The principle difference is in the antenna or launching structure.


An illustration of Marconi's system showing its 1/4-wave monopole transmitting antenna. [3]  Both the transmitter, on the left, and the receiver are of the original single tuned circuit design.  Early on Marconi redesigned his transmitter using Tesla's coupled tuned circuit invention, while retaining the monopole launching structure.  


The Tesla system with coupled tuned circuits at the transmitting and receiving ends.  The unit on the right is acting as the transmitter. [3]

For our purposes, we will use a power source with a frequency of approximately 136 kHz.  This frequency falls within the 135.7 - 137.8 kHz low-frequency amateur radio band which presently exists in Europe and the U.K.., and has been proposed in the United States [4].  The relationship between wavelength and frequency is given by the equation,

lambda (in feet) = 984 / frequency (in mHz).

Doing the math, the electrical wavelength at 136 kHz is about 7,235 feet.  A vertical quarter-wave Marconi-type antenna might consist of a metal radio tower reaching about 1,800 feet above the earth's surface.

A Tesla-type transmitting tower for this frequency will be much shorter than the monopole.  The bottom third or so consists of a helical resonator followed by a relatively large conducting cylinder connected to a spherical or donut-shaped terminal of large surface area.  At 136 kHz a realistic height for such a structure is on the order of 90 feet.

Tesla revealed this configuration in U.S. Patent No. 1,119,732, "Apparatus for Transmitting Electrical Energy." [5]  The 187-foot Wardenclyffe tower on Long Island embodied the same design.

The problem is to characterize the performance of these two different launching structures in response to the application of radio-frequency alternating current.  In the first case antenna theory tells us, with proper coupling of the transmission line to the structure will be an efficient radiator of electromagnetic energy.

Because of the finite velocity of the electric current flowing through a conductor, it takes a finite amount of time for the applied charge to build up on the antenna.  The electric field follows the charge carriers moving along the vertical monopole antenna and the lines tend to spread out through space toward the position they would occupy under static charge conditions. [*] During the next quarter cycle, the monopole is discharged and some of the lines break away to form closed loops.  The field lines propagate out into space in somewhat the same manner as waves are formed on a pond when a pebble is thrown in.  This action is repeated with each successive RF cycle.  The implication here is that energy is irretrievably lost from the monopole.  This lost energy represents electromagnetic radiation, that is to say, radio waves.  Along with the field energy lost or radiated from the monopole, a certain fraction returns back to the source during each RF cycle.  Consequently, the fields near the antenna represent both energy storage and radiation components.  These are described as the reactive fields and the radiated fields of a radio antenna.

In the case of the Tesla-type launching structure the time delay effect that is responsible for the production of electromagnetic radiation or "radio waves," such as occurs with a quarter-wave monopole radio antenna, is minimized and the stored-energy or reactive component of the field is greatly increased.  While the amount of time expended to charge the structure remains the same, the overall distance between the bottom feed-point and the structure's upper extremity is much smaller.  For example, if the structure is 90 feet in height, when compared with the 1,800-foot tall monopole the greatest overall distance the wave disturbance moves axially along the resonator is about 5 percent of the 136 kHz electrical quarter-wavelength.  The field lines distributed throughout space follow the charge variations much more efficiently.  This means that once the polarity of the RF source is reversed a greater amount of the energy field is recovered or reflected back from free space to the transmitting element and electromagnetic radiation is suppressed.  The base impedance of the helical resonator of a properly configured Tesla magnifying transmitter is very low and this allows the recovered or reflected power to be efficiently applied directly to the earth via what must be a very robust ground connection for optimum efficiency.

A considerable expenditure might be expected for the above-ground antenna structure of a Marconi-type long wave wireless facility, if it is to perform efficiently; installing the buried counterpoise is not as expensive a proposition.  The opposite is the case if the construction of a proper Tesla World Wireless system magnifying transmitter is undertaken.

Again quoting Tesla:

"You see the underground work is one of the most expensive parts of the tower. In this system that I have invented it is necessary for the machine to get a grip of the earth, otherwise it cannot shake the earth.  It has to have a grip on the earth so that the whole of this globe can quiver, and to do that it is necessary to carry out a very expensive construction.  I had in fact invented special machines. . . ."

In conclusion, fundamentally identical electrical oscillators consisting of an RF power source, an elevated conductor and a robust ground connection can be configured in ways which are conducive two different forms of wireless propagation.  Low frequency wireless communications can be accomplished by the production of either electromagnetic radiation in the form of space waves, or the production of ground currents and accompanying trapped surface-waves possibly similar to the Zenneck surface wave.

Once again quoting Tesla, 

"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. . . . This view, by the way, is now confirmed. Note, for instance, the mathematical treatise of Sommerfeld, [6] who shows that my theory is correct, that I was right in my explanations of the phenomena. . . ." [1]

Figure 1. Geometry for Zenneck wave propagation. [7]

 

Figure 8. Zenneck wave field strength decrease for round the world propagation as a function of frequency in kHz. [7]

 

[*] Antenna Theory and Impedance Matching
A radiating dipole field is due to a collection of charged particles oscillating in a conductor comprising a launching structure.  The charge is forced into oscillation by the injection of electromagnetic energy.  This process involves impedance matching of the energy source and the launching structure, as well as the transmission line connecting the two.  The oscillator trades this energy back and forth between its inductive [magnetic] and its capacitive [electrostatic] energy storage components.  Periodic movement of the charge sets up a sinusoidal E-field and cosinusoidal H-field.  The H component carries the magnetic energy and the E component carries the electrostatic energy.  During the oscillation of the charge/field, it's stored energy alternates between a magnetic peak and an electrostatic peak. The oscillation occurs at a fixed frequency primarily dependent upon the geometry of the launching structure and to a lesser extent the proximity of any surrounding objects.  The process of dipole radiation also involves impedance matching, in this case that of the dipole oscillator to the impedance of free space, which is E/H = 377 ohms.  The E/H impedance ratio of the dipole field is determined by the magnitude of source charge and distance through which it oscillates.  The EM wave travels outwards and, encountering the free-space impedance, some portion of the radiated power is reflected back to the launching structure due to more or less of an impedance mismatch.  The remainder continues to radiate away from the antenna, escaping in the form of electromagnetic Hertz waves (see Teaching Electromagnetism Using Advanced Technologies).

The Hertz-wave transmitter launching structure provides a good initial match with free space resulting in the efficient production of electromagnetic waves.  The Tesla-type launching structure is specifically designed to have a poor impedance match with free space.  Its configuration inhibits the launching of electromagnetic space waves.  Provided with sufficient input power, a large magnifying transmitter is capable of breaking down the insulating medium constituted by the denser portions of the earth's atmosphere around and above it.

References

1Nikola Tesla On His Work With Alternating Currents and Their Application to Wireless Telegraphy, Telephony and Transmission of Power

2"The True Wireless"

3)  "The Disturbing Influence of Solar Radiation On the Wireless Transmission of Energy" 

4Notice of Proposed Rule Making, FCC 02-136, 05/15/2002

5Dr. Nikola Tesla � Complete Patents

6)  Uber die Ausbreitlung der Wellen in der drahtlosen Telegraphie," [Annalen der Physik, Vol. 28, March, 1909, pp. 665-736.  ["Propagation of Waves in Wireless Telegraphy," Arnold N. Sommerfeld, Ann. Phys. (Leipzig), 28, 1909, pp. 665-737.]

7)  Corum, K. L. and J. F. Corum, "The Zenneck Surface Wave," Appendix II of "Nikola Tesla, Lightning Observations, and Stationary Waves," 1994.  (See Q&A No. 39 "Can you explain, within accepted laws of physics, what was Tesla doing in Colorado Springs and on Long Island?" for excerpts.)

"Electromagnetic Surface Waves," in Advances in Radio Research. J.A Saxton, editor, Academic Press, Vol. 1, 1964, pp. 157-217.

Burrows, C.R, "The Surface Waves in Radio Propagation Over Plane Earth," Proceedings of the IRE, Vol. 25, No.2, February, 1937, pp. 219-229

Yu. V. Kistovich, "Possibility of Observing Zenneck Surface Waves in Radiation from a Source with a Small Vertical Aperture" [Soviet Physics Technical Physics, Vol. 34, No.4, April, 1989, pp. 391-394.

Schelkunoff, S., and H.T. Friis, Antennas: Theory and Practice, Wiley, 1952, pp. 352-353; 252.

Hill, D. and J.R Wait, "Excitation of the Zenneck Surface Wave by a Vertical Aperture," Radio Science, Vol. 13, No. 6, November-December, 1978, pp. 969-977.

World System
characteristics, regulation, ethical considerations; requirement for eternal vigilance

Regeneration Revisited: ". . . Rudenberg teaches that the antenna interacts with the incoming field, which may be approximately a plane wave, causing a current to flow in the antenna by induction. The [antenna] current, in turn, produces a field in the vicinity of the antenna, which field, in turn, interacts with the incoming field in such a way that the incoming field lines are bent.  The field lines are bent in such a way that the energy is caused to flow from a relatively large portion of the incoming wave front, having the effect of absorbing energy from the wave front into the antenna from a wave front which is much larger than the geometrical area of the antenna."

'Energy Sucking' Radio Antennas: ". . . light waves are about 5000 Angstroms in wavelength, while atoms are more like 1 Angstrom across. How can such tiny "antennas" absorb and emit such long waves?  Usually it takes a half-wave antenna to do this. I never encountered a good explanation for this during my physics education.  It turns out that the explanation is both little-known and fascinating. . . ."

Global resonance may be achieved with an expenditure of at least 37 kW of peak envelope power to the launching structure.
(746 watts = 1 horsepower)

Interplanetary communications
". . . with the novel means, proposed by myself, I can readily demonstrate that, with an expenditure not exceeding two thousand horse-power [1.492 MW], signals can be transmitted to a planet such as Mars with as much exactness and certitude as we now send messages by wire from New York to Philadelphia. These means are the result of long-continued experiment and gradual improvement." -- Collier's Weekly, February 19, 1901 

InterPlaNetary Internet Project defining the architecture and protocols necessary to permit interoperation of the Internet resident on Earth with other remotely located internets resident on other planets or spacecraft in transit.  (See Interplanetary Network Connects Rovers, Orbiters, Agencies and Earth.) 

Establish a world system on Earth.  System transmitters would serve as Ground Station One (GS1), with a similar world system on Mars, bypass orbiting repeaters, facilitate continuous connectivity on and between both planets.  Communications with spacecraft to be investigated.

band-width problem: wave complex, frequency division multiplexing

propagation delay problem: (?)

Revised: 04/15/17 

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