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Comparative Study of the Hertz, Marconi and Tesla Low-Frequency Wireless Systems

Four Launching Structures Considered

Comparing the Four Launching Structures

Comparison of Marconi- and Tesla-type Launching Structures

Ground Current Comparison

Electromagnetic Radiation vs. Electrical Conduction

The Norton and Zenneck Surface Waves

Appendix

Antenna Theory and Impedance Matching

Capacity of an Elevated Sphere

Ground Current Behavior

Tesla’s Priority in the Invention of Radio

Tesla’s Early Wireless Work

Investigation of Tesla-Type Wireless Propagation [mathematical modeling and physical validation]

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Four Launching Structures Considered

Consider four basic forms of wireless telecommunications antenna or launching structure, each excited by a radio-frequency power supply.

The first is the Hertz antenna, a vertical 1/2-wave dipole antenna, center fed, positioned 1/2 wavelength above the ground. Clearly this is not a very practical configuration at low frequencies. Nevertheless, it would be possible to improvise a temporary low frequency vertical dipole by suspending a ¼-wavelength section of wire beneath a large helium balloon. The transmitter and battery, mounted in a lightweight box, is attached at the lower end of this wire. A second ¼-wavelength section of wire is connected to the transmitter. Finally the entire assembly is allowed to rise into the air, tethered by a long nylon line. Insulators are inserted at the antenna ends for good measure. The transmitter itself would be wirelessly remote controlled, and could be configured as a cross-band repeater.

Next is the Marconi antenna, a vertical 1/4-wave ground-plane monopole antenna element above a conducting surface, at or slightly above ground level. A vertical conductor with no loading coil and no capacitive top loading is assumed. It is fed at its base by an RF power supply plus an appropriate matching section, with the opposing terminal connected to an elevated ‘counterpoise’ constructed on insulating supports. As an alternative to the counterpoise, a connection is made directly to the earth’s surface. This shallow ground connection is constructed so as to introduce the least possible resistance. Restrictions are imposed by the depth and surface area of the buried conductors, and the local ground conductivity.

The third and forth are the type-one and type-two Tesla launching structures.

The type-one structure is a single a vertical high aspect-ratio 1/4-wave helical resonator with large capacitive top loading and small overall height compared to the electrical 1/4 wavelength. The 1/4-wave resonator is base fed by a low impedance RF power supply, with the opposing terminal grounded. The ground connection is constructed in such a way as to introduce the least possible resistance to ground. In modeling this structure, it is necessary that a complementary receiving structure of identical physical dimensions to that of the transmitting element be included in the circuit. The latter may be either an active or passive receiving element. This system is used when employing the atmospheric conduction method.

The type-two structure consists of two type-one structures, identified as element A and element B, of identical physical dimensions, in close proximity to each other. Element B may be either an active or a passive transmitting element. This system is used when employing the earth resonance method. Note that a distant receiving element is not necessary when modeling the type-two transmitting circuit.

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Comparing the Four Launching Structures

The Hertz antenna, also known as the 1/2-wave dipole antenna, is considered to be a physical embodiment of an electric dipole in free space. In terms of efficiency as a radiator, it approaches an ideal source of electromagnetic radiation emitted in the form of space waves. These space waves can reach the receiver either by ground-wave propagation or by reflection from the ionosphere, known as sky-wave propagation. [Sky waves are not broadly addressed in this paper.]

The electric field that develops when an AC voltage is applied to the terminals of a dipole antenna.

The ground-wave component is the portion of the radiated space wave that propagates close to the earth's surface. It has both direct-wave and ground-reflected components, and under certain conditions a tropospheric ducting component. The direct-wave is limited only by the distance to the horizon from the transmitter plus a small distance added by atmospheric diffraction around the curvature of the earth. The ground-reflected portion of the radiated wave reaches the receiving antenna after being reflected from the earth's surface. A portion of the ground-wave energy radiated by the antenna may also be guided by the earth's surface as a ground-hugging surface wave.

The induced ground-hugging surface-wave component of the ground wave is known as the Norton surface wave. It is the result of electrical currents induced in the ground by refraction of a portion of the reflected-wave component at the earth-atmosphere interface. Upon reflection from the Earth's surface the ground-reflected wave undergoes a 180deg phase reversal. When both transmitting and receiving antennas are on, or close to, the ground and the distance between them approaches the above-described limit, the direct and reflected components tend to cancel each other out, and the resulting field intensity is principally that of the surface wave. Because the ground absorbs part of its energy, the electrical intensity of the surface wave is attenuated at a much greater rate than inversely as the distance. It is the conductivity of the underlying terrain that determines the attenuation of the surface-wave field intensity as a function of distance. The ground currents of a vertically polarized surface wave do not short-circuit a given electric field but rather serve to restore part of the used energy to the following field. The better the conducting surface layer, the more energy returned and the less energy absorbed. [Antennas and Radio Propagation, TM 11-666, Dept. of the Army, Feb. 1953, pp. 17-23.] Prevailing radio wave propagation theory teaches that the surface-wave component is wholly the result of electrical currents induced in the ground by refraction of a portion of the reflected-wave component.

The Marconi antenna is a modified 1/2-wave dipole Hertz antenna, adapted to the real-world conditions encountered in the construction of low frequency transmitters. These adaptations are imposed by the wavelength involved and the resulting physical dimensions required of the antenna. The dipole antenna is modified in that its lower half, 1/4 wavelength long, exists only as an electromagnetic mirror image of its upper counterpart. The resulting 1/4-wave vertical ‘monopole’ antenna takes advantage of the fact that the lower half of the antenna, i.e., the ‘counterpoise,’ acts as a mirror for the radiated energy. This type of structure is known as a ground plane antenna.

The so-called ‘counterpoise’ is a radially symmetrical wire structure erected on insulating supports a short distance above the earth’s surface. One school of thought asserts that the counterpoise operates solely by virtue of its capacitance to the ground. The counterpoise has been defined as “a conductor or system of conductors used as a substitute for earth or ground in an antenna system” [Weik '89].

The counterpoise, in fact, simply forms part of the radiating antenna. It exhibits a current distribution comparable to the current distribution on the vertical monopole section. Radiation from the ‘counterpoise’ is horizontally polarized and, for the most part, self-canceling in the far-field region. (See “Counterpoises, Capacity Hats, and A Standard for Comparing Antennas Suspected of Radiation from the Feedline,” L. B. Cebik, W4RNL, http://www.cebik.com/gp/cp-th.html )

For low frequency antennas it is common practice to bury the counterpoise a few inches in the ground, taking advantage of the earth’s conductivity to increase the physical size of the ground plane. The ground reflects a large amount of the energy that is radiated downward from the antenna mounted over it. In the physical construction of the ground plane it is important to have as high a ground conductivity as possible. The objective is to provide the best possible reflecting surface for the downward radiated energy from the antenna. Typically, the ground plane consists of a number of 1/2 wavelength long bare conductors arranged radially and connected together, buried a short distance [6-8 inches] beneath the earth's surface. These conductors act as part of the reflecting surface as well as making the connection to ground itself.

Not unlike the Hertz antenna, the Marconi antenna is intended as a source electromagnetic radiation in the form of space waves. As with the Hertz antenna, the ground wave component takes both a direct and reflected path from the transmitter to the receiver, and it may also be guided along the earth's surface as a ground-hugging Norton surface wave.

A rough approximation of the e-field lines associated with and near to a grounded ¼-wave monopole antenna located on the earth’s surface. In reality, as the distance from the radiator increase, the e-field lines close back upon themselves to form electromagnetic waves in free space.

The above rendering is a very rough approximation of the e-field lines associated with a ¼-wave ground-plane monopole antenna located on the earth’s surface. The inaccuracy increases rapidly as the distance from the radiator increases. The actual radiation pattern is described in terms of antenna radiation fields. There are three traditional radiation fields in free space as a result of an antenna radiating power. The near-field region is that is closest to the transmitting antenna in which the reactive field dominates over the radiative fields. This region is shown fairly accurately.

Just beyond this is the Fresnel zone in which the radiation fields begin to dominate. An accurate representation will show the e-field lines starting to close back upon themselves to form electromagnetic waves in free space. [Because the earth is neither a perfect insulator nor a perfect conductor,] some of the closed loops will continue on for a time extended downward into the earth or lower half space. In the case of an ideal ¼-wave ground-plane antenna, all of the loops would be in the process of breaking free from the ground to propagate outward in the form of space waves, both sky waves and ground waves.

Eventually a distance will be reached at which all of the loops will have closed back upon themselves. This is the far-field region. Any interaction between the radiated energy and the earth’s surface in this region is totally independent of our ideal transmitting antenna. When Tesla spoke of the "Hertz wave" he was referring, in essence, to far-field electromagnetic radiation.

The type-one Tesla ‘antenna’ is also viewed as part of an electric dipole, consisting of the elevated capacitance, the helical resonator plus connections, and the earth itself. The aboveground portion is not intended as a source of electromagnetic radiation; rather, it is designed to minimize the production of electromagnetic radiation. [The working of the structure's helical resonator may be associated with a transverse magnetic wave. [Corum & Corum] and with an interaction with the Earth's magnetic field [Papadopoulos.] The principle that the ground acts as a mirror, which reflects electromagnetic energy radiated downward by the antenna mounted over it, is not applicable. The Tesla launching structure induces ground currents in the earth, and an associated surface wave. In the air path, electrical conduction through plasma and electrostatic induction take place. At the Wardenclyffe facility the ground consists of a 300-foot long vertical pipe driven downward from the bottom of a 120-foot deep shaft, making the maximum depth of the ground connection beneath the earth's surface 420 feet. [There have been differing interpretations of Tesla’s description of the underground portion of the tower, but this seems to be the best fit. [Personal conversation with Robert Uth.]

These are two examples of a type-one transmitter-receiver pair. The lower illustration shows some of the electric field lines associated with the flow of electrical energy between the transmitter and the receiver.

In tracing the flow of energy associated with the type-one transmitter a [phase conjugate] receiving structure has to be included in the circuit. This may be an identical oscillator configured as a receiver or passive helical resonator. The energy flowing between Tesla ground-air transmitter/receiver facilities is in the form of an electric current flowing through the earth between two ground connections plus an electric current flowing in plasma through an air path; electrostatic induction or so called ‘displacement currents’ can also be involved.

Conceptually, the type-two Tesla antenna structure is comprised of a basic type-one system including the receiving structure. Rather than being located at a great distance from the main transmitter oscillator (element A), the receiving structure (element B) is located close to the oscillator. The minimum spacing between the two structures might be equivalent to the wavelength of the element A oscillator frequency divided by 4. Element B is part of the transmitter circuit, and may be either an active type-one transmitter oscillator, or a passive top-loaded helical resonator connected to ground.

This illustration is an example of a type-two earth-resonance transmitter. A capacitively coupled plasma discharge is shown between the transmitter’s two elevated terminals. The receiving transformer shown to the right is not necessary for the transmitter to excite earth resonance.

The type-two transmitting circuit is used when employing the earth resonance method. It is designed specifically to produce a local flow of powerful currents in the earth between the two ground terminals. Electrical conduction through plasma takes place in the air path between the two elevated terminals. Each ground connection is modeled as a vertical pipe, at least 300 feet long, driven straight down from the bottom of a 120-foot deep shaft, for a minimum depth below the surface of 420 feet. The energy passing between elements A and B is in the form of an electric current through the earth between the two ground connections plus an electric current in plasma along the air path.

Preliminary Conclusion

The production of ground currents through the operation of a dipole in free space differs greatly compared with that of the ground current associated with the operation of both the type-one [and type-two Tesla apparatus]. In the first case, the current is induced by the refraction of space waves emitted from a distant transmitting antenna. In the second case an electric current is caused to flow through the earth between two specific, discreet, well-defined points on its’ surface. In this case the transmitted energy passes between the transmitter and receiver by a combination of electrical current flowing through the earth, and electrostatic induction and/or electrical conduction through plasma with an embedded magnetic field. Unlike the ½-wave dipole antenna, the type-one transmitter’s launching structure is not intended as a source of electromagnetic radiation; rather, it is designed to minimize the production of electromagnetic radiation. The principle that the ground plane acts as a mirror, which reflects electromagnetic energy projected downward by a ¼-wave monopole antenna mounted over it, is not applicable.

In both cases there is a surface wave. The space-wave induced current results in the production of the Norton surface wave according to the mechanism described above. When employing the Tesla apparatus, the electrical current flowing through the earth between the two elements induces the surface wave. In somewhat of a turnaround, the dissipation of electrical energy in the form of ground-current induced radio waves is viewed as loss in the Tesla system. Considering the vast difference in their manner of production it’s fair to ask: is this latter wave the Norton surface wave or something different?

Sommerfeld described an electrodynamic wave that is guided along a wire of finite conductivity and Zenneck expanded upon this description, asserting that the earth's surface performs in a manner similar to a conducting wire. And, while the Norton Surface Wave is the result of electrical currents induced in the ground by refraction of a portion of the reflected-wave component of the ground wave at the earth-atmosphere interface, we know the surface wave associated with Tesla’s apparatus is the result of electrical ground currents flowing between two points on the earth’s surface. Unlike the lossy Norton surface-wave that is excited by a conventional AM radio transmitter it would seem that Tesla’s surface wave would not diminish quite as significantly as the distance between the transmitting (or source) and receiving (or load) facilities increased. This is to be investigated.

Comparison of the Marconi Monopole and the Tesla Type-1 Launching Structures

At low frequencies, the Marconi system involves the excitation of a loading coil connected to an antenna wire. When everything is properly tuned, the antenna efficiently emits radio waves. These radio waves travel outward through the surrounding half space in every possible direction. A small fraction of the energy contained in these waves interacts with or is captured by the distant receiving antenna and detected and amplified using a radio wave receiver.

In contrast, the basic full-scale Tesla system consists of two mutually resonant transmitter/receiver facilities positioned a great distance from each other. Each facility uses transmitter/receiver circuitry consisting of, in part, a ground connection, a helical resonator and elevated terminal capacitance. The electrical energy produced by the two individual sources is conserved within and exists throughout the entire resonating system, including the earth itself. If only a single facility is in operation, acting as a transmitter in the absence of a receiver, then the transmitter will idle and no energy will be transmitted other than that which maintains the electrical vibration of the earth, counteracting the losses that occur in the form of electromagnetic radiation, radio waves, light and heat.

Not unlike the dipole Hertz antenna, the Marconi antenna is a source electromagnetic radiation in the form of space waves. Typically, these waves, that is to say the ground waves, take a direct or reflected path from the transmitter to the receiver. They may also be guided by the earth's surface as a ground-hugging Norton surface wave. The direct-wave component of the ground wave is limited only by the distance to the horizon from the transmitter plus a small distance added by atmospheric diffraction around the curvature of the earth. The ground-reflected component is the portion of the radiated wave that reaches the receiving antenna after being reflected from the Earth's surface. Prevailing wave propagation theory teaches that the surface-wave component is wholly the result of electrical currents induced in the ground by refraction of a portion of the reflected-wave component.

Upon reflection from the Earth's surface the reflected wave undergoes a 180 degree phase reversal. When both transmitting and receiving antennas are on, or close to, the ground, and the distance between them approaches the above-described limit, the direct and reflected components tend to cancel out, and the resulting field intensity is principally that of the surface wave. Because a part of its energy is absorbed by the ground, the electrical intensity of the surface wave is attenuated at a much greater rate than inversely as the distance. It is the conductivity of the underlying terrain that determines the attenuation of the surface-wave field intensity as a function of distance. The ground currents of a vertically polarized surface wave do not short-circuit a given electric field but rather serve to restore part of the used energy to the following field. The better the conducting surface, the more energy returned and the less energy absorbed. [ Antennas and Radio Propagation , TM 11-666, Dept. of the Army, Feb. 1953, pp. 17-23.]

Of course the Tesla antenna is also part of an electric dipole, consisting of the elevated capacitance, the helical resonator plus connections, and the Earth itself. As already discussed, the above-ground portion of the structure is not intended as a source of electromagnetic radiation, rather, it is designed, in part, to minimize the production of electromagnetic radiation. The principle that the ground acts as a mirror that reflects the electromagnetic energy radiated downward by the antenna mounted over it is not applicable. The Tesla launching structure induces ground currents in the earth, and an associated surface wave, which propagate the transmitted energy. This wave may be similar to the Zenneck surface wave. At the Wardenclyffe facility the ground consisted of a 300-foot long vertical pipe driven downward from the bottom of a 120-foot deep shaft, placing the maximum depth of the ground connection at 420 feet beneath the earth's surface. The elevated high voltage terminals of the transmitting and receiving stations are used to establish an interconnecting conducting path through the rarified upper level atmosphere.

The system Tesla described differs in many respects from the one implemented by Marconi. There are also distinct similarities.

Similarities:

In both cases the launching structure is associated with an electric dipole.

Both involve excitation of the dipole by an appropriate radio frequency power supply.

Both involve a ground connection and an electrically conducting aerial structure.

Differences:

Above ground launching structure geometry.

Hertz antenna, physically extended ½ wavelength from end to end; current and voltage are in phase.

Marconi antenna consists of a vertical conductor extending ¼ wavelength above the earth's surface [no loading coil and no capacitive top loading] and a counterpoise; current and voltage are in phase; common inductive and capacitive aerial elements.

Tesla antenna consists of a ¼ wavelength helical resonator with capacitive top loading – an elevated terminal of large surface area; inductive and capacitive and inductive elements are physically separated in space; entire structure a small fraction of ¼ wavelength in overall height. [What is the phase relationship between current and voltage on the structure?]

Power in antenna circuit modeled as parallel LC circuit

Hertz: alternately applied to opposing linear conductors; little reflected power due to high radiation resistance; voltage and current in phase resulting in development of production of E and H fields in phase shifting to quadrature phase relationship.

Marconi: alternately applied to aerial conductor and counterpoise; little reflected power due to high radiation resistance; voltage and current in phase resulting in the development of E and H fields in phase, shifting to quadrature phase relationship.

Tesla: alternately applied to top loaded resonator and ground; high reflected power due to low radiation resistance; do voltage and current exist in quadrature phase relationship on structure?.

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. [NTAC, pp.74-75]

Power supply waveform

Hertz/Marconi system: perfectly sinusoidal AC at oscillator frequency

Tesla system: dc pulse or square wave at oscillator frequency plus low frequency impulses of great intensity and short duration.

I reduced the number of poles, I think, in 1901. But then I reduced it for the purpose of generating currents of higher frequency. If I had a great number of poles, I could not realize my idea, because these poles would come in quick succession and not produce a rate of change comparable to the rate of change which is obtainable by the discharge of a condenser owing to a sudden break of the dielectric. That is to say, a blow. It has to be a blow, you see. I had to place my poles comparatively far apart, then run them at excessive speed and generate comparatively few impulses, but each of those impulses are of such tremendous intensity that the dynamo is practically short-circuited. That gave me a blow which replaced the arc. . . . [NTAC, p. 15]

Potential on structure

Marconi antenna, [say] 20 thousand volts

Tesla antenna, 10-100 million volts

Grounding system

Marconi antenna: ground consists of multiple [say 90 at four degree spacing] electrical conductors arranged radially and interconnected, 1/2 wavelength long, buried a short distance [6-8 inches] beneath the earth's surface. Alternatively, the ground portion can consist of a wire structure erected a short distance above the ground, and insulated from the Earth. Good ground conductivity is needed to reflect downward radiation. A good ground connection is only necessary to connect to the ‘mirror.’

“One common practice is to mount one half of a dipole vertically on a conducting surface (ground plane). This reduces the size of the aperture by 50%, resulting in a 3 dB loss. As we have seen, a dipole has 2.15 dB gain over an isotropic source; if a 1/4 wavelength antenna on a ground plane has 3 dB loss as compared to a dipole, that means that the "1/4 wave" antenna has 0.85 dB loss as compared to an isotropic source. Some antenna manufacturers express the gain of their products as "gain over a 1/4 wave". An antenna advertized as having 3 dB gain over a 1/4 wave is the same as as an antenna having 2.15 dBi gain or 0 dBd gain. It's the same antenna - the bigger numbers are just that - bigger numbers!

“A somewhat less common practice is to mount a vertical dipole directly on the ground. This practice is fraught with problems. A portion of the aperture is beneath the ground. This induces large currents into the ground surrounding the antenna. With the high (and uncontrollable) ground resistance, these currents result in substantial voltage drops. The power lost to heating the ground does nothing more than make the worms uncomfortable. These losses can be reduced to acceptable levels by installing an extensive ground system. The severe aperture interference also causes the antenna to exhibit a high angle of radiation. It would be easier (and cheaper) to elevate the antenna far enough so that the aperture does not touch the ground.” [http://k9erg.tripod.com/theory.htm]

Tesla antenna: ground consists of a deeply buried conductor. At the Wardenclyffe facility the ground consisted of a 300-foot long vertical pipe driven downward from the bottom of a 120-foot deep shaft. [NTAC p. 203]

Operating frequency

Marconi / Hertz system: 8 kHz – 100 gHz

Tesla system: fundamental Earth resonant frequency, say 7.5 Hz + 975 Hz to 30 kHz + higher harmonics extending up to 100 gHz

Excitation of propagating medium

Marconi antenna / half-wave dipole, the electric field energy and the magnetic field energy are introduced into the field medium in time-phase with each other. The excitation of the medium by the antenna develops an in phase propagation mode shifting to a quadrature phase propagation mode, this taking place over the initial range of transmission; Fresnel zone, also called the radiating near field. The launching structure provides a good initial impedance match with free space resulting in the efficient production of electromagnetic waves.

Tesla antennas, electric current in lower half-space; TM surface wave, spiraling electrostatic and magnetic flux lines in dielectric portion of upper half-space; electric current and magneto-hydrodynamic waves in ionized portion of upper half-space. The 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 ionizing and breaking down the denser insulating portions of the earth's atmosphere around and above it, rendering this medium electrically conducting.

Energy flow

Marconi system involves the passage of energy in a single direction.

Tesla system permits two-way passage of electromagnetic energy.

Additional

Hertz/Marconi: Discrete transmitters and receivers

Tesla: Conjugate transmitter/receiver installations; Floating grounds for energy storage; transmitted wave is in higher order group symmetry form; 3-wave, 4-wave . . . n-wave mixing; permits parametric pumping without auxiliary power input source.

Propagation mode

Hertz/Marconi: Electromagnetic radiation (Space wave), ground wave (direct, reflected, and Norton surface wave) and reflected sky wave.

Tesla: electrical conduction, earth currents and associated surface wave; air path by conduction in plasma and electrostatic induction. In Tesla’s words,

“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, 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 cannot travel along this curve and get there, but 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.”

Tesla asserted the propagation mode was dependent upon transmitter design and operating frequency.

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 wavelengths, 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 [earth] 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. . . . [NTAC, p. 132]

In radio, the transmitter and receiver function independently of each other. The transmitting element, in the case of the Marconi antenna, consists of a vertical single-linear-wire conductor having both inductance and capacity, and a corresponding ground-plane image. The receiving element is also a single linear wire electrical conductor having both inductance and capacity. The transmitter emits an electromagnetic wave, which separates itself from the antenna and radiates outward. The receiving antenna intercepts a portion of this wave, the energy of which is detected and utilized. The net energy flow is in one direction, away from the antenna. The energy moves away from transmitter to receiver, with the connection being made through the space above the earth’s surface. The earth is not necessary for the system to work.

In Tesla’s system the transmitter and receiver are interdependent. The transmitting element consists of three sub-elements, a single coiled wire conductor—a helical resonator—possessing inductance, and two conducting bodies of large surface area in relationship to their greatest linear dimension, which have a mutual electrical charge storage capacity. One of these bodies is the elevated terminal positioned above the resonator. The other body is the earth itself. The receiving element also consists of three sub-elements, a helical resonator and two conducting bodies of capacitance, one of which is an elevated. As with the transmitter, the other body is the earth. It is this common conducting body, which forms the ground connection between the transmitter and receiver through which alternating electric current flows. The other connection required to form a closed circuit is through the air by electrical conduction in plasma and electrostatic induction. The movement of energy is in both directions, from the transmitter to the receiver and visa versa.

In 1916 Nikola Tesla cited the 1909 analysis of mathematician Arnold N. Sommerfeld to support his explanations of observed radio phenomena. Sommerfeld’s analysis shows that an electromagnetic wave can be guided along a wire of finite conductivity. (Corum & Corum) [note: the Sommerfeld analysis has been disputed]. Two years earlier Johann Zenneck had mathematically modeled a surface wave that travels along the interface between the ground and the air. “Zenneck conceived that the earth's surface would perform in a manner similar to a single conducting wire. The distinguishing feature of the Zenneck wave is that the propagating energy doesn’t spread like radiation, but is concentrated near the guiding surface.” (Corum & Corum) In commenting on Sommerfeld's analysis of the surface wave, Dr. James R. Wait stated, "The field amplitude varies inversely as the square root of the horizontal distance from the source. . . ." Sommerfeld made a point of distinguishing between the "electrodynamic" surface wave and its Hertzian counterpart the space wave.

[See also “Operating Principles of the Wardenclyffe Apparatus” http://www.tfcbooks.com/teslafaq/q&a_038.htm.]

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Ground Current Comparison

Comparing the effects of the current that flows through the surrounding environment between the air and ground terminals of the two Tesla transmission systems with that which results from the current in the antenna of a VLF radio transmitter, are these the same phenomenon? Take for example two optimized transmitters, one using an ideal Marconi antenna incorporating a ‘counterpoise’ structure and the other a type-one Tesla transmission system. In the first case a large fraction of the energy resonating within the antenna circuit is carried away in the form of radio waves, a minute fraction of which can be recovered by a distant receiver. In the second, the physical conductors—the transmitting and receiving apparatus, earth, and conducting atmospheric strata—of which the system is composed—conserve the bulk of the energy. In the second case losses are associated with the unintentional creation of incidental electromagnetic radiation.

Regarding the flow of ground current,

Whether this current passing through the center of the earth to the opposite side is real, or whether it is merely an effect of these surface currents, makes absolutely no difference. To understand the concept, one must imagine that the current from the transmitter flows straight to the opposite point of the globe.

There is where I answer the attacks which have been made on me. For instance, Dr. Pupin has ridiculed the Tesla system. He says,

"The energy goes only in all directions."

It does not. It goes only in one direction. He is deceived by the size and shape of the earth. Looking at the horizon, he imagines how the currents flow in all directions, but if he would only for a moment think that this earth is like a copper wire and the transmitter on the top of the same, he would immediately realize that the current only flows along the axis of the propagation. [NT on AC]

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Electromagnetic Radiation vs. Electrical Conduction

Counsel

You say radio engineers put too much energy into the radiating part. What, as a matter of fact, according to your conception, is the part of the energy that is received in the receivers in the present system?

Tesla

That has been investigated. Very valuable experiments have been made by Dr. Austin, who has measured the effects at a distance. He has evolved a formula in agreement with the Hertz wave theory, and the energy collected is an absolutely vanishing quantity. It is just enough to operate a very delicate receiver. If it were not for such devices as are now in use, the audion, for instance, nothing could be done. But with the audion, they magnify so that this infinitesimal energy they get is sufficient to operate the receiver. With my system, I can convey to a distant point millions of times the energy they transmit. [NTAC]

Six orders of magnitude difference in transmission loss; Tesla must have made real-world physical measurements in support of this statement.

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The Norton and Zenneck Surface Waves

While the Zenneck Surface Wave and the Norton Surface Wave are both examples of surface-wave phenomena, the mechanisms behind their production are quite different. An electrical oscillator or radio-frequency power supply can be configured in a way that is conducive to the production of either type of surface wave. The principle differences are in the geometry of the elevated conductor and the construction of the ground terminal connection, or ground plane/counterpoise structure.

Tesla said,

This illustrates, on a larger scale, the earth. Here is my transmitter—mine or anybody's transmitter—because my system is the system of the day. The only difference is in the way I apply it. They, the radio engineers, want to apply my system one way; I want to apply it in another way.

This is the circuit energizing the antenna. As the vibratory energy flows, two things happen: There is electromagnetic energy radiated and a current passes into the earth. The first goes out in the form of rays, which have definite properties. These rays propagate with the velocity of light, 300,000 kilometers per second. This energy is exactly like a hot stove. If you will imagine that the cylinder antenna is hot—and indeed it is heated by the current—it would radiate out energy of exactly the same kind as it does now. If the system is applied in the sense I want to apply it, this energy is absolutely lost, in all cases most of it is lost. While this electromagnetic energy throbs, a current passes into the globe.

Now, there is a vast difference between these two, the electromagnetic and current energies. That energy which goes out in the form of rays, is, as I have indicated here, unrecoverable, hopelessly lost. You can operate a little instrument by catching a billionth part of it but, except this, all goes out into space never to return. This other energy, however, of the current in the globe, is stored and completely recoverable. Theoretically, it does not take much effort to maintain the earth in electrical vibration. I have, in fact, worked out a plant of 10,000 horsepower which would operate with no bigger loss than 1 percent of the whole power applied; that is, with the exception of the frictional energy that is consumed in the rotation of the engines and the heating of the conductors, I would not lose more than 1 percent. In other words, if I have a 10,000 horsepower plant, it would take only 100 horsepower to keep the earth vibrating so long as there is no energy taken out at any other place. [NT on AC, p. 140]

If Tesla was right, low frequency wireless communications can be accomplished by the production of either electromagnetic radiation in the form of space wave induced ground currents and an accompanying electromagnetic wave called the Norton surface wave, or the production of a pulsed magnetic field, high energy plasma phenomena, and ground currents at the transmitter, resulting in an accompanying trapped surface-wave bearing a resemblance to the Zenneck surface wave.

This is a low frequency transverse magnetic surface wave that travels along the interface between the ground and the air, in which the propagating energy does not radiate into space but is concentrated near the guiding surface. These waves do not contribute significantly to the field produced by a conventional dipole or quarter-wave radiator, however they can be strongly excited by a quarter-wave helical resonator positioned within a resonant cavity. [Corum & Corum]

To once again to quote 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.



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, ["Propagation of Waves in Wireless Telegraphy," Arnold N. Sommerfeld, Ann. Phys. (Leipzig), 28, 1909, pp. 665-737.] 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." [Nikola Tesla On His Work With Alternating Currents and Their Application to Wireless Telegraphy, Telephony and Transmission of Power; see also A Comparison of Tesla and Marconi Low Frequency Wireless Systems]

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Appendix

Antenna Theory and Impedance Matching

A radiating electromagnetic field is due to a collection of charged particles, specifically electrons, oscillating in an electrical conductor. Such a conductor comprises a radio-wave launching structure. The charge is forced into oscillation by the injection of electrical energy from a source such as a battery or electrical generator. The injection process involves impedance matching of the energy source and the launching structure, as well as the transmission line that connects the two. While the true structure of the electron is not known, it is viewed as being a small sphere with an electrical charge evenly distributed over its surface. Along with the charge is an electric field known as the Coulomb field that points outward from the electron in all directions. When in set into motion, an electron becomes surrounded by a circular magnetic field. When an electron is made to accelerate or decelerate an additional electric field component called the dynamic electric field arises. The dynamic electric field component itself can be regarded as being comprised of two additional field components. The overall field intensity of these additional field components is their vector sum. The first, the radiation field component, exists in phase with the magnetic field. This means that the radiation field increases in intensity simultaneously with the increase of intensity of the magnetic field. The other dynamic electric field component, the induction field, is out of phase with the magnetic field, lagging behind it by a phase angle of 90deg.

In oscillation this energy is traded 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 “Why an Antenna Radiates,” http://www.abelian.demon.co.uk/tesla-notes/030802.html, Teaching Electromagnetism Using Advanced Technologies].

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Capacity of an Elevated Sphere

“The self-capacitance of a spherical conductor is proportional to its radius, and is 111 pF or micro-micro farads per metre of radius.” [Henry Bradford]

Tesla’s Colorado Springs investigations led him to the conclusion that the capacitance of an elevated terminal is not constant, but increases with elevation.

Exactly as mechanics and engineers have taken it for granted that the pliability of the spring remains the same, no matter how it be placed or used, so electricians and physicists have assumed that the electrostatic capacity of a conducting body, say of a metallic sphere, which is frequently used in experiments, remains a fixed and unalterable quantity, and many scientific results of the greatest importance are dependent on this assumption. Now, I have discovered that this capacity is not fixed and unalterable at all. On the contrary, it is susceptible to great changes, so that under certain conditions it may amount to many times its theoretical value, or may eventually be smaller. . . . Continuing the investigation of this astonishing phenomenon I observed that the capacity varied with the elevation of the conducting surface above the ground and I soon ascertained the law of this variation. The capacity increased as the conducting surface was elevated, in open space, from one-half to three-quarters of 1 percent per foot of elevation. In buildings, however, or near large structures, this increase often amounted to 50 percent per foot of elevation, . . . [38b]

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Ground Current Behavior

Tesla speculated about the behavior of the ground currents involved in the operation of the system.

There is another difference. The electromagnetic energy travels with the speed of light, but see how the current flows. At the first moment, this current propagates exactly like the shadow of the moon at the earth's surface. It starts with infinite velocity from that point, but its speed rapidly diminishes; it flows slower and slower until it reaches the equator, 6,000 miles from the transmitter. At that point, the current flows with the speed of light—that is, 300,000 kilometers per second. But, if you consider the resultant current through the globe along the axis of symmetry of propagation, the resultant current flows continuously with the same velocity of light.

Whether this current passing through the center of the earth to the opposite side is real, or whether it is merely an effect of these surface currents, makes absolutely no difference. To understand the concept, one must imagine that the current from the transmitter flows straight to the opposite point of the globe.

There is where I answer the attacks which have been made on me. For instance, Dr. Pupin has ridiculed the Tesla system. He says,

"The energy goes only in all directions."

It does not. It goes only in one direction. He is deceived by the size and shape of the earth. Looking at the horizon, he imagines how the currents flow in all directions, but if he would only for a moment think that this earth is like a copper wire and the transmitter on the top of the same, he would immediately realize that the current only flows along the axis of the propagation.

The mode of propagation can be expressed by a very simple mathematical law, which is, the current at any point flows with a velocity proportionate to the cosecant of the angle which a radius from that point includes with the axis of symmetry of wave propagation. At the transmitter, the cosecant is infinite; therefore, the velocity is infinite. At a distance of 6,000 miles, the cosecant is unity; therefore, the velocity is equal to that of light. This law I have expressed in a patent by the statement that the projections of all zones on the axis of symmetry are of the same length, which means, in other words, as is known from rules of trigonometry, that the areas of all the zones must also be equal. It says that although the waves travel with different velocities from point to point, nevertheless each half wave always includes the same area. This is a simple law, not unlike the one which has been expressed by Kepler with reference to the areas swept over by the radii vectors.

I hope that I have been clear in this exposition—in bringing to your attention that what I show here is the system of the day, and is my system—only the radio engineers use my apparatus to produce too much of this electromagnetic energy here, instead of concentrating all their attention on designing an apparatus which will impress a current upon the earth and not waste the power of the plant in an uneconomical process. [NTAC]

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Nikola Tesla’s Priority in the Invention of Radio

As stated in the book Tesla - Master of Lightning , “The question of who invented radio, and when, and what defines the invention, have sparked fierce debates that still continue.” Re-reading the chapter in question I found one assertion that perhaps should be revised. On page 66 one of the authors writes, "Tesla, in fact, thought that Hertz had misinterpreted the results of his experiment. Tesla believed that radio signals were induced by earth currents, not air waves."

On the contrary, Tesla fully acknowledged the existence of “air waves.”

It was a perfectly well-established fact that a [dipole] circuit, traversed by a periodic current, emitted some kind of space waves. . . .

Tesla goes on to state,

As regards signaling without wires, the application of these radiations for the purpose was quite obvious. When Dr. Hertz was asked whether such a system would be of practical value, he did not think so, and he was correct in his forecast. The best that might have been expected was a method of communication similar to the heliographic and subject to the same or even greater limitations. [The True Wireless]

Needless to say, Tesla was somewhat off the mark with that prediction.

His fundamental disagreement lay in the model used to describe the physical process that takes place within the propagating medium. Hertz had described this as transversal vibrations in the ether. Tesla’s model differed from Hertz’s in that propagation is described as being by compression and rarefaction of the propagating medium, similar to acoustic waves traveling through gas.

The assumption of the Maxwellian ether was thought necessary to explain the propagation of light by transverse vibrations, which can only occur in a solid. So fascinating was this theory that even at present it has many supporters, despite the manifest impossibility of a medium, perfectly mobile and tenuous to a degree inconceivable, and yet extremely rigid, like steel. As a result some illusionary ideas have been formed and various phenomena erroneously interpreted. The so-called Hertz waves are still considered a reality proving that light is electrical in its nature, and also that the ether is capable of transmitting transverse vibration of frequencies however low. This view has become untenable since I showed that the universal medium is a gaseous body in which only longitudinal pulses can be propagated, involving alternating compressions and expansions similar to those produced by sound waves in the air. Thus, a wireless transmitter does not emit Hertz waves which are a myth, but sound waves in the ether, behaving in every respect like those in the air, except that, owing to the great elastic force and extremely small density of the medium, their speed is that of light. [Pioneer Radio Engineer Gives Views on Power, New York Herald Tribune, September 11, 1932]

In our present physical model the closest analogous description we have to this “universal medium” is plasma—often referred to as the fourth state of matter. It has been suggested that plasma should be called the first state of matter, as it is plasma of which about 99% of the known universe is composed. [Plasma Dictionary: Plasma]

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Tesla’s Early Wireless Work

It is a little known fact that Tesla used his high voltage resonance transformer—the Tesla coil—in radio wave propagation experiments. In his words,

The popular impression is that my wireless work was begun in 1893, but as a matter of fact I spent the two preceding years in investigations, employing forms of apparatus, some of which were almost like those of today. . . .[The True Wireless]

After a while he began to favor another technique that he called the “air-ground method.” He used the same basic apparatus, however instead of using electromagnetic space waves, the energy is carried by conduction of electrical currents through the earth and accompanying surface waves. For a type-1 transmission system the ‘return’ path closing the circuit is an electrical current flow established between two elevated terminals, one belonging to the transmitter and the other the receiver. These consist of true conduction currents flowing through plasma and also electrostatic induction. The Wardenclyffe plant was designed to operate on this principle.

. . . It was clear to me from the very start that the successful consummation could only be brought about by a number of radical improvements. Suitable high frequency generators and electrical oscillators had first to be produced. [This work is discussed above.] The energy of these had to be transformed in effective transmitters and collected at a distance in proper receivers. Such a system would be manifestly circumscribed in its usefulness if all extraneous interference were not prevented and exclusiveness secured. In time, however, I recognized that devices of this kind, to be most effective and efficient, should be designed with due regard to the physical properties of this planet and the electrical conditions obtaining on the same. . . . [The True Wireless]

Tesla’s pioneering contribution to radio technology was a reworking of the primitive Hertz spark-gap transmitter; introduction of the coupled tuned circuit with the energy storage capacitor and discharger repositioned to the primary side of the transformer. [Kenneth and James Corum] This is the classic Tesla coil configuration, with primary and secondary circuits tuned to vibrate in harmony. These modifications allowed significantly higher levels of radio-frequency energy to be concentrated into a damped or partially damped wave, and ultimately a practically undamped wave. Some historians credit Reginald Fessenden in 1900 for making these improvements. Others credit Adolph Slaby. Still others say it was Ferdinand Braun, in a hastily improvised demonstration performed in September 1898. Braun, together with Marconi, received the Nobel Prize in physics for this replication of Tesla’s discovery.

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Tesla’s circuit diagram from the 1891 U.S. Patent "System of Electric Lighting" shows an energy storage capacitor and discharger on the primary side of a radio-frequency power-supply transformer. This is the first-ever disclosure of a practical high power radio-frequency power supply. It represents a device that is capable of exciting an antenna to emit powerful electromagnetic radiation.

Actually, it was Nikola Tesla who first revealed the basic techniques for improving transmitter performance. He did this in a series of U.S. patents, starting with his "System of Electric Lighting," Patent No. 454,622, dated June 23, 1891, the accompanying drawing of which clearly shows an energy storage capacitor and a discharge device on the primary side of a resonance transformer. In1893 at a public meeting of the National Electric Light Association in St. Louis, this radio-frequency power supply circuit was used to demonstrate the world's first practical radio transmitter.

"In the transmitter group on one side of the stage was a 5-kva high-voltage pole-type oil-filled distribution transformer connected to a condenser bank of leyden jars, a spark gap, a [Tesla] coil, and a wire running up to the ceiling.



"In the receiver group at the other side of the stage was an identical wire hanging from the ceiling, a duplicate condenser bank of Leyden jars and coil—but instead of the spark gap, there was a Geissler tube that would light up like a modern fluorescent lamp bulb when voltage was applied. There were no interconnecting wires between transmitter and receiver." [ Tesla-Man Out of Time]

His patent "Means for Generating Electric Currents" No. 514,168 of February 6, 1894 describes a variation of the 1891 circuit. Between September 15, 1896 and November 18, 1898 no fewer than 17 patents were granted to Tesla for apparatus and methods directly related to the production of high power radio-frequency electrical currents. It was during that same period, on September 2, 1897, that Tesla filed his first application which was directly related to wireless transmission and reception, resulting in two patents that were subsequently issued as System of . . ." and "Apparatus for Transmission of Electrical Energy," dated March 20 and May 15, 1900 respectively. On July 1, 1898 another wireless-related application was filed for the radio-controlled boat resulting in the patent, "Method of and Apparatus for Controlling Mechanism of Moving Vessels or Vehicles" issued November 8, 1898. He also developed receivers incorporating two tuned circuits. Between 1898 and 1903 Tesla received 10 U.S. patents covering his work in this area.

In 1904 Marconi got his own patent, declaring principles that Tesla had developed. The issue of patent infringement by Marconi was addressed in a lawsuit brought by Tesla in 1915. Nothing significant resulted from this litigation and shortly thereafter the Marconi Wireless Telegraph Company of America itself sued the United States for alleged damages resulting from the use of wireless during WWI. In response, a 1935 ruling by the United States Court of Claims essentially invalidated the fundamental Marconi patent. It was decided that the basic apparatus associated with radio communications had, in fact, been anticipated by Tesla. The U.S. Supreme Court affirmed this finding on June 21, 1943. The following definition of radio emerged as a result of this case:

A radio communication system requires two tuned circuits each at the transmitter and receiver, all four tuned to the same frequency. [Marconi Wireless Telegraphy Company vs. United States]

Additional reading:

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Investigation of Tesla-Type Wireless Propagation [mathematical modeling and physical validation]

After all this there is still the unanswered question, exactly how does the Tesla system work? It appears that early on Tesla himself was somewhat unsure. This especially seems to be the case when construction of the Wardenclyffe facility began. If the laws of physics, and operational parameters of his apparatus were known with mathematical certainty he would not have made the critical design errors alluded to in a 1903 letter to J.P. Morgan. [Wardenclyffe and the World System : The history and design of Nikola Tesla’s wireless telecommunications facility on Eastern Long Island]

He made observations and collected data, but given the primitive state of plasma physics at the time, it would have been difficult if not impossible for him to properly explain what was actually taking place. [See The Generation of Plasma Waves at the Earth's Surface for Telecommunications Purposes.]

Employ mathematical analysis.

Know the difference between facts and assumptions.

Exhibit a balance between theory and experiment.

Validate the technology through testing.

Present day electromagnetic theory based upon Maxwell’s Equations. Undamped wave equation, Laplace-Operator can be decomposed into two parts, scalar and vector. [“Electric Scalar Waves – Review to Meyl’s Experiment,” “Elektrische Skalarwellen” - Review zum Meyl'schen Experiment, André Waser. See also Nikola Tesla’s Wireless Systems.]

Negative solution to Maxwell’s Equations allows creation of a magnetic field without current flow in wire. [Maurice Hately & Fathl Kabbary, 1995

Longitudinal Waves Waves where the variation of the field is partially or totally in the direction of propagation (parallel to wavennumber, k [a vector]. Examples include sound waves and Langmuir waves. Contrasted with transverse waves, where the variation is perpendicular to the direction of propagation, such as light waves.

Plasma Known as the "Fourth State of Matter", a plasma is a substance in which many of the atoms or molecules are effectively ionized, allowing charges to flow freely. Since some 99% of the known universe is in the plasma state and has been since the Big Bang, plasmas might be considered the First State of Matter. Plasmas have unique physics compared to solids, liquids, and gases; although plasmas are often treated as extremely hot gases, this is often incorrect. Examples of plasmas include the sun, fluorescent light bulbs and other gas-discharge tubes, very hot flames, much of interplanetary, interstellar, and intergalactic space, the earth's ionosphere, parts of the atmosphere around lightning discharges, laser-produced plasmas and plasmas produced for magnetic confinement fusion. Types of plasmas include - Astrophysical, Collisionless, Cylindrical, Electrostatically Neutral, Inhomogeneous, Intergalactic, Interstellar, Magnetized, Nonneutral, Nonthermal, Partially Ionized, Relativistic, Solid State, Strongly Coupled, Thermal, Unmagnetized, Vlasov and more.

Plasma Wave A disturbance of a plasma away from equilibrium, involving oscillations of the plasma's constituent particles and/or the electromagnetic field. Plasma waves can propagate from one point in the plasma to another without net motion of the plasma. Terms used to describe the many kinds of waves in plasmas include: Alfven, Circularly Polarized, Cold Plasma, Drift, Electromagnetic, Electron-Cyclotron, Electron Plasma, Electrostatic, Electrostatic Ion, Electrostatic Ion Cyclotron, Evanescent Extraordinary, Ion-Acoustic, Ion Cyclotron, Ion Plasma, Ion Sound, Langmuir, Left Circularly Polarized, Light, Longitudinal, Lower Hybrid, Magnetohydrodynamic (MHD), Magnetosonic, Negative Energy, Nonlinear, Ordinary, Parallel, Perpendicular, Plane, Radio, Right Circularly Polarized, Shock, Space-Charge, Transverse Travelling, Unmagnetized, Upper-Hybrid, Vlasov, Whistler.

Plasma Oscillations Class of electrostatic oscillations which occur at/near the plasma frequency (see entry) and involve oscillations in the plasma charge densities. These modes are also known as Langmuir oscillations or Langmuir waves; in Stix's _Waves in Plasmas_ they are more properly called Langmuir-Tonks Plasma Oscillations.

Ion acoustic wave A longitudinal compression wave in the ion density of a plasma. For more information see (e.g.) Stix, Thomas Howard. _Waves in Plasmas_, American Institute of Physics, New York, 1992.

Soliton Solitons, or solitary waves, are stable, shape-preserving and localized solutions of nonlinear classical field equations, where the nonlinearity opposes the natural tendency of the solution to disperse. They were first discovered in water waves, and there are several hydrodynamic examples, including tidal waves. Solitons also occur in plasmas. One example is the ion-acoustic soliton, which is like a plasma ``sound'' wave; another is the Langmuir soliton, describing a type of large amplitude (nonlinear) electron oscillations. Solitons are of interest for optical fiber communications, where it has been proposed to use optical envelope solitons as information carriers in fiber optic networks, since the natural nonlinearity of the optical fiber may balance the dispersion and enable the soliton to maintain its shape over large distances.]

Note: The C/S structure resembles a “conventional” antenna, with a subsequent shift to the prototypical launching structure at Wardenclyffe.

Possible side effects related to system operation:

Ozone production

Static electricity effects

Electrostatic induction is a better term than dielectric displacement current.

Oscillating dipoles in dielectric medium

What dipoles in the classical vacuum?

Phase conjugation

Phase velocity

Spread spectrum frequency division multiplexing

Channels at 7.8 Hz increments [Corum & Corum]

Top-turn primary of large C/S oscillator pulse-driven by alternator to produce ELF component. (Corum & Corum)

While at C/S Tesla considered or investigated at least 125 different variations of receiver design. [Tesla's Synchronized Receiving Apparatus]

N.T. Museum for information on patents-not-granted application filings, ca. 1900-1902

High-speed break or circuit controller

RF alternator

High-voltage mechanical rectifier

High power solid-state switch and a signal generator

More on Tesla coils . . .

Master oscillator tuning corresponds with resonant frequency of the top loaded resonator.

The secondary winding length should be approximately ____% of the operating frequency wavelength.

Analyze C/S data for secondary length / resonator frequency relationship

Tesla said the transformer should be tuned to avoid the beat.

Transformer increases voltage, and introduces series inductance. Does this relate to the development of a wave complex?

Is this for an isotropic capacitance, i.e., the smaller of two concentric conducting spheres with larger sphere taken out to infinity?

Is this an accurate statement for real-world conditions?

Influence of elevation upon capacity?

Influence of environment in general upon capacity?

Attempt to mathematically describe what Tesla was claiming about his system.

Precise performance data would be useful in formulating a solution.

Formulate a boundary-value solution for the helical resonator.

Helical resonator is not an antenna loading coil.

The earth as a transmission line

Validate antenna theory, i.e. real-world model of the production of electromagnetic radiation, without speaking of the isotropic radiator as if it actually exists in the real world. Or does it exist?

Electrostatic induction between elevated capacitance and Earth’s surface. [Wasser]

Electrostatic induction between elevated capacitances.

Magnetic coupling or mutual induction between distant helical resonators.

Capture area exceeds physical dimensions of receiving structure & reciprocity with launching structure.

Near field or quasi-near field conditions throughout global network.

Mathematical description of vertical dipole antenna in free space?

Mathematical description of Marconi antenna?

Mathematical description of type-one Tesla antenna?

Mathematical description of type-two Tesla antenna?

Are all four electrically equivalent?

Follow the energy: If the Marconi antenna differs from the Tesla antenna in the production of electromagnetic radiation, were does the energy go in the latter case, i.e., how is the energy dissipated in the Tesla systems?

Incorporate multiple single terminal vacuum tubes in construction of the elevated terminals, as disclosed in teleforce disclosure.

Derive some impressions from the “Oscillator Shuttle Circuit” patent disclosure.

Treating the Marconi antenna as the equivalent of a half-wave dipole, the electric field energy and the magnetic field energy are introduced into the field medium in time-phase with each other. The excitation of the medium by the antenna develops a “forced propagation mode,” degenerating into “natural mode propagation” with energy dissipation taking place over an initial range of transmission. In contrast, the Tesla launching structure is so configured that . . . the electric and magnetic fields are set up in quadrature phase, i.e., a 90deg phase shift as compared to dipole, corresponding to the natural propagation mode of the field medium. [Gieskieng Antenna, An Antenna With Anomalous Radiation Properties, Harold Aspden, 1987, 1998]

“Slaby improved the equipment, as transmitter served now a spark coil, whose spark gap did not lie in the transmitting antenna - as with Marconi -, but in a circle coupled inductively with the circuit of antennas. Independently of Slaby the physicist Ferdinand Braun in Strasbourg worked on radio systems. It was first, that had really understood, what with Marconi‘s devices electrically took place. From theoretical considerations Braun came to the conclusion to couple the spark gap with the transmitter inductively (resonant circuit, 1898) and also the coherer inductively to the antenna to couple. For this basic concept Braun received the Nobel Prize, together with Marconi.”

Search phrases:

dipole antenna "antenna theory" physics

model

“NEC software”

"EH Antenna"

Search results:

NEC software is based on a solution of Maxwell's Equations. For wire types of structures, it solves Maxwell's Equations using the Electric Field Integral Equation. For surface types of structures, it solves them using the Magnetic Field Integral Equation. The program is capable of solving complicated structures. Its accuracy and limitations are well documented in the scientific literature, and it can easily solve a fairly simple antenna structure.

“Maxwell's Equations are considered an exact solution for electromagnetic radiation.” (?)

"The phasing network aligns the relative phase between the current and the voltage of the radio frequency power signal so that the H-field component of the corresponding electromagnetic signal is nominally in time phase with the E-field component".

This is exactly what happens in every antenna and is called the Poynting vector.

If the E and H fields are not in time alignment, the antenna will not radiate.” (?)

The power feeding your antenna is going to one or more of the following places:

- Radiation from the antenna

- Power dissipation in the antenna

- Power dissipation in the matching network

- Radiation from the coax

- Power dissipation in the coax

- Power dissipation in the transmitter (most people don't realize that transmitters can dissipate power that is not radiated by the antenna)

You will need to do a carefully controlled set of experiments to determine where the power is going in your setup. E-H Antenna Simulation in NEC

End Notes

1. Norton surface wave The ground-wave component of a space wave resulting from refraction of a portion of the reflected-wave component at the Earth-atmosphere interface and induction of electrical currents in the ground. Upon reflection from the Earth's surface the reflected wave undergoes a 180deg phase reversal. When both transmitting and receiving antennas are on, or close to, the ground, and the distance between them becomes great, the direct and reflected components tend to cancel out, and the resulting field intensity is principally that of the surface wave. Because part of its energy is absorbed by the ground, the electrical intensity of the surface wave is attenuated at a much greater rate than inversely as the distance. It is the conductivity of the underlying terrain that determines the attenuation of the surface-wave field intensity as a function of distance. The ground currents of a vertically polarized surface wave do not short-circuit a given electric field but rather serve to restore part of the used energy to the following field. The better the conducting surface layer, the more energy returned and the less energy absorbed.

2. Zenneck surface wave A low frequency transverse magnetic surface wave that travels along the interface between the ground and the air, in which the propagating energy does not radiate into space but is concentrated near the guiding surface. These waves do not contribute significantly to the field produced by a conventional dipole or quarter-wave radiator, however they can be strongly excited by a grounded quarter-wave helical resonator. See slow-wave helical resonator and magnifying transmitter.



Geometry for Zenneck wave propagation.



The complex longitudinal propagation phase constant along the Earth's surface.





Zenneck wave field strength decrease for around-the-world propagation as a function of frequency in kHz. [*]

· Corum, K. L. and J. F. Corum, "The Zenneck Surface Wave," Appendix II of "Nikola Tesla, Lightning Observations, and Stationary Waves," 1994.

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Kirchoff's Laws and their application to direct current (DC) circuits

Kirchoff's Laws describe the behavior of electrical currents flowing in direct current (DC) electrical circuits. DC circuits consist of one or more voltage sources connected to one or more of the following: resistors, capacitors and inductors.

A simple DC circuit consisting of a DC source and a single resistor

Kirchoff's 1st Law states that the current flowing into a junction in a circuit (or node) must equal the current flowing out of the junction. This law is a direct consequence of the conservation of charge. Since no charge can be lost in the junction, any charge that flows in must ultimately flow out. Kirchoff's 1st Law can be remembered as the rule that uses nodes to study the flow of current around a circuit.

Kirchoff's 2nd Law This law states that for any closed loop path around a circuit the sum of the voltage gains and voltage drops equals zero. In the circuit shown, there is a voltage gain for each electron traveling through the voltage source (symbolized by ) and a voltage drop across the resistor ( iR). Applying Kirchoff's law:





Note that this result has the same form as Ohm's law:





Kirchoff's 2nd Law is based on the principle of conservation of energy. No energy can be lost from or gained by the circuit, so the net voltage change must be 0. Kirchoff's 2nd Law can be remembered as the rule that uses loops to study the flow of current around a circuit. [Source: http://www.scientia.org/cadonline/Physics/circuits/kirchoff.ASP, see also http://www.scientia.org/cadonline/Physics/circuits/home.ASP.]

A simple RC circuit consisting of a DC source, a resistor and a capacitor

To solve the circuit when it is charging , Kirchoff's second law is applied:

Both i and q are time dependent, so another linearly independent equation is needed to solve the circuit. This equation shows the relation between i and q :

A way to understand this equation is to consider a plot of q(t) vs. t. The slope of the curve at the point [t,q(t)] equals the current i(t) at time t .

Solving (1) and (2) requires an understanding of differential and integral calculus, so only the solutions are given:

Plots of these functions are shown. Note that the charge of the capacitor increases from an initial value of 0 to a maximum value of C . This increase is the reason why the RC circuit is said to be charging. Simultaneously, the current flow decreases from an initial value of - /R to a minimum value of 0. Current ceases to flow when the capacitor is fully charged.

The RC circuit can be discharged only after it has been charged. In the following example, it is assumed that the capacitor is fully charged. Therefore, just before the switch is thrown to disconnect the power supply,

From Kirchoff's second rule,

Again, the relation between i and q is necessary to solve,

Working through the calculus,

Plots of these functions are shown . Note that the charge of the capacitor decreases from an initial value of - /R to a minimum value of 0. This decrease is the reason the RC circuit is said to be discharging. Simultaneously, the current flows with maximum magnitude initially C (but in the opposite direction as in the charging circuit) to a final value of 0. Current ceases to flow when the capacitor has been fully discharged.

[See also:

http://www.scientia.org/cadonline/Physics/circuits/branch.ASP

http://www.scientia.org/cadonline/Physics/circuits/loop.ASP

http://www.scientia.org/cadonline/Physics/electrostatics/fields.ASP

http://www.scientia.org/cadonline/Physics/electrostatics/potential.ASP

http://www.scientia.org/cadonline/Physics/electrostatics/dipole.ASP

http://www.scientia.org/cadonline/Physics/electromagnet/fields.ASP

http://www.scientia.org/cadonline/Physics/electromagnet/biot.ASP

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Kirchoff's Laws and their application to alternating current (AC) circuits

Alternating currents or AC currents regularly change their direction of flow. The current and voltage obey equations that involve the sine function and that are derived through the use of calculus:

The term I max refers to the maximum amplitude of the sine wave.

Since sine waves are symmetrical, calculating the average current or voltage over one complete cycle yields an answer of 0. Since this quantity is meaningless, when considering the current of an AC circuit, a quantity known the root-mean-square (rms) current is used. This quantity is calculated to be

A similar quantity is used for voltage:





[Source: http://www.scientia.org/cadonline/Physics/capacitors/ac.asp]

Jan. 13, 2004

Greetings Gary:

I hope that some of the e-mail addresses on this old list are still valid. A retired radio man in Oregon recently asked me about Tesla's proposed system for wireless transmission of power. As you know, there is no easy answer to this question because there is so little clear information about what Tesla was doing in this regard. The following is my reply. I am passing it along to you because I thought it might be of general interest. Perhaps someone would forward it to Margaret Cheney.

I have not attached the material referred to, but I think you can follow the arguments without it. Most of the diagrams referred to are in my article about Tesla in the February and May 1999 issues of the Old Timer's Bulletin (OTB), published by the Antique Wireless Association. I hope that no one will take offence at some of my criticism of other people's interpretations of Tesla's wireless work, and I will not take offence at criticism of my views. . . .

. . . Since the mathematics would be very difficult, I believe that the best approach would be a numerical computer analysis, tracing the signal from the transmitter terminal and ground to the opposite end of the Earth, and done from a few Hertz to about a megahertz. Since a good mathematical model of the ionosphere and upper layers of the earth or ocean would be required, the same analysis could be done for conventional LF and VLF radio transmitters for comparison.

. . . My own rough analysis above leads me to believe that the Tesla system would be hopelessly ineffective for wireless transmission of power at the ultra-low Schumann resonance frequencies. If my numbers are correct, I cannot imagine what Tesla was thinking of. Tesla was no fool, but he may have been wrong about harnessing whole Earth resonance, if in fact that was what he planned to do.

. . . I believe that radio waves and Tesla earth currents would diminish with distance from their respective transmitters at roughly similar rates.

Cheers, Henry