Tranlated spanish document named TRANSMISOR VLF

page 1 out of 3,

TRANSMITTING VLF
Majorities:
The subject of the mathematical treatment of the reflections and amplifications in the ionosphere is a little complex to analyze traditional physical route of fields, for this reason, as the engineers are good to model, those complications are eliminated enough with a good model, the best model turns out to be one circuital and not of field equations, but before the following concepts of the physics of propagation of electromagnetic waves must consider.
Transmitting antenna: Generally series is a resonant circuit, with its resistance, Rd, inductance L and capacity C, as it is appraised in the Fig.l, this case since the frequency is very low for the physical lengths of wave, the antenna has a capacity actually, this capacity is very low what offers a very high impedance in transmission and a very low efficiency, similar or worse than the one of the antennas of the traditional transmitters in A.M., that is to say, the radiated power she is much more small that the power consumed by the transmitter, for that reason the ideal would be to eliminate this capacity to obtain the maximum possible power output.
This stray capacitance cannot be eliminated, but their effects can be eliminated applying a pulse of AT to that condenser, that generally can be modeled like an air dielectric condenser, because between the radiator of the antenna and the shield there is air and it is enough to overcome his dielectric strenght to cortocircuitar the condenser as if there was a switch in parallel or disruptor

(diagram here)

Fig.l. Model transmitting antenna
Radiation resistance: It is the resistance in series with the capacity of the antenna VLF and represents the transferred power or radiated to the space, for simple vertical antennas, whose physical length is inferior to % of wave, valid for the antennas VLF, its value in Ohms calculates by the formula:

(work out)

And its capacity in tip farads is:

(work out)

l is the length of the radiator in inches, /la frequency in Megahertz, K their height in feet, D the diameter of the radiator in inches.
Poityng vector: It indicates the intensity of radiation and direction of propagation of a travelling electromagnetic wave in means, his magnitude is in Watts by squared meter, useful to know the intensity the electrical or magnetic component certain distance of

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page 2,

transmitter and how the amplitude of the wave decays, because as a wave member state propagates, still by the free space, its intensity decays
For an isotropic radiator, that is that emit waves member state in all the directions, or spherical waves, from power of transmission P, applying the previous thing, obtains the following formula for the electrical field strenght (to a distance r of the transmitter:

(work out here)

Resistance of propagation: In fact it is an impedance, but it interests the resistiva component to us that she is the one that inflicts casualties majors and symbolizes the effect of the energy loss of wave member state as it propagates by the free space.


For the isotropic radiator, its value in Ohms according to (1) is:
(work out here)

Being [the distance to the transmitter.
Like the antenna that we would use is not isotropic, but directional, it is enough to multiply by a special correction constant, that is to say instead of to consider propagation spherical we can consider a cylindrical propagation for the parabolic one, or conic section for the directional dipole.
To this resistance a temporary retardation must also be added him, like the traditional lines of communication, and represent in this case, the time that the wave delays in crossing the distance between the terrestrial surface and the ionosphere during a reflection

Model of the ionosphere:
The equivalent circuit for this case of the ionosphere, is a resonant circuit parallel LC, that it has to the condenser loaded to a continuous potential, the condenser is the capacity between the ionosphere and the Earth or the spherical condenser associate, and the inductance the produced one by the electrical currents that circulate around the spherical layer of the ionosphere. This resonance is assumed in the fundamental one of 7,8 Hertz, since shown circuit LC oscillates only in the fundamental one, the linearities could not simulate the harmonicas

(diagram here)

Fig.2 Model Ionosphere
Somebody could say that here it lacked the resistance because it also must have it, losses, yes is certain, but, we must consider that the continuous source represents the energy of the loads that continuously are accumulated in the ionosphere originating of the Sun, reason why this system is being always red-supply, and the loss is not feasible.

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page 3,

Complete model of the transmitter:
The following model is the equivalent circuit of all the system, transmitter, antenna, ionosphere:

(diagram here)

Fig 3 complete Model of the transmitting VLF
The shown oscillating source or like AT OSC, corresponds to the oscillator of High voltage whose circuit is omitted here, but battery employee, because it depends on the type of antenna to use and his particular geometry, if dipole it is armored or parabolic, its frequency would have to be in the rank of 7,8 Hertz and adapted amplitude to unload the radiator of the antenna to Earth or shield of the antenna, would have to be order of the tens of Kilo Volt, Rg corresponds to the internal resistance of the oscillator and has to do with the power of the oscillator, that would have to be low, Ca is the stray capacitance of the antenna formed between the radiator and earth or shield, interrupting-disruptor SW, it models the unloading of the Ca condenser when the High voltage of the oscillator exceeds the tension of rupture of the system, this because the stray capacitance of antenna is a condenser, but of air dielectric that separates the radiator of the shield to Earth, value of a few Kilo Volt, this, because the dielectric strenght of the air in normal conditions is of 30 KV by centimeter of separation between radiator and earth; thus then when unloading Ca it is as if SW was closed, and all the power of the oscillator is transferred to the radiation resistance Rd, in the form of electromagnetic pulse of high power, but low energy, that travels through the propagation resistance, Rp, towards the ionosphere formed by the resonant block, the block formed by Rp is not a simple resistance, must include the effect of retardation and reflection, for that reason it is locked in to him like a block, a line of communication of equal temporary retardation while it delays the travelling wave in arriving at the layer of equal reflection to x/c, being x the trajectory of the wave, and c speed of the light. Thus then, by means of successive reflections the amplification of the signal in the transmitter can be appreciated and useful power can be obtained from down.
In fact the resistance of the generator, Rg and capacity C conform a self-sustained oscillation, even though the voltage of the generator is continuous.
By:      Mam 70 (CB, 123mail.cl, jarayam&Jatinmail. com

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thank you, Juan for coming back to do the english translation for us.I think I now have enough info to proceed.triffid

It is a good enough translation to get the idea about what they are talking about,had to include the pictures of the scientific workouts to get a better picture,took about 2 hours to do all that,useing software which would cost over ?500/978 usd .

Well enjoy,feel sorry for the guy who had to type, this software does it in seconds to translate.

I had a friend look at this material and he pretty much said that he doubts it can generate 5 kw as it is tiltled.He said maybe just under a kilowatt.He gave that much hope.

I am sorry for casting doubts on this device .I certainly dont want to belittle anyone's
efforts here.I want to build something bigger than a battery charger or crystal radio set.Also my friend may be in error .I might be in error.I only see one capacitor in the diagram.Right now I'm only working on one speed between work and family and that is SLOW.Triffid

I must admit I'm still a little confused here but now realize that the diagram here is not complete.
The pictures says what the diagram does not.There are 4 diodes in the picture and only two in the diagram.There might be a secondary coil in the picture but not in the diagram.The Notch filter can only be another capacitor..I can guess where the third diode goes but not the fourth,not yet.I'm still working on this.Triffid

I will look again,Thanks.Triffid

hello,again .While I have not made much progress here.I did find someone who had. (www.vlf.it).It is a website all about very low freqs(less than 22hz).It's all in english.triffid.