Re: Physics of Wireless Transmission

["Tesla list" <tesla@xxxxxxxxxx>]

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

Langer,

After reading "Electric Waves" by J.J. Thomson I 
retract my assertion that the term "electric 
wave" is synonymous with "electromagnetic 
radiation.  On page 207, § 9. Waves in Wires, 
Thompson discusses apparatus for investigating 
"electric waves along wires."  (View the page at 
http://www.newscotland1398.net/radio40/encybrit1911v09p207.html 
.)  The term "electric wave" is actually 
synonymous with "electromagnetic wave."

Strictly speaking, all forms of electromagnetic 
radiation exist as an electromagnetic wave, but 
not all electromagnetic waves are electromagnetic 
radiation.  An example of EM wave propagation 
that is not electromagnetic radiation is the flow 
of electrical energy across a transmission line, such as coaxial cable.

Gary Peterson


----- Original Message ----- From: "Tesla list" <tesla@xxxxxxxxxx>
To: <tesla@xxxxxxxxxx>
Sent: Sunday, April 09, 2006 3:43 PM
Subject: Physics of Wireless Transmission


> Original poster: "Gary Peterson" <gary@xxxxxxxxxxxx>
>
> Langer,
>
> The physics of wireless transmission of 
> electrical energy by "radio wave," also known as 
> the "electric wave," aka "electromagnetic (EM) 
> radiation," aka "Hertzian radiations" is 
> described by Maxwell's Field Equations. These 
> terms refer to the emanation of a dipole radio 
> antenna.  An explanation of this dynamic 
> process, including a short movie, is available 
> online at http://www.colorado.edu/physics/2000/waves_particles/wpwaves6.html .
>
> Electromagnetic radiation carries energy and 
> momentum which may be imparted when it interacts 
> with matter.  Absorption takes place as a radio 
> wave passes from a dielectric medium into a 
> conducting medium, such as the earth, the 
> ionosphere or a radio wave receiving antenna, 
> resulting in a conversion of radiated energy back into electrical current..
>
> A term related to "electromagnetic radiation" is 
> "electromagnetic wave." This term is used to 
> broadly describe electrical energy propagated 
> through either free space or a material 
> medium.  Examples of free-space electromagnetic 
> wave propagation are radio waves, infrared 
> radiation, visible light, ultraviolet radiation, 
> X rays, and gamma rays; all of these are forms 
> of electromagnetic radiation.  An example of 
> electromagnetic wave propagation that is not in 
> the form of electromagnetic radiation is the 
> flow of electric and magnetic fields and their 
> associated electric current along and through an electrical conductor.
>
> There is an alternate to EM radiation for 
> wireless transmission of electrical energy.   As 
> Matt D. points out, "Two [Tesla] coils . . . can 
> couple capacitively."  The transmission of 
> electrical energy is in the form of an EM wave, 
> specifically an alternating current flowing 
> through the earth, along with its associated 
> electric and magnetic field energy, between the 
> ground terminal of the Tesla coil RF transmitter 
> and the ground terminal of the Tesla coil 
> receiving transformer.  In addition to current 
> flowing through the earth, current also flows 
> between the transmitter's elevated terminal and 
> the receiver's elevated terminal. This 
> transmission-reception system is called 
> "wireless" in that does not involve the 
> propagation of an electric current through a 
> wire as might be purchased from an electrical 
> wire manufacturer.  The energy flows throughout 
> the system as electric current and, in some 
> cases, displacement current as well.
>
> The physics of wireless transmission of 
> electrical energy by conduction is also 
> described by Maxwell's Field Equations, in 
> combination with the Navier-Stokes Equations of 
> Fluid Dynamics.  As Bob (R.A.) Jones points out, 
> "There are some fine details if . . . 
> capactively coupled is electromagnetic 
> propagation. . . ," that it's "terribly 
> complicated. . . ," and, "There are people that 
> insist . . . the method is . . . simply not 
> electromagnetic waves."  Of course the 
> Tesla-coil energy transmission method must 
> involve electromagnetic waves--there is no other 
> overarching mechanism available.
>
> Gary Peterson
>
>
> > Subject: physics of wireless transmission?
> >
> > Original poster: "Langer Giv'r" <transworldsnowboarding19@xxxxxxxxxxx>
> >
> > Hello, I am just curious on the physics of how electrical energy is
> > transmitted wirelessly.  Is it like the propagation of electromagnetic
> > radiation like radio transmission or is it not waves at all?  Are there
> > any sites out there that would be helpful towards this inquiry?  It would
> > be great to figure out how tesla coils do what they do, thanks for the
> > help!