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Cecil Moore wrote:
Gene Fuller wrote: The graph is complete nonsense. There is no rotation of the fields when they undergo reflection. Any ordinary text on E&M or optics will show you the equations and the correct sketches. Good grief, Gene. There is a 360 degree rotation in the fields every wavelength. The direction of rotation is associated with the direction of travel of the wave and is displayed by EZNEC when the current phase option is turned on. All you have to do to see the rotation of the traveling wave is to download http://www.w5dxp.com/rhombicT.EZ Those simplified sketches are making you simple-minded. Assuming you are a member of the IEEE, look up this paper: "Rotation in electromagnetic field equations". Or Google "Rotation and the Electromagnetic Field". "Optics", by Hecht, is one of your ordinary texts. That is where the material for that graph comes from. The IEEE Dictionary says: "E and H are the electric and magnetic field vectors in phasor notation". If that graph is nonsense to you, it is your fault, not mine. Hecht says "Optics", 4th edition, page 289, about standing waves: "The composite disturbance is then: E = Eo[sin(kx+wt) + sin(kx-wt)] Applying the identity: sin A + sin B = 2 sin 1/2(A+B)*cos 1/2(A-B) yields: E(x,t) = 2*Eo*sin(kx)*cos(wt)" "This is the equation for a STANDING or STATIONARY WAVE, as opposed to a traveling wave. Its profile does not move through space; it is clearly not of the form Func(x +/- vt)." "... a phasor rotating counterclockwise at a rate omega is equivalent to a wave traveling to the left (decreasing x), and similarly, one rotating clockwise corresponds to a wave traveling to the right (increasing x)." Hecht uses phasors to represent EM waves all through his book. He explains the standing wave E-field based on the two traveling waves, E1-field and E2-field, thusly: "The resultant phasor is E1 + E2 = E ... Keeping the two [traveling wave] phasors tip-to-tail and having E1 rotate counterclockwise as E2 rotates (at the same rate) clockwise, generates E [total] as a function of 't'." [Standing wave phase] "doesn't rotate at all, and the resultant wave it represents doesn't progress through space - its a standing wave." Traveling wave phase rotates. Standing wave phase doesn't. Speaking of "... net transfer of energy, for the pure standing wave there is none." The forward wave and reflected wave E-field and H-field vectors are represented by phasors just as indicated in the IEEE Dictionary. One is rotating clockwise and the other is rotating counterclockwise. The Poynting vector for a pure standing wave is equal to zero just as illustrated in my graph at: http://www.w5dxp.com/EHSuper.JPG Given those boundary conditions and solving for the angle between the standing wave E-field and H-field yields 0 or 180 degrees. Are you really more interested in presenting false information and saving face than you are in valid technical facts? Cecil, This is truly sad. I thought you had finally begun to understand this stuff, but you have regressed back into the same old nonsense. You are still totally confusing phasors with field vectors. They are utterly, totally, and absolutely unrelated. Get help. Call me what you like. Bye. 73, Gene W4SZ |
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