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Jim Kelley wrote:
Cecil Moore wrote: The energy in the canceled waves is "redistributed" in the opposite direction in the transmission line as constructive interference. But as I said, there is no energy where there are no waves, so the sentence makes no sense. There is no "energy in canceled waves". There existed energy in the two waves before they were canceled. Their ExH Poynting vectors had equal magnitudes and direction. Their phases were opposite and they canceled. Their energy components cannot be canceled or annihilated so the energy is redistributed in the only other direction available. Exactly what is it about the FSU web page that you do not understand? Concerning the reflected wave cancellation process at a non- reflective 1/4WL thin-film coating: http://micro.magnet.fsu.edu/primer/j...ons/index.html "... when two waves of equal amplitude and wavelength that are 180-degrees ... out of phase with each other meet, they are not actually annihilated, ... All of the photon energy present in these waves must somehow be recovered or redistributed in a new direction, according to the law of energy conservation ... Instead, upon meeting, the photons are redistributed to regions that permit constructive interference, so the effect should be considered as a redistribution of light waves and photon energy rather than the spontaneous construction or destruction of light." From Ramo & Whinnery, Page 440: Waveguides - Elimination of Reflections from Dielectric Slabs. "For slabs of any thickness, reflections may be eliminated by canceling the reflected wave from one slab by that from another placed a proper distance from it." Before wave cancellation, the two waves contained energy. After cancellation, they ceased to exist in their original direction of travel. Energy cannot cease to exist so it has to go somewhere. This is not rocket science. You have tied yourself into a Gordian Knot. If there is no canceled wave energy to redistribute, then there were no reflected waves to begin with and the anti-reflective coating was completely unnecessary. Peel it off and see what happens. -- 73, Cecil http://www.w5dxp.com |
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