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Szczepan Bialek wrote:
"W5DXP" napisal w wiadomosci ... On Wednesday, July 25, 2012 3:11:31 AM UTC-5, Szczepan Bialek wrote: So: enters in = radiates from;? To the extent that RF energy penetrates to a skin effect depth, the conductor is not perfect and dissipates some of the power. All real-world antennas dissipate some of the RF power in I^2*R (and possibly dielectric) losses. In an efficient antenna, most of the system energy is "lost" in space as coherent radiation. When the free electrons in a conductor are acting as a bucket brigade for the RF fields/waves/photons, they are essentially vibrating in place because of their very slow drift velocity. Those I^2*R losses in the wire are due to coherent RF photons that are absorbed by electrons and not re-emitted as coherent RF photons but are instead converted to heat energy, the price that Mother Nature requires be paid for all that vibration. In an antenna that is 90% efficient, 10% of the coherent RF energy is converted into non-coherent heat energy. That's the energy that Poynting was talking about. Pointing was writting in 1884. He described the DC current. His result is caused by the assumption that the Biot-Savart law is right. Is it? S* You are an ignorant, babbling, ineducable idiot who knows absolutely NOTHING about antennas or how they work. You don't even understand what an antenna is or the difference between an electric field, a magnetic field, and an electromagnetic field. Electrostatic and magnetostatic fields are created by DC. An antenna is a device that converts the AC electrical energy at it's teminals into electromagnetic energy which radiates from the antenna and also coverts the electromagnetic energy which antenna intercepts into AC electrical energy at it's terminals. That is ELECTROMAGNETIC energy, not magnetostatic nor electrostatic energy. From http://en.wikipedia.org/wiki/Biot%E2%80%93Savart_law "The Biot-Savart law is fundamental to magnetostatics, playing a similar role to Coulomb's law in electrostatics. When magnetostatics does not apply, the Biot-Savart law should be replaced by Jefimenko's equations." What that means, you babbling idiot, is that Jefimenko's equations apply to antennas, not the Biot-Savart law or Coulomb's law. Jefimenko's equations were first published in the 1960's so anything written before then is essentially irrelevant to a discussion of antennas. How many antennas have you built in your lifetime? Why do you refuse to answer the question? Is it because you have built zero antennas and you are trying to say all the people that have successfully built hundreds that they are all wrong and you don't want to admit you are an ignorant, inducable, idiot? Why can't you obtain and read a university level textbook on anything in any language? Is it because you are too stupid to be able to understand the material? |
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