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Nic. Santean wrote:
I did the computations : the composition of those two "EM emissions" 90 degree out of phase (but having the same period) leads to a wave of exactly the same wavelength as the signal applied to the antenna. So, there is no contradiction in my scenario so far. Methinks the situation is a little more complicated than that. The E-field and H-field is in phase at the feedpoint of a resonant dipole. In the real world, they are never 90 degrees out of phase, but they get close to 90 degrees at the points midway between the feedpoint and the ends of the resonant dipole. The E-field and H- field are (almost) back in phase at the ends of the dipole. The ratio of net total voltage to net total current at points along a dipole can be thought of as a spiral on a Smith Chart. It is much like a transmission line where the spacing between wires is too large for the frequency of operation and therefore leaks radiation. -- 73, Cecil http://www.qsl.net/w5dxp -----= Posted via Newsfeeds.Com, Uncensored Usenet News =----- http://www.newsfeeds.com - The #1 Newsgroup Service in the World! -----== Over 80,000 Newsgroups - 16 Different Servers! =----- |
#12
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We are talking about half wavelength dipole antennas, right ?
Nic. Methinks the situation is a little more complicated than that. The E-field and H-field is in phase at the feedpoint of a resonant dipole. In the real world, they are never 90 degrees out of phase, but they get close to 90 degrees at the points midway between the feedpoint and the ends of the resonant dipole. The E-field and H- field are (almost) back in phase at the ends of the dipole. The ratio of net total voltage to net total current at points along a dipole can be thought of as a spiral on a Smith Chart. It is much like a transmission line where the spacing between wires is too large for the frequency of operation and therefore leaks radiation. |
#13
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Nic. Santean wrote:
We are talking about half wavelength dipole antennas, right ? Yes. A 1/2WL dipole can be thought of as a very leaky transmission line. It has standing waves that leak radiation into the Æther. :-) May I suggest trying to understand traveling-wave antennas before getting into standing-wave dipoles? Consider a terminated V-beam or terminated Rhombic to eliminate the confusion associated with reflected waves. But don't feel bad about confusion associated with reflected waves. Some of the r.r.a.a gurus don't understand reflected waves and the energy plus momentum involved in their very existence. So many sacred cows - so little time. :-) Methinks the situation is a little more complicated than that. The E-field and H-field is in phase at the feedpoint of a resonant dipole. In the real world, they are never 90 degrees out of phase, but they get close to 90 degrees at the points midway between the feedpoint and the ends of the resonant dipole. The E-field and H- field are (almost) back in phase at the ends of the dipole. The ratio of net total voltage to net total current at points along a dipole can be thought of as a spiral on a Smith Chart. It is much like a transmission line where the spacing between wires is too large for the frequency of operation and therefore leaks radiation. -- 73, Cecil http://www.qsl.net/w5dxp -----= Posted via Newsfeeds.Com, Uncensored Usenet News =----- http://www.newsfeeds.com - The #1 Newsgroup Service in the World! -----== Over 80,000 Newsgroups - 16 Different Servers! =----- |
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