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Roy Lewallen wrote:
So where do you draw the required surface over which to integrate the Poynting vector and thus obtain the "reflected power"? As you know, a one-dimensional transmission line is a lot easier to work with than the 3D space involved with radiation from antennas. In fact, all we need for a transmission line Poynting vector is a plane. Since the field area of the coax is constant and known, we can treat it as a constant normalized value. It allows us to come up with a simplified version of what you posted. Quoting from, "Fields and Waves in Communications Electronics", by Ramo, Whinnery, and Van Duzer: "... we are often most interested in the ratio of power in the reflected wave to that in the incident wave, and this ratio is given by ... Pz-/Pz+ = |rho|^2" where Pz- is the reflected power Poynting vector, Pz+ is the forward power Poynting vector, and rho is the reflection coefficient. Pretty simple stuff that I learned 45 years ago. Again from the same book: Pz+ = (E+)x(H+) and Pz- = -(E-)x(H-) -- 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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