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Gene Fuller wrote:
Sorry, I missed the comments that Kraus made about the phase of a standing wave. Quoting: "Figure 14-2 Relative current amplitude AND PHASE along a center-fed 1/2WL cylindrical antenna." Emphasis mine so you can't miss it this time. I thought you were knowledgable enough to convert Kraus's independent variable of wavelength to degrees in his graph on page 464 of the 3rd edition of "Antennas For All Applications". Allow me to assist you in that task. The 'X' axis is "Distance from center of antenna in WL" X in X in wavelength degrees 0.00 0 0.05 18 0.10 36 0.15 54 0.20 72 0.25 90 Hope that helps you to understand Kraus's graph better. Using the degree column, the standing wave current, Itot, on that graph equals cos(X). The standing wave current also equals Ifor*cos(-X) + Iref*cos(X) where 'X' is the phase angle of the forward traveling current wave and the rearward traveling current wave. A phasor diagram at 0.02WL = 72 degrees would look something like this: / Iref / / +----- Itot = Ifor*cos(-X) + Iref*cos(X) \ \ \ Ifor Incidentally, from the above phasor diagram, it is easy to see why the phase angle of the standing wave current is always zero (or 180 deg) since Ifor and Iref are rotating in opposite directions at the same phase velocity. -- 73, Cecil http://www.qsl.net/w5dxp |
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