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On Tue, 16 May 2006 05:54:59 GMT, Cecil Moore
wrote: Roy Lewallen wrote: It looks like Cecil is trying to use "phase" as a function of position, Referenced to the source current, the phase of the forward traveling wave current *IS* directly proportional to position along the dipole. Any competent engineer knows that. So is the phase of the rearward traveling wave current. That is obvious from the equations for those two currents. Those are simply facts of physics that you probably should try to comprehend instead of dismissing them. Inet = Io*cos(X)*cos(wt) = Ifor*cos(-X+wt) + Iref*cos(X-wt) Inet is the standing wave current. X is the distance in degrees from the feedpoint. If the source current is 1.0 amps at 0 degrees, e.g. from EZNEC, at t=0 Inet = Io*cos(X) = Ifor*cos(-X) + Iref*cos(X) As I pointed out some time ago, the envelope of a standing wave isn't in general sinusoidally shaped. Balanis says: "If the diameter of each wire is very small (d lamda) the ideal standing wave pattern of the current along the arms of the dipole is sinusoidal with a null at the end." Kraus says: "It is generally assumed that the current distribution of an infinitesimally thin antenna is sinusoidal,..." d lamda for an 80m dipole made out of #18 wire. I'm sorry to hear that you disagree with both Balanis and Kraus. Could you explain how to build one of those antennas that has infinite impedance at its ends? 73 Gary K4FMX |
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