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#11
April 9th 06, 09:47 AM
posted to rec.radio.amateur.antenna
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Current across the antenna loading coil - from scratch
John Popelish wrote:
Cecil Moore wrote: wrote: But what I really want to know is how Cecil can have current flowing both directions at the same instant of time in a single point of single conductor, Forward and reflected EM waves, of course. Would you like to deny the existence of the two waves in the following equation? I(x,t) = I1*cos(kx+wt) + I2*cos(kx-wt) = Io*cos(kx)*cos(wt) Those two expressions describe patterns of current over time and location that produce current in each direction half the time (except at nodes, where the current is zero). The amplitude of a current cycle is constant for the first one (traveling wave), but the phase differs at different locations (by the amount of kx). The amplitude of current cycle described by the second one (traveling wave) varies with location, and the phase has only two possibilities (one when cos(kx) is positive and 180 degrees different when cos(kx) is negative). But in both cases, current at any point reverses twice a cycle (cos(wt)) and charge goes nowhere over a cycle. I hope you guys realize that the stated equation is correct only when I1 = I2. Otherwise the solution is a sine or cosine function with a phase term. Roy Lewallen, W7EL |
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