Walter Maxwell wrote:
In a stub constructed of lossless material the only current that flows in the
stub is that required to bring it up to the steady statecondition.

In a practical stub with attenuation current flows into the stub continually,
but only that sufficient to compensate for the loss due to attenuation to retain
it's steady state condition.

All that is true for *NET* current, Walt. But a full magnitude of forward and
reflected current is flowing in and out of the mouth of the stub. All of the
reflections in a stub occur at the shorted end. What happens at the mouth of
the stub is superposition and interference, not reflection. The forward and
reflected voltages superpose (in phase) to a high net value and the forward
and reflected currents superpose (out of phase) to a low net value.

(|Vfwd|+|Vref|)/(|Ifwd|-|Iref|) = very high V/I ratio = very high impedance,
but that high impedance is an effect and not the cause of anything (except
arguments on r.r.a.a :-)

Inside the stub, Vfwd/Ifwd = Z0 and Vref/Iref = Z0

Anyone can prove this to himself. Install a wattmeter 1/8WL down into the 1/4WL
shorted stub. One will read high forward power and high reflected power. From
those powers, one can actually calculate the forward and reflected voltages
and currents at that halfway point within the stub given that halfway point
is equal to 45 degrees.
--
73, Cecil http://www.qsl.net/w5dxp



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