Roy Lewallen wrote:
In a linear system like an antenna or transmission line, superposition
applies. ... We must get exactly the same result, ...
If Cecil's analysis shows, or his theory requires, that the result be
different when adding the responses to traveling current waves than it
is by calculating the response directly from the total current, then the
analysis or theory is wrong. Superposition requires that the two results
be identical.
Superposition does not require that all information be preserved
through the superposition process. Here's an example:
Two people are across the room from each other with a coax cable running
between them. They each have two identical PSK modems but only one coax.
When they use one modem pair, any information one sends is received 100%
by the other. When they use the other modem pair, any information one
sends is received 100% by the other. When they superpose the signals
over the single coax line, all phase information is lost. The superposition
results are the same but all phase information is lost in the process.
The rules of superposition do not apply to the phase information content.
The phase information is lost in the process of superposition.
In like manner, the rules of superposition do not apply to the ability
of a standing wave to detect phase shift. The phase information is
lost in the process of superposition. One cannot use standing wave
current phase to measure the electrical length of a wire or a coil.
A 75m wire dipole is known to be close to 90 degrees long from the
feedpoint to the tip. EZNEC says the current changes phase by 2.5
degrees. How can current change phase by only 2.5 degrees in an
antenna wire known to be 90 degrees long?
Since EZNEC's standing wave current cannot detect a phase shift in
90 degrees of wire, why should it detect a phase shift in a coil?
If standing wave current measurements cannot detect a phase shift
in 90 degrees of wire, why should anyone's measurements detect a
phase shift in a coil?
--
73, Cecil
http://www.qsl.net/w5dxp