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Old December 20th 07, 03:23 PM posted to rec.radio.amateur.antenna
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Default Standing-Wave Current vs Traveling-Wave Current

4nec2 wrote:
Roger wrote:

Congratulations on a clever use of zero resistance loads.


I am probably missing something, but why not just show the currents
and phase in the 'View Antenna' window ?


For current phase, EZNEC does not display the same
absolute phase as the "Load Dat" function reports.
That would appear to be a bug in the EZNEC GUI
software.

I'm glad you asked that question. Perhaps W7EL can tell
us why EZNEC does not display the same current phase as
it reports in the "Load Dat" function. EZNEC seems to
display the current amplitude correctly but it is unclear
exactly what EZNEC is displaying when the current phase
box is selected. That's why I used the "Load Dat" feature.

Here is a graphic using the "View Antenna" window for
the EZNEC files TravWave.EZ and StndWave.EZ.

http://www.w5dxp.com/eznec.jpg

Looking at TravWave.EZ with the current phase turned
off, the current displayed is indeed the amplitude of
the current up and down the wire which is essentially
a constant RMS magnitude.

But with the current phase turned on, the display does
not display the same phase reported by "Load Dat". It
displays a cosine function when the actual phase function
is a straight sloping line varying from 0 degrees at the
feedpoint to -90 degrees at the load resistor. What
EZNEC is actually displaying associated with phase
is unclear, confusing, and misleading.

StndWave.EZ has the same unclear display for phase.
The current amplitude is the correct cosine function
but the current phase is misleading. The "Loads Dat"
function says the phase varies from 0 degrees at the
feedpoint to -0.11 deg at the open end of the wire,
i.e. virtually no change at all in phase up and down
the wire. Yet EZNEC displays a cosine function for the
current phase the meaning of which is unclear.

To answer your question, EZNEC does not display phase
when the current phase box is selected. It is unclear
to me exactly what EZNEC is displaying when the current
phase box is selected.
--
73, Cecil http://www.w5dxp.com
 
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