Thread: Vincent antenna
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Old December 4th 07, 09:35 PM posted to rec.radio.amateur.antenna
Cecil Moore[_2_] Cecil Moore[_2_] is offline
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First recorded activity by RadioBanter: Mar 2007
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Default Loading Coils; was : Vincent antenna

Jim Kelley wrote:
You have a habit of switching
references without noticing or making note of it. This makes some of
your comments a bit confused sounding, if not blatantly inaccurate.


Jim, it's all your fault for not being telepathic. :-)
I admit that my thought processes are somewhat chaotic
but remember, order often comes out of chaos. I've
experienced an epiphany or two in my time.

I also have a bad habit of declaring something invalid
when it is only irrelevant. It is the conclusions drawn
from irrelevant measurements that are invalid, not the
measurements themselves.

The convention that I try to use is the EZNEC convention.
Everything is referenced to the source signal. When I say
the phase of a standing wave is unchanging, I mean that it
has the same phase as the source signal at the feedpoint
and is the same phase as reported by EZNEC. I apologize for
not being clear about that.

With regard to your comment above, if the maximum amplitude and period
of a sinusoidal wave are both known, then given any instantaneous
amplitude and, knowing whether the slope is positive or negative, the
instantaneous phase can be readily determined.


Take I = K1*cos(x)*cos(wt), a standing-wave equation.
Let t be any fixed value. cos(x) is an amplitude value
and does NOT vary with time. Therefore, the phase of the
standing-wave signal is constant at any particular time
and does NOT depend upon position along the wire or coil.

Now take I = K2*cos(x+wt), a traveling-wave equation.
Let t be any fixed value. The length dimension 'x'
has an effect on phase, i.e. the phase of of the
signal indeed does depend upon BOTH position AND time.

Anyone who understands the math would not dare show
his ignorance by asserting that the delay through a
100T coil is 3 ns on 4 MHz or that the measured phase
shift through a loading coil is somehow proportional
to the delay through the coil in a standing-wave antenna.
--
73, Cecil http://www.w5dxp.com