Cecil Moore wrote:
Tom Donaly wrote:
(P.S. Where did you learn about "dual Z0" stubs?)

While I was figuring out why Roy's "measurements"
were very accurate but virtually meaningless.

This is, of course, referring to Roy's "measurements"
of the "delay" through a 75m mobile loading coil as
being close to zero since there was "no measurable phase
shift" - as if the phase shift had anything to do with
the delay in a standing wave antenna. Hint: It doesn't!

Any person with a modicum of mathematics skill can
look at the following equation and know that there
is no phase shift relative to x in 1/4WL of wire or
coil.

Itot = Imax*cos(kx)*cos(wt)

Since Roy has known these details for more than
five years, I can only assume that he knows that
he is wrong but refuses to admit it - hoping that
his guru status will continue to promote his
old wives' tale.
--
73, Cecil, IEEE, OOTC, http://www.w5dxp.com

Cecil Moore wrote:

Any person with a modicum of mathematics skill can
look at the following equation and know that there
is no phase shift relative to x in 1/4WL of wire or
coil.

To the extent that 'a modicum of mathematics skill' is
like 'a little knowledge', I suppose anything is possible.

Itot = Imax*cos(kx)*cos(wt)

Noting the linear variables and constants in there, and the absence of
anything that would change abruptly at certain particular values of x,
what would the expression for a standing wave on a shortened coil loaded
90 degree monopole have to look like?

ac6xg

"To convert from units of current to units of mass simply multiply the
superposition trig identity by mass (and ignore the factor of 2): Mtot =
Mmax*cos(kx)*cos(wt). Try it with any units you like!"

Jim Kelley wrote:
Cecil Moore wrote:
Itot = Imax*cos(kx)*cos(wt)

Noting the linear variables and constants in there, and the absence of
anything that would change abruptly at certain particular values of x,
what would the expression for a standing wave on a shortened coil loaded
90 degree monopole have to look like?

Ideally, it would be of the form:

For x = 0 to top of coil,
Itot = k1*cos(k2*x)cos(wt)

For x = bottom of stinger to top of stinger,
Itot = k3*cos(k4*x)*cos(wt)

where k1-k4 are constants

Note: The above is a conceptual simplification as it
ignores the current "bulge" in a real-world loading
coil.

Note that at the coil/stinger junction:

Itot = k1*cos(k2*x)*cos(wt) = k3*cos(k4*x)*cos(wt)

- as required by the laws of physics. Remember, it is
always implied that we are considering only the real
part of the phasor. Thus a current phasor can undergo
an abrupt amplitude and phase shift without changing
the real value.

10*cos(0) = 14.14*cos(45) = 10

The above phasor has abruptly rotated its phase by
45 degrees and increased its amplitude by 41% with
no violation of the laws of physics.
--
73, Cecil, IEEE, OOTC, http://www.w5dxp.com

On Apr 29, 5:09*am, Cecil Moore wrote:
Jim Kelley wrote:
Cecil Moore wrote:
Itot = Imax*cos(kx)*cos(wt)

Noting the linear variables and constants in there, and the absence of
anything that would change abruptly at certain particular values of x,
what would the expression for a standing wave on a shortened coil loaded
90 degree monopole have to look like?

Ideally, it would be of the form:

For x = 0 to top of coil,
Itot = k1*cos(k2*x)cos(wt)

For x = bottom of stinger to top of stinger,
Itot = k3*cos(k4*x)*cos(wt)

where k1-k4 are constants

Note: The above is a conceptual simplification as it
ignores the current "bulge" in a real-world loading
coil.

It ingores almost everything about the antenna.

Note that at the coil/stinger junction:

Itot = k1*cos(k2*x)*cos(wt) = k3*cos(k4*x)*cos(wt)

Uh, what units did you say your constants k1-k4 had again?

- as required by the laws of physics.

Is that supposed to automatically add credibility to any remark which
preceeds it? Thusly, the nano-particles emitted by the framistat at
an impedance discontinuity carry only re-reflected energy - as
required by the laws of physics. It does sound impressive.

10*cos(0) = 14.14*cos(45) = 10

The above phasor has abruptly rotated its phase by
45 degrees and increased its amplitude by 41% with
no violation of the laws of physics.

Cecil -

Mathematics is NOT a toy.

:-)

ac6xg

"Jim Kelley" wrote in message
...
Is that supposed to automatically add credibility to any remark which
preceeds it? Thusly, the nano-particles emitted by the framistat at
an impedance discontinuity carry only re-reflected energy - as
required by the laws of physics. It does sound impressive.

It sounds like something art would say!

Jim Kelley wrote:
Mathematics is NOT a toy.

Sorry that it is beyond your comprehension level.
--
73, Cecil, IEEE, OOTC, http://www.w5dxp.com

Cecil Moore wrote:
Jim Kelley wrote:
Mathematics is NOT a toy.

Sorry that it is beyond your comprehension level.

So I take it you weren't able to answer the question, address the
issues, or resist posting insults.

ac6xg

Jim Kelley wrote:
So I take it you weren't able to answer the question, address the
issues, or resist posting insults.

I posted the math. You posted opinions devoid of
any technical content. Your assertions about
"nano-particles emitted by the framistat" do not
deserve a serious response.
--
73, Cecil, IEEE, OOTC, http://www.w5dxp.com

Jim Kelley wrote:
Cecil Moore wrote:
Note: The above is a conceptual simplification as it
ignores the current "bulge" in a real-world loading
coil.

It ingores almost everything about the antenna.

According to Kraus, the standing waves are the *primary*
effect associated with a standing-wave antenna. Everything
else is indeed a secondary effect. The standing wave current
is about 90% of the total steady-state current. Like a low-
loss transmission line, a loaded mobile antenna can be
analyzed by assuming that it is lossless.

"Antennas", by Kraus, 3rd edition, Standing Wave Antennas

Page 187: "A sinusoidal current distribution may be
regarded as the standing wave produced by two uniform
(unattenuated) traveling waves of equal amplitude moving
in opposite directions along the antenna."

Page 464: "It is generally assumed that the current
distribution of a thin-wire antenna is sinusoidal, and
that the phase is constant over a 1/2WL interval, ..."

Both of Kraus' statements assume a lossless antenna.

Note that at the coil/stinger junction:
Itot = k1*cos(k2*x)*cos(wt) = k3*cos(k4*x)*cos(wt)

Uh, what units did you say your constants k1-k4 had again?

k1 and k3 have the units of current and are the magnitude
of the two standing-wave current phasors on each side of
the coil/stinger junction.

k2 and k4 have the units of degrees/unit-length so when
they are multiplied by x, the result is degrees. Of course,
it could be radians/unit-length.
--
73, Cecil, IEEE, OOTC, http://www.w5dxp.com

Cecil Moore wrote:
Jim Kelley wrote:
It ignores almost everything about the antenna.

"Antennas", by Kraus, 3rd edition, Standing Wave Antennas

Kraus on the other hand ignores almost nothing about antennas. (for ref.
I'm looking at his 2nd edition.)

Uh, what units did you say your constants k1-k4 had again?

k1 and k3 have the units of current and are the magnitude
of the two standing-wave current phasors on each side of
the coil/stinger junction.

k2 and k4 have the units of degrees/unit-length so when
they are multiplied by x, the result is degrees. Of course,
it could be radians/unit-length.

So the constants in your equations for current on the segments of a coil
loaded monpole a maximum current, wave number, and frequency; and the
linear variables are time, and distance.

Of those things, only maximum current would have any dependence at all
on the nature of the antenna. How does one know what value Imax to
plug-in for each segment?

ac6xg