Gene Fuller wrote:

Cecil,
Until you try to understand the difference between current in a
conductor and power radiated into space, this is a hopeless debate.

Isn't there a direct correlation between current in a radiator and
power radiated into space? Assuming the conservation of energy
principle holds, power radiated into space reduces the current
in a radiator (since the ratio of the forward voltage in a radiator
and the forward current in a radiator is proportional to the power
available). Sorry to say, Gene, the current drops in proportion to
the drop in the voltage in a fixed Z0 environment. If a terminated
traveling-wave antenna were 100 wavelengths long, it's current at
the termination would be a small percentage of the source current.

Hint: ExH = Poynting Vector power and the E/H ratio is constant.

Until you give up on the possibility of a point inductance
existing in reality, this is a hopeless debate. I can't believe
you are defending an indefensible model of reality, so I can only
conclude that you are defending the irrational premise of a friend.
You and I are obviously on the same side of physics and you are to be
commended for being a good enough friend to that un-named someone
to set aside your knowledge of physics and side with his/her
irrational premises, arguments, and conclusions. The reason that
I don't have any such friends is that I wouldn't accept that kind
of support if I was wrong. But I do understand it is human nature
to respond in such a manner.

The ARRL Antenna Book and various other publications give the
characteristic impedance of a horizontal single-wire TRANSMISSION
LINE over ground as:

Z0 = 138*log(4h/d) where 'h' is the height and 'd' is the diameter

Doesn't a "horizontal single-wire transmission line over ground"
sound a lot like a dipole made out of #16 wire 24 feet above ground
having a Z0 of 600 ohms?

If you ignore that question, I will assume your position on this
subject has everything to do with friendship and nothing to do
with physics. Actually, like Richard C. and I, I don't think
you and I have any argument about physics.
--
73, Cecil http://www.qsl.net/w5dxp


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Cecil,

Were you there when the Germans bombed Pearl Harbor?

(That was a great movie. Are you related to the late John Belushi?)


My views are completely based on physics principles. I have endless
argument with your views on physics.

I have never met nor corresponded with Tom D., Tom R. or Roy L. I just
happen to agree with their public writings.

73,
Gene
W4SZ

Cecil Moore wrote:


If you ignore that question, I will assume your position on this
subject has everything to do with friendship and nothing to do
with physics. Actually, like Richard C. and I, I don't think
you and I have any argument about physics.

Gene Fuller wrote:
Are you related to the late John Belushi?)

According to DNA analysis, most Americans of European decent are
amazingly closely related - Nth cousins. Bush is supposed to be
a cousin of Kerry's. Besides London, the city with the highest
population named "Moore" is Houston, TX, 90 miles South of me.

My views are completely based on physics principles. I have endless
argument with your views on physics.

Then why are ad hominem attacks all you have to offer? Why not share
some of you physics knowledge with us? I've got Balanis, Kraus, Johnson,
and Hecht on my side. Who's on your side?

I have never met nor corresponded with Tom D., Tom R. or Roy L. I just
happen to agree with their public writings.

I suspect Roy L., being a reasonable fellow, is in the process of changing
his mind given the latest EZNEC helical evidence. How about you?

Please pick one item of physics with which you disagree with me and let's
discuss it in a gentlemanly fashion. There's some pretty savvy people on
this newsgroup who agree with me. Perhaps, the argument is only a semantics
problem, like the definition of "drop" and "flow". It's really hard to see
how an E-field can drop but not flow and an H-field can flow but not drop.

Pick one simple topic upon which you think you and I disagree. So far,
you have posted nothing except ad hominem attacks. That's not a good
way to impress people and win technical arguments. I think you are a
better person than that.

Here's a topic if you can't think of one. How can a one foot long section
of transmission line exhibit a phase shift if a one foot long coil doesn't?
--
73, Cecil http://www.qsl.net/w5dxp
"The current and voltage distributions on open-ended wire antennas are
similar to the standing wave patterns on open-ended transmission lines ...
Standing wave antennas, such as the dipole, can be analyzed as traveling
wave antennas with waves propagating in opposite directions (forward and
backward) and represented by traveling wave currents If and Ib ..."
_Antenna_Theory_, Balanis, Second Edition, Chapter 10, page 488 & 489


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Cecil,

I was going to drop this discussion, but I will respond to your request
to share physics knowledge.

1) I will repeat. E-fields, H-fields, voltages, and currents are all
related through some very profound equations. However, shout THEY ARE
NOT INTERCHANGEABLE. /shout

This is not just a matter of semantics. These entities have different
physical meanings, different units, and different dimensionalities.

2) I offered a physics-based explanation for your proposed "current
drop" in the 440 MHz RG-58 example a few days ago. Did you not read that
message before responding to it?

3) A one foot long section of wire and a one foot long section of coil
exhibit similar phase shifts, according to both the theory and the
reported data. What is not correct is the assertion that the coil
exhibits a phase shift consistent with, for example, 20 feet of wire
used to make the coil. The notion that a coil replaces some sizable
portion of the total phase shift in an antenna has been shown to be
incorrect. Experiments reported by Roy and Tom R. convincingly
demonstrate the phase shift behavior of coils.

73,
Gene
W4SZ


Cecil Moore wrote:

[snip]

Please pick one item of physics with which you disagree with me and let's
discuss it in a gentlemanly fashion. There's some pretty savvy people on
this newsgroup who agree with me. Perhaps, the argument is only a semantics
problem, like the definition of "drop" and "flow". It's really hard to see
how an E-field can drop but not flow and an H-field can flow but not drop.

Pick one simple topic upon which you think you and I disagree. So far,
you have posted nothing except ad hominem attacks. That's not a good
way to impress people and win technical arguments. I think you are a
better person than that.

Here's a topic if you can't think of one. How can a one foot long section
of transmission line exhibit a phase shift if a one foot long coil doesn't?

Gene Fuller wrote:
I was going to drop this discussion, but I will respond to your request
to share physics knowledge.

Thanks, Gene, Please be patient with me.

1) I will repeat. E-fields, H-fields, voltages, and currents are all
related through some very profound equations. However, shout THEY ARE
NOT INTERCHANGEABLE. /shout

Is the H-field around a wire proportional to the RF current in the wire?
Is the E-field around a wire proportional to the RF voltage between the
wires? Is the ratio of E-field to H-field fixed by Z0? Do I^2*R losses
affect the E-field and H-field by equal amounts?

This is not just a matter of semantics. These entities have different
physical meanings, different units, and different dimensionalities.

Of course that's true. However, they are not unrelated.

2) I offered a physics-based explanation for your proposed "current
drop" in the 440 MHz RG-58 example a few days ago. Did you not read that
message before responding to it?

Yes, and I have been thinking about an example that would better illustrate
what I was asking. A 1000 wavelength dipole located in outer space would
have less current at the ends than at the source. Since there is no other
path for current, what is the explanation for the decrease in the current
at the ends?

3) What is not correct is the assertion that the coil
exhibits a phase shift consistent with, for example, 20 feet of wire
used to make the coil.

Because nobody has made that assertion since the original eHam article, it
appears to be a straw man. The coil occupies whatever number of degrees
that it occupies and it does NOT occupy zero degrees.

For instance, using a particular EZNEC segment model of a coil, the
current at the bottom is 1.0 amp and the current at the top is 0.5
amp. Assuming the cosine distribution of standing-wave current is
accurate, the coil occupies about 60 degrees. The whip would occupy
about 30 degrees, the rest of the 1/4WL.

Nobody has attempted to explain how one can obtain 90 degrees of a
1/4WL antenna on 4 MHz using a ten foot (15 degree) whip. That is
one hell of a velocity factor. If the bottom-loading coil really
occupies zero degrees, then the ten foot whip would be forced to
occupy 90 degrees. That is so impossible as to be laughable.

The notion that a coil replaces some sizable
portion of the total phase shift in an antenna has been shown to be
incorrect. Experiments reported by Roy and Tom R. convincingly
demonstrate the phase shift behavior of coils.

The total current undergoes virtually no phase shift since it is a
standing wave. That's in the textbooks and nobody is arguing that
point so it's just another straw man.

It's the forward current and reflected current that is undergoing a
phase shift through the coil just like they do on a wire standing-
wave antenna. Nobody has measured those two current components so
the jury is still out on that subject. There is no argument about
the phase of the total current that Roy and Tom measured. Please,
there are enough arguments already without having to introduce
straw men.

If you will look at my phasor diagrams of forward and reflected
currents at:

http://www.qsl.net/w5dxp/current.htm

you will see that the phase of the total current is exactly the same
in both cases. That's the phase that Roy measured. Since it is a
standing wave current, the phase of the standing-wave current is almost
constant. It is the magnitude of the standing-wave current that
changes and it changes as a cosine function of electrical length
in degrees. The coil has an electrical length in degrees. That's
what causes the current to be different at the bottom and at the
top in a 1/4WL antenna. Assuming the phase shift from the feedpoint
current to the tip of the antenna is 90 degrees, if an accurate
measurement of the current at the top and bottom of a bottom-loaded
antenna coil is made, the number of degrees occupied by the coil can
be calculated from

arccos(Itop/Ibottom)

just as it can be calculated between two points on a wire. This
assumes that Ibottom is an Imax point on the standing wave.
--
73, Cecil http://www.qsl.net/w5dxp


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Cecil,

1) Only the total current matters. I have never found a detailed
treatment of antennas that was based on anything other than the total
current (or total current density) at each point on the antenna. Have you?

Current components may be useful for discovering the total current or
for handwaving explanations, but they have no further role in antenna
analysis.

2) Where did this 90 degree phase shift requirement come from? There is
virtually no phase shift in the current of a half-wave dipole (or
quarter-wave monopole) from feedpoint to tip. I am looking at figure 9.6
on page 370 in Kraus "Antennas" (2nd Ed.), and it shows perhaps a few
degrees phase variation over the entire length of the dipole antenna.
This figure is located in the chapter on the Moment Method for
calculating cylindrical antennas, in case you do not have the second
edition.

I suspect you may be confusing the argument (AKA, the phase) of the
cosine function presumed to describe the behavior of the current
amplitude. However, current amplitude and current phase are not at all
the same thing.

Have you been seduced by your math models?

73,
Gene
W4SZ


Cecil Moore wrote:

[snip]


Because nobody has made that assertion since the original eHam article, it
appears to be a straw man. The coil occupies whatever number of degrees
that it occupies and it does NOT occupy zero degrees.

For instance, using a particular EZNEC segment model of a coil, the
current at the bottom is 1.0 amp and the current at the top is 0.5
amp. Assuming the cosine distribution of standing-wave current is
accurate, the coil occupies about 60 degrees. The whip would occupy
about 30 degrees, the rest of the 1/4WL.

Nobody has attempted to explain how one can obtain 90 degrees of a
1/4WL antenna on 4 MHz using a ten foot (15 degree) whip. That is
one hell of a velocity factor. If the bottom-loading coil really
occupies zero degrees, then the ten foot whip would be forced to
occupy 90 degrees. That is so impossible as to be laughable.

The notion that a coil replaces some sizable portion of the total
phase shift in an antenna has been shown to be incorrect. Experiments
reported by Roy and Tom R. convincingly demonstrate the phase shift
behavior of coils.


The total current undergoes virtually no phase shift since it is a
standing wave. That's in the textbooks and nobody is arguing that
point so it's just another straw man.

It's the forward current and reflected current that is undergoing a
phase shift through the coil just like they do on a wire standing-
wave antenna. Nobody has measured those two current components so
the jury is still out on that subject. There is no argument about
the phase of the total current that Roy and Tom measured. Please,
there are enough arguments already without having to introduce
straw men.

If you will look at my phasor diagrams of forward and reflected
currents at:

http://www.qsl.net/w5dxp/current.htm

you will see that the phase of the total current is exactly the same
in both cases. That's the phase that Roy measured. Since it is a
standing wave current, the phase of the standing-wave current is almost
constant. It is the magnitude of the standing-wave current that
changes and it changes as a cosine function of electrical length
in degrees. The coil has an electrical length in degrees. That's
what causes the current to be different at the bottom and at the
top in a 1/4WL antenna. Assuming the phase shift from the feedpoint
current to the tip of the antenna is 90 degrees, if an accurate
measurement of the current at the top and bottom of a bottom-loaded
antenna coil is made, the number of degrees occupied by the coil can
be calculated from

arccos(Itop/Ibottom)

just as it can be calculated between two points on a wire. This
assumes that Ibottom is an Imax point on the standing wave.

Gene Fuller wrote:
1) Only the total current matters. I have never found a detailed
treatment of antennas that was based on anything other than the total
current (or total current density) at each point on the antenna. Have you?

Check out my tag line, Gene. Balanis says we can use the component
currents If and Ib to analyze a standing-wave antenna. Kraus says
essentially the same thing when he says: "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 an antenna." This was in regards to the
"Fields of a thin linear antenna with a uniform traveling wave."

Just because there is no "detailed treatment" doesn't mean that it
should be forbidden to discuss. We are out on the edge of what has been
detailed (so far) so don't be afraid to think outside of the box. The
opposite phase shift between If and Ib is the cause of the decrease in
coil current in a typical mobile antenna. It happens even if there is
zero loss in the coil and zero radiation from the coil. It also
happens in a lossless transmission line. There is a decrease in standing
wave current on each side of a current maximum point even when the
transmission line is lossless. The same thing applies to a lossless
coil with dimensions larger than a point.

Current components may be useful for discovering the total current or
for handwaving explanations, but they have no further role in antenna
analysis.

Check my tag line again, Gene. They are absolutely useful for transmission
line analysis and are therefore useful for standing-wave antenna analysis.

2) Where did this 90 degree phase shift requirement come from? There is
virtually no phase shift in the current of a half-wave dipole (or
quarter-wave monopole) from feedpoint to tip.

Yes, you are talking about the standing-wave current which is the
superposition of the forward and reflected currents. A 1/4WL wire
is 90 degrees of a traveling-wave antenna. The forward current rotates
by 90 degrees and the reflected current rotates by 90 degrees.

I am looking at figure 9.6
on page 370 in Kraus "Antennas" (2nd Ed.), and it shows perhaps a few
degrees phase variation over the entire length of the dipole antenna.

Yes, that is true for the superposed forward and reflected currents and
is shown to be true by my phasor diagrams on my web page. The forward
current is a traveling wave. The reflected current is a traveling wave.
I'm sure you are familiar with the change in phase undergone by traveling
waves in perfectly matched systems. Apply that knowledge to the separate
forward and reflected current traveling waves and you will understand
the magnitude variation in If+Ib caused by their respective phase shifts
in the opposite direction even if their magnitudes remain constant.

I suspect you may be confusing the argument (AKA, the phase) of the
cosine function presumed to describe the behavior of the current
amplitude. However, current amplitude and current phase are not at all
the same thing.

Nope, I fully agree that the superposed net current has almost zero
phase shift because it is a *standing wave*. Traveling waves, OTOH,
experience phase shifts when traveling along a wire. The forward
current and reflected current on a standing-wave antenna are
*traveling waves*.

This is an onion-type problem, Gene. Please peal back the net current
layer and look at the component currents underneath even if you feel
presently that it will be a waste of time.

Incidentally, I bounced most of this stuff off of Dr. Balanis when
I was working with him on a joint Intel/ASU project. He agreed so
far (1995) and my extensions since 1995 are logical. If you will
take it step-by-step, I think you will agree. If you find any error
at all on my part, you will, no doubt, call my attention to it and
I will learn something.
--
73, Cecil http://www.qsl.net/w5dxp
"The current and voltage distributions on open-ended wire antennas are
similar to the standing wave patterns on open-ended transmission lines ...
Standing wave antennas, such as the dipole, can be analyzed as traveling
wave antennas with waves propagating in opposite directions (forward and
backward) and represented by traveling wave currents If and Ib ..."
_Antenna_Theory_, Balanis, Second Edition, Chapter 10, page 488 & 489


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