Rotational speed
 

Roy Lewallen wrote:
Now if we could just get a certain individual to either stay on the
rotor or the stator and not keep jumping back and forth without telling
anyone or even realizing it himself. . .

I apologize for any confusion I may have created. All of my
phasors are referenced to the feedpoint current at zero
degrees, which is what EZNEC does.

If the feedpoint forward current is at zero degrees, the
forward current 45 degrees away will lag by 45 deg.
The reflected current 45 degrees away will lead by 45 deg.
The forward current 90 degrees away will lag by 90 deg.
The reflected current 90 degrees away will lead by 90 deg.
Thus the forward current and reflected current phasors
are rotating compared to the feedpoint reference.

The standing wave current phase, referenced to the feedpoint
phase, changes hardly at all. The standing wave current
phase is essentially the same all up and down the dipole.
The standing wave current phase is essentially the same at
the bottom and top of a loading coil. The standing wave
current phase is essentially unrelated to the position
on the antenna or loading coil. Standing wave current
cannot be used to determine the phase shift through
a loading coil.
--
73, Cecil http://www.w5dxp.com

Rotational speed
 

Roy Lewallen wrote in
:

with a rotational speed of omega * t radians/sec. The reason the
time-dependent rotational term

Should that be ...of omega radians/sec..., omega*t is the phase
displacement, omega is the phase velocity?

You're right. Thank you for the correction. My apology for the error.

And to correct myself, I really should have said angular displacement and
angular velocity respectively.

Owen

Analyzing Stub Matching with Reflection Coefficients
 

Cecil Moore wrote:

Gene Fuller wrote:

I heard a rumor that the FCC does not like people to inject class-C
type pulses directly into an antenna from the output of an amateur
transmitter.

Perhaps that rumor is just an urban legend, however, and non-linear
outputs are welcome.


The subject is modeling a class-C source, Gene,
not filtering a class-C source. We all know how
to filter a class-C source. Do you have a model
for a class-C source?

Well, we used to have one waaay back in Non-linear Transistor Design.
Done with harmonics and relatively simple math as I remember. Gave
remarkably accurate answers only using the fundamental plus 2 or 3 of
them. The course was mostly about tank circuits, doublers, triplers,
PLLs, etc. though, since the non-linear stuff was so easy once learned.

Of course it wasn't really a model of a class-C source, since it
actually did anything you could think of. So I guess it wouldn't qualify.

Sorry I mentioned the concept.

tom
K0TAR

Rotational speed
 

Keith Dysart wrote in news:1177719266.182305.327520
@l77g2000hsb.googlegroups.com:

On Apr 27, 7:36 pm, K7ITM wrote:
Grrrr. I'll try to
remember to check the couple of books I have that would talk about
phasors to see if I'm misrepresenting them, but I'm pretty sure they
are equally explicit in defining a phasor as a representation of ONLY
the phase and magnitude of the sinusoidal signal, and NOT as a vector
that rotates synchronously with the sinewave.

My recollection is of being introduced to phasors with the study of
electric machines which have real rotating magnetic fields. By
jumping onto the rotor and rotating with those magnetic fields,
solutions became trivial by allowing vector arithmetic on the now
stationary phasors.

Isn't hopping onto the rotor (assuming synchronous speed) to make your
observations called moving from the time domain to the frequency domain,
and all the mathematical shortcuts are only valid if all quantities share
the same angular velocity (or frequency), implying sinusoidal waveform.

I guess a departure from the strict phasor environment is for example
when we consider a noise vector rotating about the end of a carrier
phasor in exploring FM detector S/N vs C/N.

Owen

Analyzing Stub Matching with Reflection Coefficients
 

Tom Ring wrote:
Well, we used to have one waaay back in Non-linear Transistor Design.

Yes, I remember one from college but would have trouble
locating it 50 years later. :-)
--
73, Cecil http://www.w5dxp.com

Rotational speed
 

Owen Duffy wrote:
Isn't hopping onto the rotor (assuming synchronous speed) to make your
observations called moving from the time domain to the frequency domain,
and all the mathematical shortcuts are only valid if all quantities share
the same angular velocity (or frequency), implying sinusoidal waveform.

Ever wonder which direction, clockwise or counter-clockwise,
a standing-wave phasor is rotating?
--
73, Cecil http://www.w5dxp.com

Rotational speed
 

On Apr 27, 4:01 pm, Roy Lewallen wrote:
K7ITM wrote:

OK, noted, but your definition doesn't match what I was taught and
what is in the Wikipedia definition athttp://en.wikipedia.org/wiki/Phasor_(electronics).
What I was taught, and what I see at that URL, is that the PHASOR is
ONLY the representation of phase and amplitude--that is, ONLY the
A*exp(j*phi). To me, what you guys are calling a phasor is just a
rotating vector describing the whole signal. To me, the value of
using a phasor representation is that it takes time out of the
picture. See alsohttp://people.clarkson.edu/~svoboda/eta/phasors/Phasor10.html,
which defines the phasor very clearly as NOT being a function of time
(assuming things are in steady-state). But in my online search, I
also find other sites that, although they don't bother to actually
define the phasor, show it as a rotating vector. Grrrr. I'll try to
remember to check the couple of books I have that would talk about
phasors to see if I'm misrepresenting them, but I'm pretty sure they
are equally explicit in defining a phasor as a representation of ONLY
the phase and magnitude of the sinusoidal signal, and NOT as a vector
that rotates synchronously with the sinewave.

Tom,

I'm sure a lot of people forget the derivation of a phasor after using
it for a while, just as they do so many other things.

Again, a phasor is a complex representation of a real sinusoidal
function and, as such, definitely has a time varying component. That the
component isn't written doesn't mean it's not there. By all means, check
your texts. I'm sure that any decent circuit analysis text has a
serviceable development of the subject.

I always cringe when I see wikipedia quoted as a reference -- I was
referred to an entry regarding transmission lines some time ago, and it
contained some pretty major misconceptions. That leads me to mistrust it
when looking up a topic which I don't have a good grasp of. I don't have
a full understanding of the process by which it's written, but it seems
that all participants in this newsgroup are equally qualified to create
or modify a wikipedia entry. How could that result in a reliable reference?

Roy Lewallen, W7EL


Hi Roy,

Well, I did not forget the derivation. In Balabanian, "Fundamentals
of Circuit Theory," (a book I have but didn't actually study from) he
uses "sinor" instead of "phasor" but says they are the same, then in a
convoluted way gets around to saying that it's just the phase and
magnitude, and not the real(exp(jwt)) part. Smith, "Circuits,
Devices, and Systems," (most likely the book from which I learned
about phasors) is much clearer about it. Under "Phasor
Representation" in my edition,

"If an instantaneous voltage is described by a sinusoidal function of
time such as
v(t) = V cos (wt + theta)
then v(t) can be interpreted as the "real part of" a complex function
or
v(t) = Re {V exp[j*(wt + theta)]} = Re
{[V*exp(j*theta)]*[exp(j*wt)]} (eqn 3-18)
In the second form of eqn 3-18, the complex function in braces is
separated into two parts; the first is a complex constant, the second
is a function of tiem which implies rotation in the complex plane.
The FIRST PART we DEFINE [Tom's emphasis...] as the phasor (bold) V (/
bold), where
(bold) V (/bold) = V*exp(j*theta)
....
The phasor V is called a "transform" of the voltage v(t); it is
obtained by transforming a function fo time into a complex constant
which retains the essential information. ... "

OK, so your definition is different from mine. So far, I've found two
actual definitions of the phasor on-line, and both agree with my books
and my own useage. But if it's common useage to consider a phasor to
be a rotating vector, I'll defer to that at least in this discussion.
So far, though, I haven't found a reason to give up my definition of a
phasor. ;-)

Cheers,
Tom

Rotational speed
 

Owen Duffy wrote:

Isn't hopping onto the rotor (assuming synchronous speed) to make your
observations called moving from the time domain to the frequency domain,
and all the mathematical shortcuts are only valid if all quantities share
the same angular velocity (or frequency), implying sinusoidal waveform.

I guess a departure from the strict phasor environment is for example
when we consider a noise vector rotating about the end of a carrier
phasor in exploring FM detector S/N vs C/N.

That's why it's essential to not forget the implied exp(j * omega * t)
term -- all waveforms in an analysis must include it, and it must be the
same omega for all. In addition to inherently non-sinusoidal waveforms,
waveforms resulting from any nonlinear operation, such as frequency
modulation or multiplying or squaring waveforms, can't be analyzed in
that environment.

Roy Lewallen, W7EL

Rotational speed
 

K7ITM wrote:

OK, so your definition is different from mine. So far, I've found two
actual definitions of the phasor on-line, and both agree with my books
and my own useage. But if it's common useage to consider a phasor to
be a rotating vector, I'll defer to that at least in this discussion.
So far, though, I haven't found a reason to give up my definition of a
phasor. ;-)

Cheers,
Tom

I find it's convenient to think of a phasor as rotating with respect to
some other frequency, or stationary when you want to show the phase
relation at some specific frequency in a circuit with complex impedances.

For example, if you are discussing the phase relations in AM modulation,
you can set the carrier as a vector pointing to the right, and the upper
and lower sidebands rotating in opposite directions with their centers on
the end of the carrier vector.

The sidebands each have one half the amplitude of the carrier, so when they
are aligned in the same direction as the carrier, the resulting vector is
twice the amplitude, or length. When they oppose the carrier, the result is
zero amplitude.

So a phasor can be stationary or rotating depending on its relation to
something else in the discussion.

Regards,

Mike Monett

Rotational speed
 

On Apr 27, 9:15 pm, Owen Duffy wrote:
Keith Dysart wrote in news:1177719266.182305.327520
@l77g2000hsb.googlegroups.com:
My recollection is of being introduced to phasors with the study of
electric machines which have real rotating magnetic fields. By
jumping onto the rotor and rotating with those magnetic fields,
solutions became trivial by allowing vector arithmetic on the now
stationary phasors.

Isn't hopping onto the rotor (assuming synchronous speed) to make your
observations called moving from the time domain to the frequency domain,

I am not sure it is that; more like rotating the frame of reference to
stabilize the view (or a stroboscope perhaps?). The time domain is
now captured in the notation on the diagram that says it is all
happening
at 60 Hz, for example.

and all the mathematical shortcuts are only valid if all quantities share
the same angular velocity (or frequency), implying sinusoidal waveform.

But I agree with this. If everything is not rotating with the same
velocity
(and not just frequency), then it is difficult to find a useful frame
of reference
to rotate.

Which suggests that if there are two directions of rotation, phasors
don't help much with the solution.

I guess a departure from the strict phasor environment is for example
when we consider a noise vector rotating about the end of a carrier
phasor in exploring FM detector S/N vs C/N.

....Keith

Rotational speed
 

On Apr 27, 9:22 pm, Cecil Moore wrote:
Owen Duffy wrote:
Isn't hopping onto the rotor (assuming synchronous speed) to make your
observations called moving from the time domain to the frequency domain,
and all the mathematical shortcuts are only valid if all quantities share
the same angular velocity (or frequency), implying sinusoidal waveform.

Ever wonder which direction, clockwise or counter-clockwise,
a standing-wave phasor is rotating?

Clockwise, of course, by convention. Always look at the end of the
machine that lets you draw your phasor diagram clockwise.

This way, when a first phasor is clockwise from a second, the first
phasor occurs first when you convert back to time.

....Keith

Rotational speed
 

Mike Monett wrote:
So a phasor can be stationary or rotating depending on its relation to
something else in the discussion.

This is the way I have been assuming that everyone was
thinking. I'm amazed at all the different concepts.
--
73, Cecil http://www.w5dxp.com

Rotational speed
 

Keith Dysart wrote:
Which suggests that if there are two directions of rotation, phasors
don't help much with the solution.

By conventional definition, coherent phasors traveling
in opposite directions are rotating in different
directions, one clockwise and one counter-clockwise.

Adding a forward wave and a reflected wave of equal
amplitude results in:

E = Eot[sin(kx+wt) + sin(kx-wt)]

By convention, the forward +wt wave rotates counter-
clockwise as the angle increases in the + direction.

By convention, the reflected -wt wave rotates clockwise
as the angle increases in the - direction.

The standing wave equation becomes:

E(x,t) = 2*Eot*sin(kx)*cos(wt)

Which direction is the standing-wave phasor rotating?
--
73, Cecil http://www.w5dxp.com

Rotational speed
 

Keith Dysart wrote:
On Apr 27, 9:22 pm, Cecil Moore wrote:
Owen Duffy wrote:
Isn't hopping onto the rotor (assuming synchronous speed) to make your
observations called moving from the time domain to the frequency domain,
and all the mathematical shortcuts are only valid if all quantities share
the same angular velocity (or frequency), implying sinusoidal waveform.
Ever wonder which direction, clockwise or counter-clockwise,
a standing-wave phasor is rotating?

Clockwise, of course, by convention. Always look at the end of the
machine that lets you draw your phasor diagram clockwise.

The equation for a standing wave,

E(x,t) = 2*Eot*sin(kx)*cos(wt)

would have an identical value if it were written,

E(x,t) = 2*Eot*sin(kx)*cos(-wt)

Thus, a standing wave phasor can be considered to be
rotating either clockwise or counter-clockwise.
--
73, Cecil http://www.w5dxp.com

Rotational speed
 

On Apr 27, 10:25 pm, Cecil Moore wrote:
Keith Dysart wrote:
Which suggests that if there are two directions of rotation, phasors
don't help much with the solution.

By conventional definition, coherent phasors traveling
in opposite directions are rotating in different
directions, one clockwise and one counter-clockwise.

It would, I think, be more precise to say that the vectors are
rotating. When you change your point of view by rotating
the frame of reference along with the vectors, those vectors
become phasors which do not rotate. Although a little
looseness in the language easily leads to saying that
they do.

Adding a forward wave and a reflected wave of equal
amplitude results in:

E = Eot[sin(kx+wt) + sin(kx-wt)]

By convention, the forward +wt wave rotates counter-
clockwise as the angle increases in the + direction.

I agree. I should have said counter-clockwise in my other
post. Once you jump on the rotor to rotate counter-
clockwise with the vectors, the rest of the world (e.g.
the stator) appears to be going clockwise around you.

By convention, the reflected -wt wave rotates clockwise
as the angle increases in the - direction.

The standing wave equation becomes:

E(x,t) = 2*Eot*sin(kx)*cos(wt)

Which direction is the standing-wave phasor rotating?

Which I will try to answer in a response to your next post.

....Keith

Rotational speed
 

On Apr 27, 10:32 pm, Cecil Moore wrote:
Keith Dysart wrote:
On Apr 27, 9:22 pm, Cecil Moore wrote:
Owen Duffy wrote:
Isn't hopping onto the rotor (assuming synchronous speed) to make your
observations called moving from the time domain to the frequency domain,
and all the mathematical shortcuts are only valid if all quantities share
the same angular velocity (or frequency), implying sinusoidal waveform.
Ever wonder which direction, clockwise or counter-clockwise,
a standing-wave phasor is rotating?

Clockwise, of course, by convention. Always look at the end of the
machine that lets you draw your phasor diagram clockwise.

The equation for a standing wave,

E(x,t) = 2*Eot*sin(kx)*cos(wt)

would have an identical value if it were written,

E(x,t) = 2*Eot*sin(kx)*cos(-wt)

Thus, a standing wave phasor can be considered to be
rotating either clockwise or counter-clockwise.

I suggest that the solution to this ambiguity is to do the
same analysis for the current, which should be found to
be 90 degrees shifted from the voltage. The real current
is either leading or lagging the voltage. Rotate the frame
of reference in the direction that will cause a lagging
current to appear counter-clockwise from the voltage
and a leading current to appear clockwise from the
voltage.

This is all convention, of course. You can rotate the
frame of reference in either direction, you just need
to remember which direction on the graph represents
earlier time and which represents later.

Physically, it is just a question of which end of the
rotor you climb on to.

....Keith

Rotational speed
 

Keith Dysart wrote:
I suggest that the solution to this ambiguity is to do the
same analysis for the current, which should be found to
be 90 degrees shifted from the voltage. The real current
is either leading or lagging the voltage. Rotate the frame
of reference in the direction that will cause a lagging
current to appear counter-clockwise from the voltage
and a leading current to appear clockwise from the
voltage.

This just illustrates how artificial standing waves are.
For 1/4WL the standing-wave current leads the standing-
wave voltage by 90 degrees then suddenly undergoes a step
function to lag the standing-wave voltage by 90 degrees for
the next 1/4WL.

In any case, the point is whether standing-wave current can
be used to measure the phase shift through a loading coil.
EZNEC indicates that it cannot. Kraus indicates that it cannot.
Yet the people who did exactly that continue to report the
results as valid.
--
73, Cecil http://www.w5dxp.com

Rotational speed
 

On Apr 27, 6:39 pm, K7ITM wrote:
On Apr 27, 4:01 pm, Roy Lewallen wrote:



K7ITM wrote:

OK, noted, but your definition doesn't match what I was taught and
what is in the Wikipedia definition athttp://en.wikipedia.org/wiki/Phasor_(electronics).
What I was taught, and what I see at that URL, is that the PHASOR is
ONLY the representation of phase and amplitude--that is, ONLY the
A*exp(j*phi). To me, what you guys are calling a phasor is just a
rotating vector describing the whole signal. To me, the value of
using a phasor representation is that it takes time out of the
picture. See alsohttp://people.clarkson.edu/~svoboda/eta/phasors/Phasor10.html,
which defines the phasor very clearly as NOT being a function of time
(assuming things are in steady-state). But in my online search, I
also find other sites that, although they don't bother to actually
define the phasor, show it as a rotating vector. Grrrr. I'll try to
remember to check the couple of books I have that would talk about
phasors to see if I'm misrepresenting them, but I'm pretty sure they
are equally explicit in defining a phasor as a representation of ONLY
the phase and magnitude of the sinusoidal signal, and NOT as a vector
that rotates synchronously with the sinewave.

Tom,

I'm sure a lot of people forget the derivation of a phasor after using
it for a while, just as they do so many other things.

Again, a phasor is a complex representation of a real sinusoidal
function and, as such, definitely has a time varying component. That the
component isn't written doesn't mean it's not there. By all means, check
your texts. I'm sure that any decent circuit analysis text has a
serviceable development of the subject.

I always cringe when I see wikipedia quoted as a reference -- I was
referred to an entry regarding transmission lines some time ago, and it
contained some pretty major misconceptions. That leads me to mistrust it
when looking up a topic which I don't have a good grasp of. I don't have
a full understanding of the process by which it's written, but it seems
that all participants in this newsgroup are equally qualified to create
or modify a wikipedia entry. How could that result in a reliable reference?

Roy Lewallen, W7EL

Hi Roy,

Well, I did not forget the derivation. In Balabanian, "Fundamentals
of Circuit Theory," (a book I have but didn't actually study from) he
uses "sinor" instead of "phasor" but says they are the same, then in a
convoluted way gets around to saying that it's just the phase and
magnitude, and not the real(exp(jwt)) part. Smith, "Circuits,
Devices, and Systems," (most likely the book from which I learned
about phasors) is much clearer about it. Under "Phasor
Representation" in my edition,

"If an instantaneous voltage is described by a sinusoidal function of
time such as
v(t) = V cos (wt + theta)
then v(t) can be interpreted as the "real part of" a complex function
or
v(t) = Re {V exp[j*(wt + theta)]} = Re
{[V*exp(j*theta)]*[exp(j*wt)]} (eqn 3-18)
In the second form of eqn 3-18, the complex function in braces is
separated into two parts; the first is a complex constant, the second
is a function of tiem which implies rotation in the complex plane.
The FIRST PART we DEFINE [Tom's emphasis...] as the phasor (bold) V (/
bold), where
(bold) V (/bold) = V*exp(j*theta)
...
The phasor V is called a "transform" of the voltage v(t); it is
obtained by transforming a function fo time into a complex constant
which retains the essential information. ... "

OK, so your definition is different from mine. So far, I've found two
actual definitions of the phasor on-line, and both agree with my books
and my own useage. But if it's common useage to consider a phasor to
be a rotating vector, I'll defer to that at least in this discussion.
So far, though, I haven't found a reason to give up my definition of a
phasor. ;-)

Cheers,
Tom

More on this:

First, I agree with Mike's usage; if your phase reference is at one
frequency and you're looking at a signal at a different frequency with
respect to your reference, the phasor representing that different
frequency will rotate at a rate equal to the difference in the
frequencies: counterclockwise if the second frequency is higher, I
suppose, since the second frequency's phase gets further and further
ahead of the reference as time goes on.

Second, I did a google search for "phasor definition" and investigated
a whole bunch of sites. Some didn't have anything worth noting. I
made notes of 18 sites. Nine of them had strict mathematical
definitions. Every one of the mathematical definitions agreed that a
phasor contains only amplitude, and phase relative to a reference, and
has the exp(wt) part stripped out. Some had a full development of the
concept, and some only stated the end result, but in the result they
all agreed. In the nine narrative definitions/descriptions, five were
clear that a phasor contains only phase and amplitued and not time
information--not a rotating vector with respect to time (unless it's
representing a second frequency, presumably). Two of the narratives
specifically said that a phasor is a time-rotating vector. The others
were at best ambiguous, or simply didn't say.

To me, the whole idea of using phasors is to remove the time-varying
quantity from discussion, so you can concentrate on phase and
magnitude. As I showed in my first posting in this "subthread,"
phasors (as phase and magnitude only) very quickly lead you to an
accurate description of what happens with forward and reflected waves
on a transmission line, with respect to the amplitude and phase of the
net signal at any point along the line. The phasor representation
clearly shows that with waves of the same frequency of nearly equal
amplitude in each direction, you get relatively long stretches along
the line where the phase changes only slightly, and then a region
where it changes very quickly. That's not something I can easily see
in just thinking about the waves as time-varying quantites, but as
phasors, the result is immediately obvious to me. There are plenty of
other similar examples.

I'm very curious now to see exactly what Pearson & Maler and Van
Valkenburg say in their texts. Are they clear with a mathematical
definition, or do they end up just using words that can be interpreted
in different ways? So far, I have investigated eleven references that
define a phasor mathematically (the nine mentioned here plus the two
college texts mentioned before), and all agree that it doesn't contain
the exp(wt) component: in a linear system at steady-state excited by
a single frequency, a phasor representing a quantity at a single point
in space does not rotate.

I suppose I get a little carried away on things like this, but to me
it's important that we're communicating with words for which we share
a single definition, not words that mean distinctly different things
to different people.

Cheers,
Tom

Rotational speed
 

K7ITM wrote:
To me, the whole idea of using phasors is to remove the time-varying
quantity from discussion, so you can concentrate on phase and
magnitude.

Yes, that was what I was doing. I think that is what EZNEC
does. I think that is what Kraus does. It seems to be the
key in determining what phase shift occurs through a 75m
loading coil.

Incidentally, one of the best treatments of this subject,
IMO, is in "Optics", by Hecht.

I suppose I get a little carried away on things like this, but to me
it's important that we're communicating with words for which we share
a single definition, not words that mean distinctly different things
to different people.

Apparently, someone needs to get carried away in order to
get this problem resolved. A measured zero phase shift
through a loading coil using a current that doesn't change
phase is meaningless and misleading.
--
73, Cecil http://www.w5dxp.com

Rotational speed
 

On Apr 28, 8:54 am, Cecil Moore wrote:
This just illustrates how artificial standing waves are.

You have hit the nail on the head here.

In another post you provided two expressions for the spatial
and temporal distribution of voltage on the line...

A) E(x,t) = Eot[sin(kx+wt) + sin(kx-wt)]
B) E(x,t) = 2*Eot*sin(kx)*cos(wt)

There are an infinite number. Three immediately come to mind...

C) E(x,t) = expressed as an exponental
D) E(x,t) = expressed as a differential equation
E) expression A) can be re-expressed as an infinite
sum keeping track of all the individual reflections.

All of these accurately yield the correct E(x,t) and there are
similar expressions which correctly yield I(x,t). In the same
sense that B) (called by you the standing wave expression) is
artificial, they are all equally artificial. And yet they each
have their place for solving problems since they all, in the end,
yield the correct E(x,t), the only thing that actually exists.

For reasons hard to fathom, you have latched on to A) as
being THE TRUTH, though it really lacks any features to
distinguish it from the rest. D) is arguably a much better
choice for truth since it will handle signals other than
sinusoidal.

As said before, you would find it valuable to let go of A) as
THE TRUTH, since it would permit you to solve real world
problems that you currently refuse to solve because you
believe the technique for solution conflicts with A) as
TRUTH.

....Keith

Rotational speed
 

Keith Dysart wrote:
On Apr 28, 8:54 am, Cecil Moore wrote:
A) E(x,t) = Eot[sin(kx+wt) + sin(kx-wt)]
B) E(x,t) = 2*Eot*sin(kx)*cos(wt)

In the same
sense that B) (called by you the standing wave expression) is
artificial, they are all equally artificial.

A) is easy to understand. The amplitude is where it needs
to be and the phase is where it needs to be to be properly
comprehended.

B) is what has everyone confused. The phase information
readily apparent in A) is embedded in the amplitude in
equation B). For a lot of people, comprehension has
disappeared.
--
73, Cecil http://www.w5dxp.com

Rotational speed
 

On Apr 28, 11:01 am, Cecil Moore wrote:
It seems to be the
key in determining what phase shift occurs through a 75m
loading coil.

Cecil, don't even THINK of dragging that stinky old thing out again.
You're reminding me how incredibly rude you were to me one of the
previous times you beat your head against loading coils. What happens
with them is crystal clear to me and not in need of any further
discussion.

:-(

Tom

Rotational speed
 

K7ITM wrote:
Cecil, don't even THINK of dragging that stinky old thing out again.
You're reminding me how incredibly rude you were to me one of the
previous times you beat your head against loading coils. What happens
with them is crystal clear to me and not in need of any further
discussion.

I remember being rude to another Tom, but I don't remember
being rude to you. I don't even remember your position.

Would you mind summarizing your crystal clear position on
how many degrees a 75m bugcatcher coil occupies in a resonant
mobile antenna?
--
73, Cecil http://www.w5dxp.com

Rotational speed
 

K7ITM wrote:
On Apr 28, 11:01 am, Cecil Moore wrote:
It seems to be the
key in determining what phase shift occurs through a 75m
loading coil.

Cecil, don't even THINK of dragging that stinky old thing out again.
You're reminding me how incredibly rude you were to me one of the
previous times you beat your head against loading coils. What happens
with them is crystal clear to me and not in need of any further
discussion.

:-(

Tom



Cecil is trolling for an argument again. Ignore him.
73,
Tom Donaly, KA6RUH

Rotational speed
 

Tom Donaly wrote:
Cecil is trolling for an argument again. Ignore him.

Actually, I am trolling to reopen a technical discussion
that was not resolved in the past. What is your aversion
to a technical discussion?
--
73, Cecil http://www.w5dxp.com

Rotational speed
 

Cecil Moore wrote:
Tom Donaly wrote:
Cecil is trolling for an argument again. Ignore him.

Actually, I am trolling to reopen a technical discussion
that was not resolved in the past. What is your aversion
to a technical discussion?

Nice try, Cecil.
73,
Tom Donaly, KA6RUH

Rotational speed
 

K7ITM wrote:
. . .
I'm very curious now to see exactly what Pearson & Maler and Van
Valkenburg say in their texts. Are they clear with a mathematical
definition, or do they end up just using words that can be interpreted
in different ways? . . .

Sorry, I've been swamped, but will post some quotes soon.

Roy Lewallen, W7EL

Rotational speed
 

On Apr 28, 8:40 pm, Cecil Moore wrote:
K7ITM wrote:
Cecil, don't even THINK of dragging that stinky old thing out again.
You're reminding me how incredibly rude you were to me one of the
previous times you beat your head against loading coils. What happens
with them is crystal clear to me and not in need of any further
discussion.

I remember being rude to another Tom, but I don't remember
being rude to you. I don't even remember your position.

Would you mind summarizing your crystal clear position on
how many degrees a 75m bugcatcher coil occupies in a resonant
mobile antenna?
--
73, Cecil http://www.w5dxp.com

Yes, I would mind. It's in the archives of the newsgroup if you care
to look.

Tom

Rotational speed
 

K7ITM wrote:
Yes, I would mind. It's in the archives of the newsgroup if you care
to look.

Millions of postings are in the archives. Would you please give
a subject line and date? If it was in 2003, everyone was wrong
back then.
--
73, Cecil http://www.w5dxp.com

Rotational speed
 

On Apr 29, 2:18 pm, Roy Lewallen wrote:
K7ITM wrote:
. . .
I'm very curious now to see exactly what Pearson & Maler and Van
Valkenburg say in their texts. Are they clear with a mathematical
definition, or do they end up just using words that can be interpreted
in different ways? . . .

Sorry, I've been swamped, but will post some quotes soon.

Roy Lewallen, W7EL


More from my research (which is probably at an end at this point):

Bell, "Fundamentals of Electric Circuits," calls a phasor a rotating
vector, period.

IEEE Standard Dictionary of Electrical and Electronic Terms has
entries for both non-rotating and rotating definintions.

Christiansen, "Electronic Engineers' Handbook," defines a phasor
clearly as a non-rotating quantity.

This has been educational. Clearly there are people in both camps.
I'm obviously in the non-rotating camp, and it seems to be one with a
high population. I'll be careful to ask when someone writes of
phasors and their definition is not clear from the context, at least
if the distinction between the two definitions matters in that case.

Cheers,
Tom

Rotational speed
 

K7ITM wrote:
This has been educational. Clearly there are people in both camps.
I'm obviously in the non-rotating camp, and it seems to be one with a
high population.

I thought the non-rotating camp was the only one. Because
of that, I need to apologize to Roy, W7EL, who is apparently
in the rotating camp when he said that standing-wave phasors
have a rotational speed the same as the traveling wave. Since
he doesn't read my postings, would you please reply to this
one so he will see it? TNX
--
73, Cecil http://www.w5dxp.com

Rotational speed
 

K7ITM wrote:
More from my research (which is probably at an end at this point):

Bell, "Fundamentals of Electric Circuits," calls a phasor a rotating
vector, period.

IEEE Standard Dictionary of Electrical and Electronic Terms has
entries for both non-rotating and rotating definintions.

Christiansen, "Electronic Engineers' Handbook," defines a phasor
clearly as a non-rotating quantity.

This has been educational. Clearly there are people in both camps.
I'm obviously in the non-rotating camp, and it seems to be one with a
high population. I'll be careful to ask when someone writes of
phasors and their definition is not clear from the context, at least
if the distinction between the two definitions matters in that case.

I still haven't had the time to post the quotes. But I did look over Van
Valkenburg carefully, and he very clearly describes the quantity
including exp(jwt) as a phasor, and a page or two later describes the
term without the time-varying term as a phasor. So he uses both
definitions -- but I can't find anywhere that he actually defines
exactly what a phasor is. I got that text because it's one of the most
widely used circuits texts. Pearson and Maler, I have left over from
college -- I took classes from both of them, and we know how that works.

I'm happy to call a phasor a rotating vector or, better yet, a
description of a rotating vector (the description consisting of phase
and amplitude). This way, I can have my rotation without needing to have
the phasor itself rotate. The important thing, as I see it, is to
realize that:

-- It results from a substitution of a complex time-varying quantity for
a real time-varying quantity;
-- The time-varying part of the complex quantity is not used in
calculations because it cancels; and
-- The fact that the complex quantity is time-varying is essential to
the method and solution.

but I guess it's up to the individual to decide whether he wants to
declare that time-varying part (exp(jwt)) to be part of the "phasor" or
something just attached to it.

Thanks, this has been stimulating and educational. I'll still try to get
those quotes down.

Roy Lewallen, W7EL

Rotational speed
 

Roy Lewallen wrote:
but I guess it's up to the individual to decide whether he wants to
declare that time-varying part (exp(jwt)) to be part of the "phasor" or
something just attached to it.

Here's a quote from "Optics", by Hecht:
"Because both phasors rotate together at a rate w,
we can simply freeze them at t=0 and not worry
about their time dependence, which makes them a
lot easier to draw."

This is what EZNEC does - freeze the feedpoint
current at t=0 to 1 amp at zero degrees. The
current reported by EZNEC at loads is then
referenced to that feedpoint current phasor.

The fact remains that the phase of the total
current in a standing wave antenna, like a 1/2WL
dipole or a loaded mobile antenna, cannot be used
to measure the phase shift in a wire, much less
be used to measure the phase shift in a loading
coil.
--
73, Cecil http://www.w5dxp.com

MFJ-259
 

MFJ-259
Dropped from the roof LCD display broken (all black}. Dos any one know
what the description of the lcd is, or manufacturer P/n ? I like to by
from a supplier not MFJ there replacement parts are very expensive .
ie. meter $60 found one on line $3.00 MFJ #50-247-3
TNX JB K1JZP

Rotational speed
 

Cecil, W5DXP wrote:
"Here`s a quote from "Optics" by Hecht:
"Because bith phasors rotate together at a rate w, we can simply freeze
them at t=0 and not worry about their time dependence, which makes them
a lot easier to draw."

Raymond B. Yarbrough writes in the 5th ed. of "Electrical Engineering
Reference Manual" on page 1-1:
"A complex number can also be represented as a two-dimensional vector
in a complex plane. Thus, the complex number can be written in polar or
phasor form as

a+jb=c on an angle phi

c=square root of a squared + b squared

phi = arctan (b/a) "

On page 3-15 Yarborugh wrote:
In electric circuits involving sinusoids it is more convenient to deal
with RMS values of voltage and current rather than with peak values, and
with angles in degrees rather than with radians (Angles in the
exponential form must be in radians for mathematical calculations.)

Thus, an alternative representation, which is called the effective value
phasor notation has evolved."

Best regards, Richard Harrison, KB5WZI

Rotational speed
 

Charles M. Close in "The Analysis of Linear Circuits" has this
footnote in a section called Representing Sinusoidal Function of Time:

"Although directed lines are commonly called vectors, this terminology
is avoided in this application. In field theory, quantities that have
an orientation in three-dimensional space and that are sinusoidal
functions of time are encountered. The term "vector" then refers to
the spacial orientation, and the term "rotating phasor" to the
exponential terms [Fe^jwt and its complex conjugate]. Since both
phasors and vectors are complex quantities, phasors are added and
subtracted in the same way as vectors."

According to the text, since the two complex functions of t in
exponential form can be graphically represented as directed lines, and
since each is the conjugate of the other, they are called
counter-rotating phasors. They each make w/2pi revolutions per second
and have an angular frequency of w radians per second.

ac6xg


Richard Harrison wrote:
Cecil, W5DXP wrote:
"Here`s a quote from "Optics" by Hecht:
"Because bith phasors rotate together at a rate w, we can simply freeze
them at t=0 and not worry about their time dependence, which makes them
a lot easier to draw."

Raymond B. Yarbrough writes in the 5th ed. of "Electrical Engineering
Reference Manual" on page 1-1:
"A complex number can also be represented as a two-dimensional vector
in a complex plane. Thus, the complex number can be written in polar or
phasor form as

a+jb=c on an angle phi

c=square root of a squared + b squared

phi = arctan (b/a) "

On page 3-15 Yarborugh wrote:
In electric circuits involving sinusoids it is more convenient to deal
with RMS values of voltage and current rather than with peak values, and
with angles in degrees rather than with radians (Angles in the
exponential form must be in radians for mathematical calculations.)

Thus, an alternative representation, which is called the effective value
phasor notation has evolved."

Best regards, Richard Harrison, KB5WZI

Rotational speed
 

Jim Kelley wrote:
According to the text, since the two complex functions of t in
exponential form can be graphically represented as directed lines, and
since each is the conjugate of the other, they are called
counter-rotating phasors.

Is it talking about forward and reflected currents?
If the forward and reflected currents are of equal
magnitudes, which direction does the standing-wave
current phasor rotate?
--
73, Cecil http://www.w5dxp.com

MFJ-259
 

JB MacDonald wrote:

MFJ-259
Dropped from the roof LCD display broken (all black}. Dos any one know
what the description of the lcd is, or manufacturer P/n ? I like to by
from a supplier not MFJ there replacement parts are very expensive .
ie. meter $60 found one on line $3.00 MFJ #50-247-3
TNX JB K1JZP
many years ago I broke the display on my 259. I located the display
supplier but they would not sell me one. They claimed they had a
exclusive contract with MFJ. I sent the unit in and MFJ repaired the
display. I don't remember what it cost then.
Check with MFJ as to repair costs.

Dave WD9BDZ

Rotational speed
 

Cecil Moore wrote:
Jim Kelley wrote:

According to the text, since the two complex functions of t in
exponential form can be graphically represented as directed lines, and
since each is the conjugate of the other, they are called
counter-rotating phasors.


Is it talking about forward and reflected currents?

It's talking about electromagnetic wave functions, so it applies to
actual electromagnetic waves.

If the forward and reflected currents are of equal
magnitudes, which direction does the standing-wave
current phasor rotate?

A clue might have been in one of the parts you deleted said that
phasors add just like vectors. A standing 'wave' is not as much a
wave as it is an interference pattern. It is an amplitude as a
function of position, not as a function of time. The phasor for a
standing wave would then rotate as a function of position; the
direction of rotation would depend on the direction you're moving
along the transmission line.

73, Jim AC6XG

Rotational speed
 

Jim Kelley wrote:
The phasor for a standing wave would then
rotate as a function of position; the direction of rotation would depend
on the direction you're moving along the transmission line.

What if I'm not moving - just sitting still at a point?
--
73, Cecil http://www.w5dxp.com