Cecil Moore wrote:

For engineers, the direction of the arrow for the Power
Flow Vector in joules/sec is generally accepted to be the
same as the direction of the joules.

I am an engineer, Cecil. I just happen to work in the field of physics.
I could be wrong, but I don't think a Bird wattmeter measures or
displays Power Flow Vector.

From the IEEE Dictionary: "power-flow vector - Vector-
characterizing energy propagation caused by a wave and
giving magnitude and direction of power per unit-area
propagating in the wave."


Please note the "*DIRECTION OF POWER* ... *PROPAGATING*
in the wave", a direct contradiction to your above assertion.

The power measured at the source somehow finds its way to the
load in spite of not having any direction (according to you. :-)

Well, it's true for me and probably for most other people who have a
grasp of the subject. It's actually energy which does the moving.
Power is just the rate at which energy finds its way there.

It's like this. Let's say you're riding your Harley through town at 50
MPH and somebody pulls out of a side street right in front of you. Does
the speed of your motorcycle collide with the car, or does your
motorcycle collide with it?

73, ac6xg

On Wed, 20 Jul 2005 11:22:52 -0700, Jim Kelley
wrote:

Does
the speed of your motorcycle collide with the car, or does your
motorcycle collide with it?

Hi Jim,

Classic Insurance claim form entry:
"I was just driving down the road when, suddenly,
this tree appeared in front of me and hit me."

I think we have the same class of claimant in the process here.

73's
Richard Clark, KB7QHC

Jim Kelley wrote:

Cecil Moore wrote:
For engineers, the direction of the arrow for the Power
Flow Vector in joules/sec is generally accepted to be the
same as the direction of the joules.

I am an engineer, Cecil. I just happen to work in the field of physics.
I could be wrong, but I don't think a Bird wattmeter measures or
displays Power Flow Vector.

On the contrary, Jim, it measures and displays the Power Flow
Vector as explained in Ramo & Whinnery. The arrow on the slug
indicates the direction of the Power Flow Vector. The reading
of the meter indicates the magnitude of the Power Flow Vector.
The Bird is indirectly measuring [(E^for) x (H^for)] as forward
power and [(E^ref) x (H^ref)] as reflected power.

Well, it's true for me and probably for most other people who have a
grasp of the subject. It's actually energy which does the moving. Power
is just the rate at which energy finds its way there.

But everyone except you and a handful of others recognize the
fact that RF joules/sec and RF joules are virtually interchangeable
since EM energy cannot be stored in any condition other than as
EM energy traveling at the speed of light and real time cannot be
stopped or slowed down or speeded up (under normal circumstances).
Your statement that "there is no before and after" is a clue
to your misconceptions. If there truly was no before and after,
the modulation of our RF signals would never make it to the antenna.

It's like this. Let's say you're riding your Harley through town at 50
MPH ...

"I couldn't possibly be going 50 MPH - I only left home ten
minutes ago." :-) Believe it or not, that's exactly your argument.

Are you going to deny that the cross product of E^ x H^ is a
vector? You will have 1000 buried mathematicians rolling their
eyes in their graves (according to Richard C).
--
73, Cecil http://www.qsl.net/w5dxp


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Cecil Moore wrote:

Jim Kelley wrote:

Cecil Moore wrote:

For engineers, the direction of the arrow for the Power
Flow Vector in joules/sec is generally accepted to be the
same as the direction of the joules.


I am an engineer, Cecil. I just happen to work in the field of
physics. I could be wrong, but I don't think a Bird wattmeter measures
or displays Power Flow Vector.


On the contrary, Jim, it measures and displays the Power Flow
Vector as explained in Ramo & Whinnery. The arrow on the slug
indicates the direction of the Power Flow Vector. The reading
of the meter indicates the magnitude of the Power Flow Vector.
The Bird is indirectly measuring [(E^for) x (H^for)] as forward
power and [(E^ref) x (H^ref)] as reflected power.

Even though it doesn't actually measure any of those things, or the density.

Well, it's true for me and probably for most other people who have a
grasp of the subject. It's actually energy which does the moving.
Power is just the rate at which energy finds its way there.


But everyone except you and a handful of others recognize the
fact that RF joules/sec and RF joules are virtually interchangeable
since EM energy cannot be stored in any condition other than as
EM energy traveling at the speed of light and real time cannot be
stopped or slowed down or speeded up (under normal circumstances).
Your statement that "there is no before and after" is a clue
to your misconceptions. If there truly was no before and after,
the modulation of our RF signals would never make it to the antenna.

Yes. Everybody except me knows that Joules = Joules/sec. Must be
because there's no such thing as time. Right Cecil? ;-)

It's like this. Let's say you're riding your Harley through town at
50 MPH ...


"I couldn't possibly be going 50 MPH - I only left home ten
minutes ago." :-) Believe it or not, that's exactly your argument.

'Not' would be correct.

Are you going to deny that the cross product of E^ x H^ is a
vector? You will have 1000 buried mathematicians rolling their
eyes in their graves (according to Richard C).

I think I'll stick with just saying that power, as a scaler quantity
does not have direction and cannot be negative. I have no argument with
you about vector quantities - as much as you'd like folks to believe
that I do. Thanks but no thanks, bubba.

73, ac6xg

Jim Kelley wrote:
I think I'll stick with just saying that power, as a scaler quantity
does not have direction and cannot be negative.

So what is E^ x H^?
--
73, Cecil http://www.qsl.net/w5dxp

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Cecil Moore wrote:

Jim Kelley wrote:

I think I'll stick with just saying that power, as a scaler quantity
does not have direction and cannot be negative.


So what is E^ x H^?

According to Born and Wolf, it's "an abstraction that introduces a
certain degree of arbitrariness". On the other hand it's integral over
a volume is described as something from which "no unambiguous conclusion
can be drawn". So, is that what you're hangin' your hat on, there Cecil?

Or perhaps you would have preferred my response to be "it's whatever you
sez it is, massa mensa".

ac6xg

Jim Kelley wrote:

Cecil Moore wrote:
So what is E^ x H^?

According to Born and Wolf, it's "an abstraction that introduces a
certain degree of arbitrariness". On the other hand it's integral over
a volume is described as something from which "no unambiguous conclusion
can be drawn". So, is that what you're hangin' your hat on, there Cecil?

Actually, the Poynting Vector is extremely well defined *AND* well
accepted in the RF engineering community. Do you really reject the
Poynting Vector concept? If so, that explains everything.
--
73, Cecil http://www.qsl.net/w5dxp

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Cecil Moore wrote:
The Bird is indirectly measuring [(E^for) x (H^for)] as forward
power and [(E^ref) x (H^ref)] as reflected power.

That statement bears no physical relationship to how the instrument
actually works (and "indirectly" won't get you off the hook either).


--
73 from Ian G/GM3SEK 'In Practice' columnist for RadCom (RSGB)
http://www.ifwtech.co.uk/g3sek

Ian White G/GM3SEK wrote:

Cecil Moore wrote:
The Bird is indirectly measuring [(E^for) x (H^for)] as forward
power and [(E^ref) x (H^ref)] as reflected power.

That statement bears no physical relationship to how the instrument
actually works (and "indirectly" won't get you off the hook either).

I was hoping someone would assert such. E^for is proportional to
Vfor which is what the Bird samples. H^for is proportional to
Ifor which is what the Bird samples. Within a 50 ohm environment
that yields forward power. Same for reflected power.
--
73, Cecil http://www.qsl.net/w5dxp

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Cecil Moore wrote:
Ian White G/GM3SEK wrote:

Cecil Moore wrote:
The Bird is indirectly measuring [(E^for) x (H^for)] as forward
power and [(E^ref) x (H^ref)] as reflected power.
That statement bears no physical relationship to how the instrument
actually works (and "indirectly" won't get you off the hook either).

I was hoping someone would assert such. E^for is proportional to
Vfor which is what the Bird samples. H^for is proportional to
Ifor which is what the Bird samples. Within a 50 ohm environment
that yields forward power. Same for reflected power.

The Bird does not generate a vector cross product. There is nothing
inside the instrument that's capable of doing such a thing.

The hardware displays readings of detected RF voltages - not power. The
forward/reflected power calibration on the meter scale is an external
calculation, based on transmission line theory.

You know exactly how instruments like the Bird work, because at various
times you have posted accurate descriptions here. Your enthusiasm for
your pet theory is making you distort the truth.


--
73 from Ian G/GM3SEK 'In Practice' columnist for RadCom (RSGB)
http://www.ifwtech.co.uk/g3sek