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