About Us

September 10th 03, 12:11 AM

wrote in message ...

Well, there is no phasor notation in your overly simplistic
example. So we don't see the forward and reflected waves.

If you follow back through the posts you will find that this
started with phasors.

You wrote:

Let us apply 1 volt to this circuit...
Total impedance
50+j200+0-j200 = 50 ohms
Total current (volts/impedance)
1/50 = .02 A
Voltage across resistor
.02 * 50 = 1 V
Voltage across inductor
.02 * (0+j200) = 4/_ 90 Volts
Voltage across capacitor (the load)
.02 * (0-j200) = 4/_ -90

Now for the check...
Vi = 0.5 V
With classic rho
Vr = 0.5 * 8.062/_ -97.125 = 4.031/_ -97.125
Vload = Vi+Vr = 0.5 + 4.031/_ -97.125 = 4/_ -90
The same as computed using circuit theory.

So your Vi is a DC voltage here, not a phasor.

Right, but if you are going to compare...how does circuit
theory give you Vr = 0.5 * 8.062/_ -97.125 = 4.031/_ -97.125?

This would convince me quite a bit, if you could derive this
with circuit theory.

I am unsure what you mean here. The equation Vr = Vi * rho is
used in both cases. In one, 'revised rho' is used. In the other,
'classic rho' is used. The results with 'revised rho' do not
agree with results from circuit theory. Does this not cast
some doubt on the validity of 'revised rho'?

Circuit theory may be wrong.

You never derived how circuit theory gives you
Vr = 0.5 * 8.062/_ -97.125 = 4.031/_ -97.125?

Or not understood.

The questioner possed a question. The answerer provided two answers
depending on how the question was interpreted. Wath's the problem?

The problem is you don't really know the answer either, that's for
certain, but you are responding as if you did.

Very nice dancing around the point, Keith!

You're more confused than me!

It does seem that I am having some difficulty conveying the concept.

Just because a thing has a name, does not mean the name accurately
describes the thing.

Just because you can use a few fancy RF terms, doesn't mean you
understand them fully.

I'll agree that power meters recitify the signal, and actually get
a DC voltage from the line. In a certain sense, they are more like
RMS voltmeters than power meters.

I'd like to see ANY power RC over 1 for a passive network,
please show us the circuit to build on the bench!

The passive network you provided in your first post fulfills this
requirement if you define 'power RC' as |rho|^2.

I disagree that the voltage RC will be greater than 1.

The tricky part is measuring this correctly, because you
would need an SWR meter that is calibrated for the same Z as
Zo.

Slick

Thread Tools	Search this Thread
Show Printable Version	Search this Thread: Advanced Search
Display Modes
Switch to Linear Mode Switch to Hybrid Mode Threaded Mode

Menu

About Us