Re: Mismatched Zo Connectors

Cecil Moore wrote:

How does a wave know whether to
carry energy or not depending upon its future fate?

Does a laser beam reflected from an ideal mirror carry any
less energy than the forward beam just because it has been
reflected?

What can be said other than; these questions appear to have been posed by someone who is struggling to understand some pretty simple concepts.

> In a one second long lossless transmission line, watts
> equal joules. A forward wave of 200 watts contains 200
> joules of energy. A reflected wave of 100 watts contains
> 100 joules of energy. Under such conditions, the source
> has supplied exactly 300 joules more than has been
> delivered to the load, no more and no less.

Is your claim that the above describes the system with, or without, the circulator load?


Yes, in both cases the voltage reflection coefficient
at the load is 0.707 making the power reflection
coefficient = 0.5, i.e. half the power incident upon
the load is reflected.

But, is the latter really more than a mathematical convenience? (You may recall that 'power' isn't something which actually moves in physical systems. And being a scalar, it can be tricky to do a proper vector analysis.) How energy moves is dependent upon factors throughout the entire system - not just at the load.

The system with the circulator load at the signal
generator has the signal generator supplying 200
watts and the circulator load resistor dissipating 100
watts. 'SGCR' stands for a signal generator equipped with
a circulator and circulator load resistor equal to the
Z0 of the feedline. There's 300 joules of energy in the
feedline during steady-state. 100 watts is dissipated
in the load.

200W SGCR-----one second long feedline-------load
Pfor=200W--> <--Pref=100W

The system without the circulator and load consists of
a 100 watt source feeding an ideal autotuner tied to
the transmission line. In this case all reflected energy
is re-reflected by the Z0-matched autotuner. 'SGAT' stands
for a signal generator equipped with an ideal autotuner.
There's 300 joules of energy in the feedline during
steady-state. 100 watts is dissipated in the load.

100W SGAT-----one second long feedline-------load
Pfor=200W--> <--Pref=100W

Very inventive. The question was posed without a load on the circulator, not without a circulator. You still haven't answered that question. Perhaps you wouldn't mind just considering one system at a time. No sense changing the variables just to make the solution come out the way we want. Don't they teach you that you're not supposed to change horses in the middle of a stream out there in Texas? ;-)

So, since we've obviously been talking about the steady state, what's with all the weird questions about 'how the wave knows' what's going to happen in the future?

73, ac6xg


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Relevant Pages

  • Re: Mismatched Zo Connectors
    ... carry energy or not depending upon its future fate? ... Energy at the speed of light has no time dimension and as ... at the load is 0.707 making the power reflection ... the load is reflected. ...
    (rec.radio.amateur.antenna)
  • Re: The Extreme Failure of Poor Concepts in Discussing Thin Layer ...
    ... The incident wave traveling on the coax has too much voltage and too little current to supply the 25-ohm load. ... The rearward-traveling reflected wave sees the impedance discontinuity at the match point and 1/2 of the energy is reflected back toward the load according to the rules of reflection. ...
    (rec.radio.amateur.antenna)
  • Re: Transmitter Output Impedance
    ... not the same mismatch as between the line and the load. ... The mismatch, of the reflection wave approaching the transmitter, is ... then that energy must travel to meet a matching load ...
    (rec.radio.amateur.antenna)
  • Re: Standing-Wave Current vs Traveling-Wave Current WAS rraa Laugh Riot continues
    ... What causes 100% reflection when the power reflection ... The only energy "lost" by partial reflection in the process is that which is reflected back toward the source or stored in the system during the transient period. ... The sum of all the partial reflections equals the energy stored in the system (less the portion of energy admitted to the load or reflected back to the source). ...
    (rec.radio.amateur.antenna)
  • Re: Mismatched Zo Connectors
    ... load and therefore, I must contain N joules of energy." ... "I am not going to be dissipated in a circulator ... Please present us with a set of Black Boxes that will ...
    (rec.radio.amateur.antenna)