RadioBanter - View Single Post - Derivation of the Reflection Coefficient?

September 2nd 03, 11:57 PM

In article ,
(Dr. Slick) wrote:

"David Robbins" wrote in message
...
From 'Fields and Waves in Communications Electronics' by Ramo Whinnery and
Van Duzer. section 1.16 and 1.23

start with positive moving wave plus negative moving wave = total to load
for both voltage and current, simple kirchoff's law summations at the
junction of the coax and load.
Vp+Vn=Vload (1)
Ip-In=Iload (2)
note that their convention is that current moving to the 'right' is positive
so the reflected 'negative' current wave is moving left which gives the
negative sign on the second term.

now use ohm's law to rewrite (2)

Vp/Zo - Vn/Zo = Vload/Zload (3)

I believe this line (3) is only true if Zo is purely real.

If Zo is complex, i don't think you can apply
this.

I swore that I wouldn't get into this one, but enough's enough.

Equation (1) is an application of Kirchoff's voltage law.
Equation (2) is an application of Kirchoff's current law.
Equation (3) results from (2) if you apply Ohm's law three times, to the
three terms in Equation (2).

Which of these three principles (Kirchoff's voltage law, Kirchoff's
current law, or Ohm's law) is the one you don't believe? Or do you
disbelieve more than one of the three?

David, ex-W8EZE

--
David or Jo Anne Ryeburn

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