Walter Maxwell wrote:
Cecil, please read me in the first paragraph. By Steve's own words he says the
re-reflected wave must equal the reflected wave.

No, he says that is a fallacy. He says the re-reflected wave equals the
reflected wave multiplied by the reflection coefficient. His example is:
reflected power = 33.33W, re-reflected power = 8.33W

re-reflected power = 33.33W(rho^2) = 33.33W(0.25) = 8.33W
Here's what Dr. Best said in his QEX article, Part 3: "When two forward-traveling
waves add, general superposition theory ... require(s) that the total forward
traveling voltage be the vector sum of the individual forward-traveling voltages
such that VFtotal = V1 + V2." He clearly implies that V2 is a forward-traveling
wave and it is. Numerically, it is equal to the voltage reflected from the load
multiplied by the reverse reflection coefficient. In S-parameter terms, V2 is
the s22(a2) term.

Concerning tau, I've seen it described in an HP App Note, which I didn't bring
to Michigan, but I've never used it. However, if the power transmission
coefficient is (1 - rho^2) the coefficient is 0.75 for rho = 0.5. Therefore, for
100 w forward only 75 w are delivered. This condition is shown valid
experimentally.

Yes, 100W(0.75) is perfectly consistent with 70.7V(1.5)^2/150 where Z0=150 ohms

Now let's use tau = 1 + rho as the voltage transmission coefficient. I interpret
this to mean tau x input voltage = forward voltage arriving at a mismatched
load.

No, no, no. Mistaken interpretation.

tau x input voltage = V1 (not the total forward voltage)

rho x reflected voltage = V2 (re-reflected)

V1 + V2 = forward voltage arriving at a mismatched load

V1 is proportional to the S-parameter term, s21(a1) where s21 is the forward-transmission
coefficient.

V2 is proportional to the S-parameter term, s22(a2) where s22 is the reverse-reflection
coefficient.

b2 is the total forward voltage arriving at a mismatched load.

VFtotal = V1 + V2 is virtually identical to b2 = s21(a1) + s22(a2)
--
73, Cecil http://www.qsl.net/w5dxp



-----= Posted via Newsfeeds.Com, Uncensored Usenet News =-----
http://www.newsfeeds.com - The #1 Newsgroup Service in the World!
-----== Over 100,000 Newsgroups - 19 Different Servers! =-----