Walter Maxwell wrote:
I'm trying to locate my Hecht paper, but can't at the moment. Let's make sure
we're talking about the same set of of equations. The ones I'm saying are
invalid as stated in his article appear on Page 46, Col 2.

Walt, I'm sorry, all I have is the QEX CD and the pages are not the same as
they were in QEX magazine. Dr. Best's equations 13 and 15 are the classical
physics interference equations virtually identical to the irradiance equations
in _Optics_, by Hecht.

But Cecil, you CAN'T add V1 and V2 in any manner to obtain forward power,
because adding V1 and V2 does not yield forward voltage.

Yes, it does, Walt. Consider the following matched system similar to the
example in Dr. Best's article.

100w XMTR-----50 ohm line---x---1/2WL 150 ohm line---50 ohm load

P1 = 100W(1-rho^2) = 100(1-.25) = 75W

P2 = 33.33W(rho^2) = 33.33W*.25 = 8.33W

P1 = 75W, P2 = 8.33W, PFtotal = 133.33W

V1 = 106.07V, V2 = 35.35V, VFtotal = 141.4V

V1 + V2 = VFtotal, 106.07V + 35.35V = 141.4V

How many times do I have to explain that V1 + V2 does NOT equal VF total?

But it does, Walt. See above.

75w + 8.33W + 2*SQRT(75W*8.33W) = 133.33W (Equation 13)

This is Steve's Eq 12, which appears to be correct when theta = zero, but he
qualifies this equation, saying that when V1 and V2 are in phase the total
power can be determined by Eq 13. NOT SO.

Yes, it is, Walt. Equation 13 is valid for any matched system. That's
equation 13 just above. Perhaps you don't understand what Dr. Best means
by P1 and P2.

PFtotal = P1 + P2 + 2*SQRT(P1*P2) total forward power

133.33W = 75W + 8.33W + 50W

There's 50W of constructive interference and the equation balances perfectly.
--
73, Cecil http://www.qsl.net/w5dxp



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