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Jim Kelley wrote:
As I said, Cecil, your ideas about waves 'possessing energy' need a little work. All it takes to prove you wrong is a look at a typical S-Parameter equation involving the superposition of two terms. In the following the '@' sign is used for the angle sign. a1 and a2 are normalized voltages. s21 is a transmission coefficient. s22 is a reflection coefficient. b2 = s21(a1) + s22(a2) Given a1 = 10 @ 0 deg, a2 = 10 @ 180 deg, s21 = 0.707 @ 0 deg, s22 = 0.707 @ 180 deg s21(a1) = 0.707@0(10@0) = 7.07 @ 0 deg s22(a2) = 0.707@180(10@180) = 7.07 @ 0 deg superposing those two values gives: b2 = 14.14 @ 0 deg All is well and good. Multiply b2 by SQRT(Z0) to get total forward voltage. Now let's look at the powers in accordance with HP's Ap Note 95-1. For that, we don't need to know the Z0. The beauty of an S-Parameter analysis is that if one squares the normalized voltages, one gets power. |s21(a1)|^2 = 50 watts |s22(a2)|^2 = 50 watts |b2|^2 = 200 watts Even in the S-Parameter analysis, superposing two 50W waves in phase yields 200 watts. Constructive interference not only makes it possible but demands it. Jim, I challenge you to find anything wrong with this S- Parameter analysis. It follows exactly Born and Wolf's intensity equations for constructive interference when the phase angle between a1 and a2 is 180 degrees and their magnitudes are equal. -- 73, Cecil http://www.w5dxp.com |
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