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Old April 15th 07, 02:56 PM posted to rec.radio.amateur.antenna
Cecil Moore[_2_] Cecil Moore[_2_] is offline
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First recorded activity by RadioBanter: Mar 2007
Posts: 3,521
Default Constructive interference in radiowave propagation

Jim Kelley wrote:
Partially reflective surfaces can (and are) in fact used to prevent
reflections, just as they are used to 100% re-reflect partial
reflections from a load.


Let's look at one of those reflective surfaces from
the standpoint of the forward wave in an S-Parameter
analysis.

a1----|
|----s21(a1)
s11(a1)----|

a1 is the normalized forward voltage, e.g. 10
s11 is the voltage reflection coefficient, e.g. 0.707
s21 is the voltage transmission coefficient

|a1|^2 is the forward power called Pfor1 in my energy
analysis article.

|s11(a1)|^2 is the reflected power called P3 in my
energy analysis article.

|s21(a1)|^2 is the transmitted power called P1 in
my energy analysis article.

The point is that s11(a1) is a steady-state value for
normalized reflected voltage that never makes it through
the impedance discontinuity.

|s11(a1)|^2 is the steady-state reflected joules/sec
that never makes it through the impedance discontinuity.

Here is a fill in the blank question for you and anyone
else who wants to respond.

If a Z0-match exists, the above values of normalized voltage
and joules/sec do not reach the source during steady-state
because __________________________________________________ _.
--
73, Cecil http://www.w5dxp.com