Cecil Moore wrote:
wrote:
But without some equations defining Pfwd and Prev, the concept is
not particularly useful since there are no predictions which you
can make from it.
The equations are to be found in Dr. Best's Nov/Dec 2001 QEX article,
"Wave Mechanics of Transmission Lines: Part 3" and in _Optics_, by
Hecht. When the characteristic impedances are real:
Do recall that this discussion started with a line whose characteristic
was complex not real, so all that follows here is moot.
V1 = Vfwd1(tau1) V2 = Vref2(rho2) V3 = Vfwd1(rho1) V4 = Vref2(tau2)
Vfwd2 = V1 + V2 Vref1 = V3 + V4
P1 = Pfwd1(1-|rho|^2) P2 = Pref2(|rho|^2) forward components
P3 = Pfwd1(|rho|^2) P4 = Pref2(1-|rho|^2) reverse components
Pfwd2 = P1 + P2 + 2*Sqrt(P1*P2)cos(delta-1)
Pref1 = P3 + P4 + 2*Sqrt(P3*P4)cos(delta-2)
where (delta-1) is the angle between V1 and V2, (delta-2) is the angle
between V3 and V4, and that last term is called the interference term.
In _Optics_, average power is called irradiance (I) and the equation is:
I1 + I2 + 2*Sqrt(I1*I2)cos(delta)
For further information, check out my Part 1 energy analysis article
on my web page. Part 2 will appear shortly.
But, going back to the original question, is Pfwd and Prev on a line
with complex Z0?
....Keith