On Jan 1, 12:20*pm, Roger wrote:
Keith Dysart wrote:
On Dec 30, 5:30 pm, Roger wrote:

I don't recall any examples using perfect CURRENT sources. *I think a
perfect current source would supply a signal that could respond to
changing impedances correctly. *It should solve the dilemma caused by
the rise in voltage which occurs when when a traveling wave doubles
voltage upon encountering an open circuit, or reversing at the source.

What do you think?

A perfect current source has an output impedance of
infinity, just like an open circuit. The reflection
coefficient is 1.

Similar to the reflected voltage for the perfect
voltage source, the reflected current cancels leaving
just the current from the perfect current source.

...Keith

This disagrees with Roy, who assigns a -1 reflection coefficient when
reflecting from a perfect voltage source.

I don't think there is disagreement...
- perfect current source, infinite output impedance,
equivalent to open circuit, RC = 1
- perfect voltage source, zero output impedance,
equivalent to short circuit, RC = -1
- output impedance equal to Z0, RC = 0
- output impedance greater than Z0, RC 0
- output impedance less than Z0, RC 0

The Norton or Thévenin equivalent circuits seem *capable of positive
reflection coefficients. *

Either can be positive, negative, or zero depending
on the value of the output impedance compared to Z0.

That is all that I am looking for.

Your search suggestion from a different posting '"lattice diagram"
reflection'yields some examples that demonstrate positive reflection
coefficients.

This would only be because the examples happened to use
output impedances greater than Z0.

I must have missed something, because I can't understand why there is an
insistence that a negative reflection coefficient must exist at the
source for the 1/2 or 1 wavelength long transmission line fed at one end.

The reflection coefficient depends on the values of line
characteristic impedance (Z0) and the output impedance of the
source.

Recall that RC = (Z2-Z1)/(Z2+Z1)

For the reflected wave arriving back at the source,
Z1 is the characteristic impedance of the line (Z0)
and Z2 is the output impedance of the source.

...Keith