What does a complex reflection coefficient signify?

[matrixofdynamism]

A reflection coefficient (Г) of 0 means that all power is absorbed by load. This happens when both source and load impedance are equal.
A reflection coefficient (Г) of 1 means that all power is reflected by load. This happens if the load is open circuit.

What does a complex value of reflection coefficient mean?

I do understand that the reflection coefficient can be positive or negative, if the reflection is inverted signal relative to the source, then the reflection coefficient must be negative. What I don't understand is what does a complex reflection coefficient mean. I wonder if it has something to do with phase difference, but that really will be even more confusing if it really is the case.

 

[BigBoss]

Gamma=Zin-Zs/(Zin+Zs)

Zs and Zin are complex so the reflection coefficient is also complex.

Magnitude of the Reflection Coefficient cannot be negative.It's always between 0 and 1.

 

[FvM]

Read about Smith chart. It's an intuitive way to understand complex reflection coefficients.

 

[PlanarMetamaterials]

I do understand that the reflection coefficient can be positive or negative, if the reflection is inverted signal relative to the source, then the reflection coefficient must be negative. What I don't understand is what does a complex reflection coefficient mean. I wonder if it has something to do with phase difference, but that really will be even more confusing if it really is the case.

In addition to the above comments -- similar (and related) to a complex impedance, a complex reflection coefficient means that reflection is caused by a load that has both real and imaginary components. As you indicated, this results in a reflection phase that is not 0 or 180 degrees.

 

[zorro]

All the above is right (except for a missing pair of parenthesis for (Zin-Zs) in post #2), but the essential concept should be emphasized:

The reflection coefficient is the ratio reflected_wave/incident_wave. Both waves are complex magnitudes (phasors).

Its modulus is the ratio of amplitudes (real and positive).
Its phase can be viewed as the angle between both phasors.

Regards

Z

 

[matrixofdynamism]

I was not talking about the magnitude of the reflection coefficient. The coefficient iteslf which is Г=Zin-Zs/(Zin+Zs), can be both positive or negative. It can be purely imanigery as well and in this case it can be positive imaginary as well as negative imaginary.

 

[zorro]

Please read my post #5:

a) Don't miss parenthesis in Г=(Zin-Zs)/(Zin+Zs)

b) Г is the quotient of two complex numbers (representing reflected and incident waves), so it is a complex number. It has modulus and phase. It has both real and imaginary part, and both of them can be positive or negative.

Z