# ABCD Matrix of transmison line

1. Apr 27, 2015

### baby_1

Hello
I want to obtain ABCD matrix element value.At first I tried to find A element value with boundary conditions but I don't know how can I find relationship between V(1)+ and V(1)- .

Any help appreciate

2. Apr 27, 2015

### rude man

Do you know how to determine the reflection coefficient ρ at position 1? 'Cause that's what Vo1-/Vo1+ is.
A convenient way to find ρ is to put the source at z = 0 and the load at z = L where L is the physical length of the transmission line.

3. May 4, 2015

### baby_1

Thank you dear rude man
Before post this thread I think that I can use reflection coefficient too but as you know I don't have any other information before point 1 and my Z0 in this equation is unknown.

4. May 4, 2015

### rude man

In post 1 you seem to state that Z0 was known. Anyway, it has to be known or you can't find the abcd parameters.

5. May 4, 2015

### baby_1

Thank you for accompany me
Here is my question we don't have any information before Point 1(Z1) how can define relationship between V+ and V-?

6. May 5, 2015

### rude man

I'm having trouble understanding what you say and what you write.
V1 = V2+e + V2-e-jθ
V2 = V2+ + V2-
Γ2 = V2-/V2+ = (Z2 - Z0)/(Z2 + Z0).
Z2 = V2/I2
You can eliminate the + and - waves using the above.
And there are similar equations for I1, I2+ and I2-.
You wind up with
V1 = AV2 + BI2
I1 = CE2 + DI2
where A, B, C and D contain only θ and Z0.

Last edited: May 5, 2015