Two-port network transmission parameters?

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Discussion Overview

The discussion revolves around the transmission parameters of two-port networks, specifically focusing on the t-parameters (or A-parameters). Participants are exploring the relationships between different network parameters, including capacitance, inductance, resistance, and admittance, while attempting to solve a homework problem related to these concepts.

Discussion Character

  • Homework-related
  • Technical explanation
  • Exploratory
  • Debate/contested

Main Points Raised

  • One participant discusses their approach to finding equivalent capacitance and inductance, indicating confusion with parametric equations and nodal analysis.
  • Another participant questions the units of capacitance provided in the problem, suggesting a possible error in the expression of capacitance as millifarads instead of microfarads.
  • A participant proposes a method to derive t12 using resistance values, suggesting that t12 can be interpreted as the resistance value based on the relationship between voltage and current.
  • There is mention of the equations for the ABCD parameters in terms of currents and voltages, with a request for clarification on these equations.
  • One participant expresses uncertainty about how to derive the remaining matrix elements for the admittance Y(s) and seeks guidance on this process.
  • A later reply suggests using a transformation from Y parameters to t parameters, referencing an external resource for a table of transformations.

Areas of Agreement / Disagreement

Participants express varying levels of understanding and confusion regarding the relationships between different parameters and the correct approach to solving the problem. There is no consensus on the correct method or values to use, and multiple competing views remain regarding the interpretation of the parameters.

Contextual Notes

Participants have not fully resolved the assumptions regarding the definitions of the parameters and the specific values to use in their calculations. There are also unresolved questions about the correctness of the units and the structure of the matrices.

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two-port network transmission parameters??

Homework Statement


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Homework Equations


t[A B]=[t11 t12]
[C D]=[t21 t22]

The Attempt at a Solution


so, first thing i did was find the equivalent capacitance/inductance. C(eq)=-j0.5 and L(eq)=j0.5.
using these values as I was confused by parametric equations in general i decided to do nodal equations. using V1 as the node left of resistance R, V2 as the one right of it. since in my book, they do nodal equations to check the values of y-paramter matrices.

V1 equation: (1+j2)V1+(-1)V2=0
V2 equation: (-1)V1+(1-j2)V2=0

since the t equation (choice A) had different sign values than the nodal matrix, i guessed this was wrong. choice B also looked wrong because it only had the C(eq) value, so I chose choice D because that looked similar to (1-j2)V2 in the equation for V2. i obviously know i am doing this wrong.EDIT: looking over my notes i think this is a 't-parameter' problem. According to my teacher, the T-parameter matrices for each of the following:
Z(ohm) [T] matrix:
Code:
[1  z]
[0  1]

Y(s) [T] matrix:
Code:
[1  0]
[Y  1]

where Z and Y are the values. i am assuming Z if for resistor or any real value, Y is for imaginary part and I think the admittance. i still don't know why the matrices are structured like this, though. but if i assume this is correct, choices B, C, and D are all wrong because they don't follow the format. that leaves only A.
 
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question 1: it says "C = 10 mF". Do they really mean 10 mF or do they mean 10 uF? It is most uncommon to express capacitance in millifarads.

Now: you need to know the two equations for the ABCD parameters in terms of i1, i2, V1 and V2 for each section t, t1 and t2. What are they?

OR: find the Z, Y or other parameters for each section and then translate to ABCD parameters.
 
i think i know how my teacher got t12. suppose R=3ohm, t12=V1/-I2, and -I2 is just 1V/3ohm, then 1V/-I2 would just flip it and give you the value of resistance. another way is since t12 is in units of ohms, it would just be resistance value. t21 is in units of (S) so it would just be admittance for Y(s). and i do have the equations for V1/I1/V2/I2 but i think my main problem is i don't know what values to use. it is also the only other way my book lists to find the other matrix elements.
V1=I1+0I2
V2=1I1+0I2

solve V2 equation for I1:
1I1=V2-0(I2)
so t21 and t22 should be 1 and 0. but the opposite is true.

plug in I1 into V1 equation:
V1=1(V2)+1(I2)
which gives t11=1 and t12=R..?

also, I still don't understand how to get the rest of the matrix elements for the admittance Y(s). I know t21 is in units of (S), so it should be Y, but that's as far as I get.
 
You already have the Y parameters. As rude man suggested, use the transformation from Y to t parameters.

You can find a table of transformations (the t parameters are also known as a parameters) here:

http://en.wikipedia.org/wiki/Two-port_network

near the bottom of the page.
 

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