For a two-port network, V₁ and V₂ are given by

V₁ = 60I₁ + 20I₂

V₂ = 20I₁ + 40I₂

The Y-parameters of the network are

Y (Admittance) Parameters:

They are also called the short circuit parameters, as they are calculated under short circuit conditions, i.e. at V1 = 0 and V2 = 0.

Expressed in Matrix Form as:

$\left[\begin{array}{c}{I}_1\\ I_2\end{array}\right]=\left[\begin{array}{cc}{Y}_{11}& Y_{12}\\ Y_{21}& Y_{22}\end{array}\right]\left[\begin{array}{c}{V}_1\\ V_2\end{array}\right]$

I1 = Y11V1 + Y12V2

I2 = Y21V1 + Y22V2

With the output short-circuited, i.e. V2 = 0, the two parameters obtained are:

$Y_{11}={\frac{I_1}{V_1}|}_{V_2=0}$

$Y_{21}={\frac{I_2}{V_1}|}_{V_2=0}$

With the input short-circuited, i.e. V1 = 0, the two parameters obtained are:

$Y_{12}={\frac{I_1}{V_2}|}_{V_1=0}$

$Y_{22}={\frac{I_2}{V_2}|}_{V_1=0}$

Analysis:

V1 = 60I1 + 20I2

V2 = 20I1 + 40I2

This is in the form of Z - parameters i.e. 

Z₁₁ = 60, Z₁₂ = 20, Z₂₁ = 20, Z₂₂ = 40

$\left[\begin{array}{c}{V}_1\\ V_2\end{array}\right]=\left[\begin{array}{cc}{Z}_{11}& Z_{12}\\ Z_{21}& Z_{22}\end{array}\right]\left[\begin{array}{c}{I}_1\\ I_2\end{array}\right]$

$Y={\left[\begin{array}{cc}{Z}_{11}& Z_{12}\\ Z_{21}& Z_{22}\end{array}\right]}^{-1}$

$Y=\frac{1}{Z_{11}{Z}_{22}-Z_{12}{Z}_{21}}\left[\begin{array}{cc}{Z}_{22}& -Z_{12}\\ -Z_{21}& Z_{11}\end{array}\right]$

$$$Y=\frac{1}{60\times 40-20\times 20}\left[\begin{array}{cc}40& -20\\ -20& 60\end{array}\right]$

Y₁₁ = 20 × 10^-3

Y₁₂ = -10 × 10^-3

Y₂₁ = -10 × 10^-3

Y₂₂ = 30 × 10^-3