Question 17.8: The t-parameters of a two-port network are A = –1, B = j50 Ω......

The i-ν relationships of the two-port network are

V_{1} =- V_{2} + j50 (-I_{2})
I_{1} = j20 × 10^{-3}V_{2}

The 50-Ω resistor connected at the output means that V_{2} = 50( -I_{2}). Substituting this constraint into the two-port i-ν characteristics yields the input impedance as

Z_{IN} = \frac{V_{1}}{I_{1}}=\frac{-50( -I_{2})  +  j50( -I_{2})}{(j20  ×  10^{-3})50 (-I_{2})}= 50 + j50  Ω