A two-port network has scattering parameters given by $[S] = \begin{bmatrix}s_{11} &s_{12} \\s_{21} &s_{22} \end{bmatrix}.$ If the port-2 of the two-port is short circuited, the $s_{11}$ parameter for the resultant one-port network is
- $\dfrac{s_{11} – s_{11}s_{22} + s_{12}s_{21}}{1+s_{22}} \\$
- $\dfrac{s_{11} + s_{11}s_{22} – s_{12}s_{21}}{1+s_{22}} \\$
- $\dfrac{s_{11} + s_{11}s_{22} + s_{12}s_{21}}{1 – s_{22}} \\$
- $\dfrac{s_{11} – s_{11}s_{22} + s_{12}s_{21}}{1 – s_{22}}$