What is two- port parameter h 12?

Two-port parameter ( h_{12} ), also known as the reverse voltage gain or the transfer parameter, represents the relationship between the output voltage ( V_2 ) and the input current ( I_1 ) in a two-port network. Specifically, it is defined as ( h_{12} = -\frac{V_2}{I_1} ) when the output port is open-circuited (i.e., ( I_2 = 0 )). In practical terms, it indicates how changes in the input current affect the output voltage, highlighting the interdependence of input and output in the network's behavior.