10.3 SHORT CIRCUIT ADMITTANCE OR [Y] PARAMETERS

Now if V ₁ = 0 the input port is short circuit

and

if V2 = 0 the output port is short circuit

Figure 10.5: Determination of Y-parameters

[Y] parameters are known asshort circuit admittance parameters because in both the cases, one-port is short (i.e., V ₁ = 0 and V ₂ = 0). The constants Y ₁₁, Y ₁₂, Y ₂₁, and Y ₂₂ are called the admittance or Y-parameters of the two-port network. Equations (10.3) and (10.4) are called the standard equation or defining equations of the Y-parameters.

Y ₁₁ and Y ₂₂ are driving-point admittance at port 1 and port 2.

Y ₁₂ and Y ₂₁ are known as transfer admittance.

Y ₁₁ is known as short circuit input admittance.

Y ₁₂ is known as short circuit reverse transfer admittance.

Y ₂₁ is known as short circuit forward transfer admittance.

Similarly, Y ₂₂ is known as short circuit output admittance.

It is seen that dimensionally each parameter is admittance (ratio of current and voltage). Also, each parameter is obtained by short circuiting either the input or output port. Therefore, these parameters are called the short circuit admittance parameters. The admittance parameters may be either calculated or measured by first shorting port 1 and then determining the ratios ( ) and ( ), and then shorting port 2 and determining the ratios ( ) and (