10.2 OPEN CIRCUIT IMPEDANCE OR [Z] PARAMETERS

Now if I ₁ = 0 means the input port is an open circuit

and

if

I ₂ = 0 means the output port is an open circuit

and

Figure 10.2: Determination of Z-parameters

[Z] parameters are known as open circuit impedance parameters because, in both the cases, one port is open (i.e., I ₁ = 0 and I ₂ = 0)

Z ₁₁ and Z ₂₂ are driving-point impedance at port 1 and port 2. In the case of driving-point function the data should be from the same port.

Z ₁₂ and Z ₂₁ are transfer impedance because in Z ₁₂ and Z ₂₁; one data is from port 1 and the other data is from port 2,

Z ₁₂ [V ₁ from port 1 and I ₂ from port 2] = reverse transfer impedance

Z ₂₁ [I ₁ from port 1 and V ₂ from port 2] = forward transfer impedance.

It is seen that dimensionally each parameter is an impedance (ratio voltage and current), therefore, the impedance parameters may be either calculated or measured by first opening port 2 and then determining the ratios and , and then opening port 1 and determining the ratios and . But in this chapter we will solve all problems using the comparing method.