In this article we will study about h-Parameter of two port network.

h-Parameter representation is widely used in modelling of electronic components and circuits, particularly transistors.

h-Parameter is called "Hybrid Parameter".

In h-Parameter, the input voltage and output current are function of input current and output voltage respectively.

Y-Parameter is also called "Short Circuit Parameter" and "Admittance Parameter".
In Y-Parameter, the input and output currents are function of input and output Voltages.
( I1 , I2 ) = f ( V1 , V2 )
It can also be written as:
[I] = [Y]   [V]
where [Y] represents Admittance Matrix.
In matrix form,
[I1] =    [Y11  Y12]   [V1]
[I2] =    [Y21  Y22]   [V2]
Writing it in equation,
I1 = Y11* V1 + Y12* V2 .........eq1
I2 = Y21* V1 + Y22* V2 .........eq2
CASE-1 SHORT CIRCUITING THE OUTPUT PORT
If the Output port of the two port network is  short circuited then output voltage is zero, i.e. V2 = 0.
Now, equation 1 and 2 will be reduced to :
I1 = Y11* V1
I2 = Y21* V1
So, Y11 = I1 /V1    ( keeping v2 = 0 )
      Y21 = I2/ V1    ( keeping V2 = 0 )
CASE-2 SHORT CIRCUITING THE INPUT PORT
If the Input port of the two port network is short circuited then the input voltage is zero, i.e. V1 = 0.
Now, equation 1 and 2 will be reduced to :
I1 = Y12* V2
I2 = Y22* V2
So, Y12 = I1/ V2    ( keeping V1= 0 )
       Y22 = I2/ V2  ( keeping V1 = 0 )
Y11 is called input driving point Admittance.
Y12 is called forward transfer Admittance.
Y21 is called reverse transfer Admittance
Y22 is called output driving point Admittance.
For a network to be symmetrical , Y11 = Y22
For a network to be reciprocal, Y12 = Y21
EQUIVALENT CIRCUIT OF Y-PARAMETER

Z-Parameter is also called "Open Circuit Parameter" and "Impedance Parameter".
In Z-Parameter, the input and output voltage are function of input and output current.
( V1 , V2 ) = f ( I1 , I2 )
It can also be written as:
[V] = [Z][I]
Where Z represents Impedance Matrix.
In matrix form
[V1] =    [Z11  Z12]   [I1]
[V2] =    [Z21  Z22]   [I2]
Writing it in equation,
V1 = Z11* I1 + Z12* I2 .........eq1
V2 = Z21* I1 + Z22* I2 .........eq2
CASE-1 OPEN CIRCUITING THE OUTPUT PORT
If the Output port of the two port network is open circuited then the output current is zero, i.e. I2 = 0.
Now, equation 1 and 2 will be reduced to :
V1 = Z11* I1
V2 = Z21* I1
So, Z11 = V1/ I1    ( keeping I2 = 0 )
Z21 = V2/ I1  ( keeping I2 = 0 )
CASE-2 OPEN CIRCUITING THE INPUT PORT
If the Input port of the two port network is open circuited then the input current is zero, i.e. I1 = 0.
Now, equation 1 and 2 will be reduced to :
V1 = Z12* I2
V2 = Z22* I2
So, Z12 = V1/ I2    ( keeping I1 = 0 )
Z22 = V2/ I2  ( keeping I1 = 0 )
Z11 is called input driving point Impedance
Z12 is called forward transfer Impedance
Z21 is called reverse transfer Impedance
Z22 is called output driving point Impedance.
For a network to be symmetrical , Z11 = Z22
For a network to be reciprocal, Z12 = Z21
EQUIVALENT CIRCUIT OF Z-PARAMETER