Understanding the Practical Application of H-Parameters in Circuit Analysis

[ranju]

While solving for h-parameters ..we take certain assumptions like , open circuiting input & short circuiting output..how can we see this thing practically..?? I mean..If we are ssaying that if output is shortcuited then h11=V1/I1 =input impedence with output short-circuited..if output is not short-circuited,,then will this have no relevance..??
Please explain what does this actually means?

 

[NascentOxygen]

If output is not s/c then there are multiple elements in the model that influence the input current, as you can see in this wikipedia figure.

But if you s/c the output, making V₂ = 0, then the voltage source affecting the input becomes null, thus leaving h₁₁ as the only influence on input current. So by measuring input current under this condition, when you apply a test voltage you can determine a value for that h₁₁ resistance.