# Two-port network and h-parameters - How to find them for this circuit

#### gianx80

Joined Jan 23, 2011
14
Hi,
I'm studying for my master's degree in Computer Science and I also need to take a couple of exams included in another bachelor's degree. I'm also a full time worker, so it's not an easy task to accomplish.

I have this circuit:
I have to:
1. find h-parameters for this network
2. find the absorbed power using the h-parameter
The two ports of this network are the terminals of the voltage and current generators.

I know that:

$$h_{11}=\frac{V_1}{I_1}\middle|_{V_2=0}$$

$$h_{22}=\frac{I_2}{V_2}\middle|_{I_1=0}$$

$$h_{12}=\frac{V_1}{V_2}\middle|_{I_1=0}$$

$$h_{21}=\frac{I_2}{I_1}\middle|_{V_2=0}$$

I know the general process to solve this problem (e.g. short circuit the terminal when $$V=0$$ or open them when $$I=0$$ etc., but I can't do all the steps to obtain the complete solution.

The solutions are:
Can you please help me explaining to me all the necessary steps to solve this problem and problems like this one? What should I do first, which theorems to use ecc.

Joined Mar 10, 2018
4,057
If you google "example h parameter calculation" lots of
examples on web.

Regards, Dana.

#### MrAl

Joined Jun 17, 2014
7,799
If you google "example h parameter calculation" lots of
examples on web.

Regards, Dana.
Hi,

Then why have this site?
If every answer was "look it up on the web" then this site becomes totally redundant.

Joined Mar 10, 2018
4,057
Help for folks should be broad based. One can argue we provide ALL
assistance, to the limits of supporter knowledge, and one can argue
lead the horse to water, but not drink it for him. Or something in-between.

If supporter has the time to keep re-inventing the wheel I support that person,
as I do the person who points folks to more indepth where a supporter
does not have the time to regurgitate or lacks total knowledge of the
subject. Again a mix......

I often use ref links to material that TS can use in his library, where there
is knowledge of past work that most (I would posit) of us do not want to
re-create.

If every answer was "look it up on the web" then this site becomes totally redundant.
Pretty much agree, but then there is the simple fact that web does not contain all knowledge,
in fact has serious limitations due to things like proprietary data, timeliness of disclosure,
current state of the art.......

In this particular case I was tempted to post a link to the GE Transistor manual as thats
where I learned h parameters 500+ years ago

Regards, Dana.

#### The Electrician

Joined Oct 9, 2007
2,783
I had to do this post over because I missed the line in post #1 identifying the ports.

gianx80, try calculating h11. If you short the voltage source and open the current source, what impedance do you calculate as seen across R1? It's just a simple series/parallel reduction of the circuit.

#### The Electrician

Joined Oct 9, 2007
2,783

The current source at the input is used to find h11 and h21, both of which require the output to be shorted as part of the definition. You connect the current source to the input, disconnect the voltage source at the output and replace it with a short.

The voltage source at the output can be used to find the h12 and h22 parameters which require the input to be open. For these two parameters you connect the voltage source at the output, remove the current source at the input and leave the input open circuited.

#### MrAl

Joined Jun 17, 2014
7,799
Help for folks should be broad based. One can argue we provide ALL
assistance, to the limits of supporter knowledge, and one can argue
lead the horse to water, but not drink it for him. Or something in-between.

If supporter has the time to keep re-inventing the wheel I support that person,
as I do the person who points folks to more indepth where a supporter
does not have the time to regurgitate or lacks total knowledge of the
subject. Again a mix......

I often use ref links to material that TS can use in his library, where there
is knowledge of past work that most (I would posit) of us do not want to
re-create.

Pretty much agree, but then there is the simple fact that web does not contain all knowledge,
in fact has serious limitations due to things like proprietary data, timeliness of disclosure,
current state of the art.......

In this particular case I was tempted to post a link to the GE Transistor manual as thats
where I learned h parameters 500+ years ago

Regards, Dana.
Hi again,

Thanks for the detailed explanation of your point of view.

I guess i have seen people complain that they come to ask a question and then get pushed back to the web when they already did that that's why they ended up here. I suppose though that some may not do that first and so might gain from the experience.
Also, i guess i didnt think the problem was so in depth that it would force us to push to the web. I guess this depends though on what you think is "in depth" or "too complicated".
I can also guess though that some people may not come back as a result of being pushed away. To me the more people that visit the more interesting a site becomes due to the diversity of knowledge.
I see now Electrician is making an effort to help though so maybe the OP will get something out of this.

So in the end not a big problem just something to think about.
I also see people giving specific links which i think isnt too bad of an idea when the subject matter gets more complicated.