Finding h parameters when capacitors and inductors involved with resistors

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Discussion Overview

The discussion revolves around finding the h parameters of a circuit involving inductors, capacitors, and resistors. Participants explore the implications of these parameters in both AC and DC contexts, as well as the significance of component values expressed in ohms without specifying frequency.

Discussion Character

  • Homework-related
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant requests a detailed manual solution for finding h parameters, expressing confusion about the significance of component values in ohms without a specified frequency.
  • Another participant outlines the formal procedure for calculating h parameters, emphasizing the need for the original poster to work through the problem independently.
  • A participant questions whether h parameters can vary with time, suggesting that sinusoidal inputs would lead to non-constant currents and ratios, while DC inputs would stabilize the circuit to behave like a resistor circuit.
  • Another participant asserts that h parameters are not time-variant and are defined by constant component values, indicating that two-port networks are typically restricted to AC signals.
  • One participant suggests rewriting the two-port equations in terms of different parameter sets (z and y parameters) to avoid potential singularities in the h parameter equations.

Areas of Agreement / Disagreement

Participants express differing views on whether h parameters can vary with time, with some asserting they are constant under certain conditions while others argue that they may change with AC signals. The discussion remains unresolved regarding the implications of using AC versus DC sources.

Contextual Notes

Participants highlight the importance of understanding the conditions under which h parameters are defined and the potential for singularities in calculations, indicating that assumptions about circuit behavior may depend on the type of input signal used.

sns
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Homework Statement



Find the h parameters of the following systems:-

---L---------C--
:
:
R
:
:
----------------​

L= j5 ohm
C=-j5 ohm
R=1 ohm

Homework Equations



The above questions has to be solved manually as well as simulated (Matlab-simulink).
If anybody can please give a detailed solution explaining all the steps used I will be very grateful.
I only need the manual solution then obviously I can simulate the circuit. Also please explain the significance of giving L and C in ohms without specifying the frequency of supply to be used. Is this circuit only for an a.c. source? Can h parameters vary with time?

Thanks.
 
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Well, first write the h-parameters equations:

V1 = h11*I1 + h12*V2
I2 = h12*I1 + h22*V2

And to find the parameters follow the formal procedure:

First, by shorting V2 (that is, making V2 = 0), you can find:
h11 = V1/I1
h12 = I2/I1

Then, by opening the first port (that is, making I1 = 0), you can find:
h12 = V1/V2
h22 = I2/V2

And then after writing the equations, things going to be clear to you. Of course, I would like to help and solve all the project for you, but this isn't how it supposed to be. You have to work out the rest by yourself :biggrin:
 
Su3liminal said:
Well, first write the h-parameters equations:

V1 = h11*I1 + h12*V2
I2 = h12*I1 + h22*V2

And to find the parameters follow the formal procedure:

First, by shorting V2 (that is, making V2 = 0), you can find:
h11 = V1/I1
h12 = I2/I1

Then, by opening the first port (that is, making I1 = 0), you can find:
h12 = V1/V2
h22 = I2/V2

And then after writing the equations, things going to be clear to you. Of course, I would like to help and solve all the project for you, but this isn't how it supposed to be. You have to work out the rest by yourself :biggrin:

Well I had done the same and when I do it I start getting the same problems all over again.. Firstly please clear my concepts:
Can h parameters vary with time? Because if we supply voltage V1 ie sinusoidal then currents flowing will not be constant.. thus ratios wouldn't be constant.. Am I correct? Thus will h-parameter be an equation eh?
But if supply d.c. voltage and wait for circuit to be stable... then capacitor ultimately blocks current and inductor just passes current through.. then definitely h-parameters are constant. It'll just be a resistor circuit finally? Is this evaluation correct?

Please help..
 
sns said:
Well I had done the same and when I do it I start getting the same problems all over again.. Firstly please clear my concepts:
Can h parameters vary with time? Because if we supply voltage V1 ie sinusoidal then currents flowing will not be constant.. thus ratios wouldn't be constant.. Am I correct? Thus will h-parameter be an equation eh?
But if supply d.c. voltage and wait for circuit to be stable... then capacitor ultimately blocks current and inductor just passes current through.. then definitely h-parameters are constant. It'll just be a resistor circuit finally? Is this evaluation correct?

Please help..

1. Your h parameters are not time-variant. They are defined solely by your component values, which are presumably constant. Almost by definition, 2-ports are restricted to ac signals.

2. I'm not going to try to solve the h parameter equations as suggested by su3liminal. That's because they may lead to singularities (& I'm too lazy to find out). In which case what you need to do is rewrite the 2-port equations in terms of a different parameter set. Try the z and the y parameters. Then get a table that gives you the h parameters given the z or y parameters.
 

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