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Simulators >> System Simulators >> Channel S-Parameters in Simulink
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Message started by .matteo on Jun 27^th, 2009, 12:48pm

Title: Channel S-Parameters in Simulink
Post by .matteo on Jun 27^th, 2009, 12:48pm

Hi everybody,
I created a communication system to simulate a ranging system. After some measurements I collected the S-Parameters of the channel in a s2p file and I would like to through these parameters into the model of my channel for a more precise simulation.

How can I do it? Does anybody have previous experiences to share about it? I have the RF Toolbox too

Thanks

Title: Re: Channel S-Parameters in Simulink
Post by pancho_hideboo on Jun 27^th, 2009, 1:42pm

.matteo wrote on Jun 27^th, 2009, 12:48pm:

How can I do it? Does anybody have previous experiences to share about it? I have the RF Toolbox too

"RF Toolbox" is MATLAB not Simulink.
MATLAB are different from Simulink.
See documents of "RF Blockset" of Simulink.

If you have "RF Blockset", you can use s2p file easily.
Use the following three blocks.
RF Blockset>Physical>Input/Output Ports>Input Port
RF Blockset>Physical>Input/Output Ports>Output Port
RF Blockset>Physical>Black Box Elements>General Passive Network

Of course, here you have to understand concept of equivalent lowpass model for RF bandpass system very correctly to use these blocks.

If you don't have "RF Blockset", create complex coefficients FIR model to express S21 as equivalent lowpass model.
Of course, also here you have to understand concept of equivalent lowpass model for RF bandpass system very correctly.

You have to understand that models of Simulink are no more than signal flow system not energy conservative system which have flow and potential, although "RF Blockset" take account of S11, S12 and S22.

Title: Re: Channel S-Parameters in Simulink
Post by .matteo on Jul 1^st, 2009, 9:22am

I did it and it works great.

My only concern is about the input and output impedance of the equivalent S-parameters RF model in Simulink.

The data was acquired with a network analizer and it's just the s-parameters of the free space path given by two antennas ..I think I should set 0 input impedance and infinite output impedance in simulink. Do you agree?

Title: Re: Channel S-Parameters in Simulink
Post by pancho_hideboo on Jul 1^st, 2009, 9:46am

.matteo wrote on Jul 1^st, 2009, 9:22am:

The data was acquired with a network analizer and it's just the s-parameters of the free space path given by two antennas ..
I think I should set 0 input impedance and infinite output impedance in simulink.
Do you agree?

Not correct.
It seems you don't understand S-parameter you measured at all.

Your S-parameter is for ANT-Space-ANT.
Your concern is S21, so input and output must be terminated by 50ohm.