finding s parameters for low pass filter

Hi guys I have a microstrip low pass filter with all the dimentions , I need to find the s11 parameter can someone point me in the right direction, please? A website, example, e book, anything please? the diagram is below, Thank you


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The best would be to use a Network Analyzer to do the measurements.
If you know the properties of the Substrate Material (Er, Thickness, Loss, etc.) you can use softwares as MWO, Eagleware, ADS, Ansoft etc, to simulate the filters and find the impedances.

I need to calculate directly using formulas and figures etc. its t osee if I am able to do it with out equipment.

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