Hi, all. I have an urgent problem here. I use HFSS to simulate a 4-port coupler and get the s parameters. I then import that into ADS. I also have drawn the equivalent circuit of this coupler. Then I wish I could use some optimization or fitting method to get the L, C values of this equivalent circuit according to the imported s parameters. However, the material concerning this topic is really limited on the internet. Could anyone help me on this? If you could, please explain as detailed as possible. If a tutorial is available, that might be better. Thank you so much.