Problems with S21 in HFSS EDT

Hello, I'm Ivan student of University of Valencia.

I'm doing my thesis and I'm having some troubles with ANSYS EDT.

I need to simulate a microstrip of 50 ohms and simulate it with a noise supression sheet to measure the transmission loss. This simulations will be compared with the results that I have obtained with a Network Analyzer.

I'm having problems with S21 and I think it is possible that I don't define correctly the ports.

I attach a PDF file explaining the problems that I'm having and the explaining step by step.

Thank you so much for your help!

Ivan

Welcome IvanUV,

Your magnetic loss tangent varies between positive and negative. Is this an active medium? I believe a negative loss tangent would provide gain, which is what HFSS indicates.

Have you tried simulating the microstrip on its own, without that material?

Thank you for your reply PlanarMetamaterials,

I'm simulating an innovative shielding technique to solve EMI problem, Flexible Absorber Sheets (FAS) which is based on a dielectric-magnetic composite material formed by a polymer.

I attach the specs of the material. I have calculated his magnetic loss tangent like µ''/ µ'.

Regarding to measuring the microstrip without the material, yes I have measured the microstrip its own but I don't achieve good results, it seems like in simulation I measured less dB (for example, with the network analyzer at 3 GHz I have measured around -1dB and simulating I achieve -0.2 dB). I suspect it could be some problems with the lumped ports.

I have attached a report of the process step by step that I use to define my project. I'm a little bite fuzzy because I have tried so many things but I can't achieve the same results.

Thank you for your reply!

Hi IvanUV,

The document you provided gives u'' and u' as both entirely positive. The loss tangent is µ''/µ'. You say you used this equation, but how do you get a negative number out of this?

I would focus first on getting the simulation of the microstrip on its own to match with experiment. Don't try anything more complicated than this before figuring it out, as it's just a waste of your time! How do the S11 and S21 phases compare in this simple case?