insertion loss s parameters

Hi, I have simulated gold plated wires embedded into polyimide material using CST Microwave Studio transient Solver to extract S-parameter (insertion loss) data.

One model is 0.5mm thick and the other is 0.25mm thick. Component geometry in both models is identical except for the thickness.

Interestingly enough, I am getting better S21 (insertion loss) data for the 0.5mm thick model than the 0.25mm thick model @ 20GHz.

I was expecting lower insertion loss for the 0.25mm thick model and higher insertion loss for the 0.5mm thick model (based on wire length).

I would really appreciate if someone could shed some light on the S-parameter insertion loss results.

Cheers,

Does both of the system get same amount of power? That means did you look at the return loss to compare? I guess you can compare the insertion loss if you plot the data using S21/√(1-|S11|)2 for both systems.

I'm not quite sure about the argument, however, it's the case I assume.

regards,
shameemkabir

This look like not simple transmission line.
It look like coupled parallel lines for me so I guess normal plate thickness is one of the parameter.

HI guys, first of all I would like to thank you for your comments. Attached is the S11 plot of both models. Geometry of the models is same except for the wire (length) that connects top plate to the bottom plate per say...

I thought the longer the wire is, the higher the insertion loss will be...may be I am not correct!