Discussion Forum

Hello,

I am doing simulations with RF module. It is about the plasmonic resonance in MIM structures.

Actually I would like to use more than one active input ports in my structure. However, when using more than one input port, COMSOL will not provide the S-matrix components in the post-computation list. Hence, I need to figure out a way in order to calculate the S-parameters using mathematical operations.

From the RF user guide manual, the S11, S21, and S31 can be calculated using the following equations (attached below).

So after simulation (parametric sweep on wavelength) is done I have the computed magnitude of electric field which is in COMSOL "emw.normE".

Then according to the equations in COMSOL RF user guide in order to calculate S11, I need first to subtract the magnitude of the computed field from the magnitude of the incident electric field to get the magnitude of the reflected. For the incident field in my simulations I used "in plane" electric field excitation so I have Ex = 1V/m and Ey = 1V/m. Therefore I subtract emw.normE from sqrt(2) (magnitude of the incident electric field).

This is the equation I used to calculate S11 and should be consistent to that reported in COMSOL RF userguide:
S11 = line_integration_along_the_input_port_length( (emw.normE-sqrt(2))*sqrt(2)) / 2

The results (attached below) for the S11 calculated by equation is not similar to that obtained by COMSOL in the post-processing list (attached below).

So my question is how to calculate the S11 parameters using the line integration on COMSOL 5?

Waiting sincerely for your help.

Best regards,
Hassan