Discussion Forum

Hello, I am simulating a plane EM waves (TE) propagating through free space that is incident at an angle upon an infinite dielectric medium (e.g. air to glass), using the model given in www.comsol.com/model/fresnel-equations-12407.

I was able to compute the reflectance, abs(emw.S11)^2 and transmittance, abs(emw.S21)^2, both of which agree well to the analytic expression (e.g., refer to Equation (5) and (6) in the model for the Fresnel problem in TE case). I have attached my simulation for your inspection.

Now, my problem is to extract the phase of the reflected electric field at the port boundary, which is pi in our case.

However, when I attempt to extract the phase from the computed emw.S11, by typing arg(emw.S11), it seems unreasonable, I find that emw.S11 does not match to the analytic reflection coefficient, which you can find in the 1D plot in my file.

I have two questions. First, I am puzzled at the moment to understand the difference between the analytic expression of the reflection coefficient (e.g., Equation (2) in www.comsol.com/model/fresnel-equations-12407) and the computed emw.S11.

Second, will you please advise me how to formulate emw.S11 to match the analytic reflection coefficient, (Equation (2) in the above link)? It appears that abs(emw.S11)^2 is equal to the analytic reflection coefficient squared, (r_s)^2, however, I am not sure how to extract the analytic reflection coefficient from the simulation.

I appreciate your time.