Learning Forum

[rnjstjrrn98]

hello, I have a question when simulating in FDTD.

I do research on absorption tailored to the frequency of a specific band with metamaterials. 
When simulating, a dielectric constant suitable for that frequency was used, but the absorption rate was rather low at that frequency.At other target frequency, the absorption rate is high. Why is that?

[Guilin Sun]

Without details about the structure/materials and settings I can only say that, for engineered material such thing can happen, since there might be some resonance or other physics that lead to such results. I would suggest you to check the if the structure and simulation settings are correct. for example periodic conditions and plane wave source should be used. Is the reflection/transmission normal?

 

[rnjstjrrn98]

This metamaterial is designed to absorb two frequencies in different bands via surface plasmon resonance.
As far as I know, the dielectric constant of the dielectric varies with frequency.
The simulation was conducted by substituting a dielectric constant suitable for one of the two frequencies mentioned earlier, and the absorption rate at this frequency is lower than that obtained through actual manufacturing and experiments.

 

According to actual experiments, the right pick should come down to 0.1 level.

 

I wonder why these results are happening in simulations.

[Guilin Sun]

Not sure if the above plot is absoprtion, or reflection/transmission. If you plot all of them in the same graph you will know where the power goes.

A=1-R-T