Dear Meep Users, In the past month of trying to learn meep, I have benefited greatly from these discussions. So before my ramble I would like to thank everyone for reading this. I am truly grateful for your help.
I am trying to calculate the effective parameters (namely the permeability and permittivity) of the structure I am simulating. To do so, I must find the transmission and reflection coefficients, which to my understanding can be found by simply outputting the electric field components twice (with and without the structure) and taking a ratio after performing fft on the electric field components. Reflection coefficients = fft(R-R0)/fft(T0) Transmission coefficients = fft(T)/fft(T0) This method has been described previously, https://www.mail-archive.com/meep-discuss%40ab-initio.mit.edu/msg04262.html https://www.mail-archive.com/meep-discuss%40ab-initio.mit.edu/msg00849.html The problem I am having is that when I perform a sanity check on the coefficients I arrive at, by taking the absolute value squared of the reflection and transmission coefficients, I get values that do not make sense, and do not match the (power) Reflection and Transmission values that I get when I perform the simulation. To provide additional information about the structure I am simulating, it is a column of gold split ring resonators (periodic in the y direction). I included PML in the X direction only. [R] l C l l [S] C [T] l l C l l l C l l l C l l l C l [R]-Reflection line [S]-Source line [T]-Transmission line Here is a snippet of my code, I omitted parts that are unimportant. (set! ensure-periodicity true) (set! k-point (vector3 0 0 0)) (set! eps-averaging? false) (set! force-complex-fields? true) (define-param no-grating? false); if true, then use control (set! geometry-lattice (make lattice (size sx sy no-size))) (set! geometry (if no-grating? (list ) (list (make cylinder (center 0 0) (radius outradius) (height infinity) (material gold)) (make cylinder (center 0 0) (radius inradius) (height infinity) (material air)) (make block (center 0.83 0) (size cube cube infinity) (material air)) ))) (set! pml-layers (list (make pml (direction X) (thickness 1.0)))) (set! sources (list (make source (src (make gaussian-src (frequency fcen) (fwidth df))) (component Hz) (center -2.4 0 0) (size 0 sy)))) (run-until 560 (at-beginning output-epsilon) (in-volume (volume (center 2.9 0 0) (size 0 sy 0)) (to-appended "T" (at-every 1 output-efield-y)))) Thank you all very much for your time. Joshua Surya Electrical and Computer Engineering University of Illinois Urbana-Champaign | B.S. Class of 2015
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