Dear Meep users,
I get a frequency shift if I change the resolution.
I'm running a simulation where my meep space unit is a=1cm, hence the
continuous-src is at 6GHz=0.2 in meep units.
I'm saving the points T/0.02 times in a period and I set different resolutions.
If I set the resolution=50 my continuous-src wave is at 6GHz.
If I set the resolution=40, its at 7.49GHz.
If I set it to 60 it becomes 4.99GHz!
(I never change the 0.02)
What's happening? Why do I get this unexpected frequency shift?
this is the way I get my time vector in matlab if sim_p-src.h5 is the
output of meep:
src = hdf5read('sim_p-src.h5','ez');
a=1e-2;
c=299792458;
res=0.02;
t=(1:1:length(src))'*a/c*res;
There is something that I'm missing, hope you can help me
Thanks
Matteo
this is my code:
[QUOTE]
(define-param sxc 40) ; the x size of the computational cell, not including PML
(define-param syc 50) ; the x size of the computational cell, not including PML
(define-param dpml 1) ; thickness of PML layers
(define sx (+ sxc (* 2 dpml))) ; cell size, including PML
(define sy (+ syc (* 2 dpml))) ; cell size, including PML
(set! geometry-lattice (make lattice (size sx no-size no-size)))
(set! default-material (make dielectric (epsilon 100)
(D-conductivity 0.0094)
(mu 1)
))
(set! pml-layers (list (make pml (thickness dpml))))
(set-param! resolution 40) ; resolution parameter
(define-param fcen 0.2) ; pulse center frequency
(define-param df 0.1) ; turn-on bandwidth
(set! sources
(list
(make source
(src (make continuous-src (frequency fcen) (fwidth df)))
(component Ez) (center -19 0)
)
)
)
(define-param T 300) ; run time
(run-until T
(at-end output-efield-z)
(to-appended "src" (at-every 0.02 (in-point (vector3 -19)
output-efield-z)))
(to-appended "tgt-1" (at-every 0.02 (in-point (vector3 -14)
output-efield-z)))
(to-appended "tgt-2" (at-every 0.02 (in-point (vector3 -9)
output-efield-z)))
)
[\QUOTE]
--
Matteo Bassi, PhD Student
Department of Information Engineering
University of Padova
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