Hello I'm having a instability problem which occurs only in the new meep version.I have a source over a metal plate and I want to measure the reflected field. I have a measurement point between the source and the metal plate. If I plot the measured time signal (incident and reflected field), I see that in the beginning everything is okay - I see the incident pulse and a moment later the reflected pulse - , but then after 3000s there is suddenly an huge instability (see attached image). In meep-0.10 I get the same result but without instability after 3000s.
Any idea what is the matter with it? My code is the following: (define-param sx 0.25) ; size of cell in X direction (set-param! resolution 20 ) (define-param sy 60) ; size of cell in Y direction (define-param sz sx) ; size of cell in Z direction (set! geometry-lattice (make lattice (size sx sy sz))) (set-param! eps-averaging? false) (set! force-complex-fields? true)(define-param fcen 0.1) ; pulse center frequency (define-param df 0.8) ; pulse width (in frequency)
(define-param dpml (/ 1 fcen))
(set! geometry
(list (make block (center 0 (- (/ sy 2) 0.2)) (size sx 0.2 sz)
(material (make perfect-metal))))) ;ground plane
(define (my-amp-func p) (exp (* 0+2i pi k (vector3-x p))))
(define-param theta 0)
(define thetaw (*(/ theta 360) 2 pi))
(define-param k (* fcen (sin thetaw)))
(set! k-point (vector3 k 0 0))
(set! sources
(list
(make source
(src (make gaussian-src (frequency fcen) (fwidth df) ))
(component Ez) (center 0 (+ (/ sy -2) dpml))
(size sx 0 sz)
(amp-func my-amp-func ))) )
(set! pml-layers (list (make pml (thickness dpml) (direction Y) (side Low))))
(define R-pt (vector3 0 (- (/ sy 2) 0.3 (/ 3 fcen) ) 0))
(run-sources+ 3500
(at-beginning output-epsilon)
(to-appended "R" (in-volume (volume (center R-pt)
(size 0 0 0 ))
(at-every 1 output-efield-z)))
Regards Cecile
<<attachment: instable_timesignal.png>>
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