Hello MEEP users,
I am facing problem with Harminv Function.
In my code I am simulating a TM111 mode in cylindrical
resonator(r=10mm, h=20mm) for which the eigen-frequency is 19.44 GHz.
But Harminv is giving a frequency of 18.85GHz. Setting a sharp width is
also not helping.
Moreover I have simulated TE011 mode which is degenerate with TM111.
For this I have used the same code but changed source as Hz and position
as (0 0 0) and I am getting a very good result too.
Here's my code:
(reset-meep)
(define-param ra 10)
(define-param ha 20)
(define-param rm 12)
(define-param hm 24)
(set! geometry-lattice (make lattice (size (+ rm rm 4) (+ rm rm 4) (+
hm 4))))
(set! geometry (list
(make cylinder(center 0 0 0)(axis (vector3 0 0 1))(height hm)(radius
rm)(material metal))
(make cylinder(center 0 0 0)(axis (vector3 0 0 1))(height ha)(radius
ra)(material air))
))
(set-param! resolution 3)
(define-param fcen 0.0648)
(define-param df 0.01)
(set! sources(list
(make source(src (make gaussian-src (frequency fcen) (fwidth
df)))
(center 4.89 0 7)(size 0 0
0)(component Ez))
))
(init-fields)
(define (f_e r ex ey ez)
(sqrt (+ (* ex ex) (* ey ey) (* ez ez)))
)
(output-field-function "electric-function" (list Ex Ey Ez) f_e)
(define (electric-output) (output-field-function "electric-function"
(list Ex Ey Ez) f_e))
(define (f_m r hx hy hz)
(sqrt (+ (* hx hx) (* hy hy) (* hz hz)))
)
(output-field-function "magnetic-function" (list Hx Hy Hz) f_m)
(define (magnetic-output) (output-field-function "magnetic-function"
(list Hx Hy Hz) f_m))
(run-sources+ 200 (at-beginning output-epsilon)(after-sources (harminv
Ez (vector3 5 5 5) fcen df)(at-end electric-output)(at-end
magnetic-output)))
(define freq (car (map harminv-freq-re harminv-results)))
(print "frequency:" (* 299.79245 freq) "GHz\n")
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