Hello, dr.Steven and all meep users
I use meep for a short time and feel that meep is very powerful.
This is also my first poster. I really hope you can help me.
Now I am doing some work about the 2d near-to-far transformation.
But I am confused about two points.
First, I want to use meep to get the near field data.
For a TM wave, I need to get scattered field (Ez, Hx and Hy) in near zone.
So I did the simulation twice. One has the object, one no object. In order to
get the scattered fields, I use the fields (Ez, Hx, Hy) that I got with object
subtract the fields without the object.
In fact, I just need the scattered E and H fields tangential to a virtual
rectangle shape surface completely surrounding the object or scatterer.
Is this right?
Below is my code. Can I take the E and H at the same timestep 300 or I should
take E at timestep 300 and get the average value of H at 299.5 and 300.5?
Second question.
For my ntf code, I set the parameters like this:
Eps0=1
Mu0=1
Z (intrinsic impedance of free space) =1
K=1 (the wave vector of incident wave)
Omiga (angular frequency)=1
Wavelength=a=1 (also a=wavelength)
Wl=40 (resolution)
Then get the tangential E and H and calculate the current Jx, Jy and Mz
Integrate the current
do i=iomin,iomax
!-------the lower boundary ---------
ctemp=cmplx(0.,(float(i)*cos(phi)+(jomin-0.5)*sin(phi))*rk)
ctemp=cexp(ctemp)
mx=mx+mx1(i)*ctemp
jz=jz+jz1(i)*ctemp
…………….
Finally, calculate the electric field in the far zone.
ctemp=cmplx(.0,-rk*r)
ctemp=cexp(ctemp)
Ez(dg)=0.5*(cmplx(.0,k)/(2*pi*r))**.5*ctemp*(-jz*z-mx*sin(phi)+my*cos(phi))
Ez(dg)=cabs(Ez(dg))
………………………………….
Are these parameters right?
Especially for the omiga, for my ntf code I used to set eps0, mu0… as the real
value (8.85e-12…) and omiga=pi/wl, so now how should I set the omiga then it
can match the data from meep?
Is this procedure right?
If it is helpful, I can post my ntf code.
Thanks a lot!
Lei
---------------------------------------------------------------------------------------------------
(set! geometry-lattice (make lattice (size 6 6 no-size)))
(set! eps-averaging? false)
(set-param! force-complex-fields? true)
(define-param pec? true)
(set! geometry
(if pec?
(list (make block (center 0 0 0) (size 2 2 0)
(material (make perfect-metal))))
(list (make block (center 0 0 0) (size 6 6 0) (material air)))))
(set! sources (list
(make source
(src (make continuous-src (wavelength 1) (width 5)))
(component Ez) (size 0 6)
(center -1.9 0))))
(set! pml-layers (list (make pml (thickness 1.0))))
(set! resolution 40)
(run-until 300
(at-end
(to-appended "down" (in-volume (volume (center 0 -1.75 0) (size 3.5
0 0))
output-efield-z output-hfield-x output-hfield-y ))
(to-appended "upper" (in-volume (volume (center 0 1.75 0) (size 3.5
0 0))
output-efield-z output-hfield-x output-hfield-y))
(to-appended "right" (in-volume (volume (center 1.75 0 0) (size 0
3.5 0))
output-efield-z output-hfield-x output-hfield-y))
(to-appended "zero" (in-volume (volume (center -1.8 0 0) (size 0 0
0))
output-efield-z))
(to-appended "left" (in-volume (volume (center -1.75 0 0) (size 0
3.5 0))
output-efield-z output-hfield-x output-hfield-y))))
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