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Plane wave excitation in CST

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Toshak

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could not set up plane wave excitation due to

How realize a plane wawe excitation of infinite dielectric half-space with a uniform plane wave in CST MWS? Such example have described on CST website (https://www.cst.com/Content/Applications/Article/Article.aspx?id=355) but I can't realize it myself. The main goal consist in excitation of infinite dielectric (glass) half-space with plane wave from infinite vacuum half-space. Then I create such structure (vacuum-dielectric) with a periodic boundaries in all directions except Zmin and Zmax (where I set up open boundaries) and use frequensy solver, CST MWS writes "Could not set up plane wave excitation due to inhomogeneous materials on the plane wave boundares". If set up Zmax or Z min to "open add space" calculation gives reflection wave from background material. This is undesirable for analyse.
Thanks.
 

Hi
I am also having a hard time triying to get those results. Did yo get to figure it out?
 
Yes. I have some success in this domain. The main part of this simulation is using waveguide port as excitation signal. If the waveguide port define on the periodic boundary conditions then the first and the second modes are the plane waves with the perpendicular polarization. So the program looks followed. Open boundary conditions at the directions of propagation of plane wave (Zmin and Zmax in simple case) and periodic boundary conditions at othe directions (Xmin, Xmax, Ymin, Ymax). Waveguide port as excitation signal (the normal of the port nx=0,ny=0,nz=1 if it define on the Zmin). Use frequency solver with desirable monitors.
Asking another if some problems appear.:)
 
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    nasr

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Hi Toshak,

I'm facing the same problem with CST 2010 but defining waveguide port is a little useless as it will be ignored automatically during simulation if you defined open boundaries at top and bottom of your sample as this adds floquet ports at top and bottom of the structure with unit cell B.C. around the object so why should we still put a waveguide port?
 

I mean here that there must be some other way to add ports which excite this sample...these ports should be able to capture S11 (or let's say reflection) from this half-space dielectric...in my case it is multilayered...does anyone here know how to do that?
 

Hi!
I have been able to do such simulations. More specifically, I tried (1) a two-phase system comprising half-space vacuum and half-space lossless silicon (epsilon=11.9 and mu=1) and (2) a three-phase system comprising vacuum, thin film of arbitrary material (I tried epsilon=2, mu=1 and a dispersive epsilon corresponding to gold in the visible with mu=1) and a semi-infinite substrate made of lossless silicon.

I did this using unit cell boundary conditions for x and y directions with open boundaries and Floquet boundary conditions with exiting the lowest two modes (corresponding to s- and p-polarized waves). This worked for all angles of incidence and I got both the s- and p- reflection coefficients correct (both the amplitude and phase). However, I am having trouble comparing the Fresnel transmission coefficients with SZmin,Zmax (the S-parameter) because I can't find how the latter is defined in CST.

Therefore, this setup seems to work in absence of diffraction. Not sure it will work in cases where the interface is not perfectly flat and higher order diffraction modes appear...

Has anyone else been working on plane wave scattering on periodic structures using CST?
 

goran1901 said:
Hi!
I have been able to do such simulations. More specifically, I tried (1) a two-phase system comprising half-space vacuum and half-space lossless silicon (epsilon=11.9 and mu=1) and (2) a three-phase system comprising vacuum, thin film of arbitrary material (I tried epsilon=2, mu=1 and a dispersive epsilon corresponding to gold in the visible with mu=1) and a semi-infinite substrate made of lossless silicon.

I did this using unit cell boundary conditions for x and y directions with open boundaries and Floquet boundary conditions with exiting the lowest two modes (corresponding to s- and p-polarized waves). This worked for all angles of incidence and I got both the s- and p- reflection coefficients correct (both the amplitude and phase). However, I am having trouble comparing the Fresnel transmission coefficients with SZmin,Zmax (the S-parameter) because I can't find how the latter is defined in CST.

Therefore, this setup seems to work in absence of diffraction. Not sure it will work in cases where the interface is not perfectly flat and higher order diffraction modes appear...

Has anyone else been working on plane wave scattering on periodic structures using CST?
Click to expand...

Hi, can you put you upload your project file here, as I am also working in this direction, but couldn't find solution for reflection coefficient VS angle of incidence for two layer (glass/Air) system and for trilayer system(glass/gold/Air). I used unit cell boundary conditions along x and y direction and PML with floquet ports along z direction. I get two ports i.e., Zmin and Zmax, I excite Zmin port, I get an error after critical angle "The material in port Zmax corresponds to a scan angle outside the visible space. Please change the background material to the material with the lowest product of relative permeability and relative permittivity (the lowest refraction index), or use periodic boundaries with the phase specified rather than the scan angle."

If you have done this problem then, please explain me in detail, how you did this and It would be great, if you post your project file.

Thanks,
 
Hi.
I never used critical angle. It's interesting to try) Now I use plane wave instead of ports and Transient solver. Could you upload your project? I'll try to run it.
 

aleem_jamali said:
Hi, can you put you upload your project file here, as I am also working in this direction, but couldn't find solution for reflection coefficient VS angle of incidence for two layer (glass/Air) system and for trilayer system(glass/gold/Air). I used unit cell boundary conditions along x and y direction and PML with floquet ports along z direction. I get two ports i.e., Zmin and Zmax, I excite Zmin port, I get an error after critical angle "The material in port Zmax corresponds to a scan angle outside the visible space. Please change the background material to the material with the lowest product of relative permeability and relative permittivity (the lowest refraction index), or use periodic boundaries with the phase specified rather than the scan angle."

If you have done this problem then, please explain me in detail, how you did this and It would be great, if you post your project file.

Thanks,
Click to expand...

Hi aleem_jamali!

I suggest you to try to do ask the program said: instead of specifying the scan angle - state the phase difference from one face to the other. I guess the problem is that CST calculates angles relative to the background material which is obviously not air in your case. Or simply set air as background and see what happens.

Regards,
goran1901
 

Toshak said:
Hi.
I never used critical angle. It's interesting to try) Now I use plane wave instead of ports and Transient solver. Could you upload your project? I'll try to run it.
Click to expand...

Dear Toshak, did you able to simulate plane wave application in frequency solver? could you please upload it? i have hard time to do this
thank you
 

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