help with CST graphs of the eigen solver

[monx]

cst eigen solver

i am simulating periodic structures with the CST. I am using the eigen solver to get one graph with phase vs frequency. it is suppose that there is one relation between the phase 0-360 degrees with the parameters Γ, M, X.
can somebody explain me how i can related these parameters with the phase and what this parameters mean???
thanks for your help

 

[doug freeman]

I'm assuming you're looking at a pbg or similar.

In this case you need to keep one phase shift to zero and sweep the other to 180. Then keeping this at 180 sweep the other from 0 to 180. Then sweep the first one 0 to 180 while keeping the second one at 180. You must reverse the last graph though as in reality you are going from 180 down to 0 but CST won't let you do this.

Now you have 3 graphs of the mode frequency v phase, put them all togther to get the irredducible zone babd graph.

Added after 1 minutes:

This might help;

**broken link removed**

it's for HFSS but the method is the same

 

[monx]

you are right, i am simulating a pbg structure.
now i will try to simulate as you say, but still I don't know what these regions (Γ-X, X-M and M-Γ) are and which relation they have with the phases.
I have found that:
-> Γ-X represents βxa/π when βy=0, so maybe this is the first simulation that you told me (Xphase=0)
-> X-M represents the region of βya/π when βx=π/a;maybe this is the second simulation (Yphase=180)
-> M-Γ represents βxa/π when βx=βy; and maybe this is the last (Xphase=180)

I am not sure if this is the relation between what you told me in the previous e-mail and these regions, and I don't know which is the meaning of these letters. If you can clarify me these things will be great.

Thanks so much for your help



I didn't realize that you had sent me a link where is explained, now I am reading it, and it seems to be more clear. thanks for you help.

 

[asjade]

I am afraide that CST eigen solver can't solve eigen mode problem with open boundary like PML. The 2.5D problem like mushroom PBG setup PML boundary in the top face of cellular unit. So the system is open. Can CST solves this kind of system?

 

[vtrs]

Well the method doug freeman suggested is generally right. I only disagree with the third M --> Γ phase shift. While both phase shifts are at 180deg at M point, in order to get back to the Γ point you should sweep both phase shifts from 180deg to 0deg. Be also ware that these values of phase shift correspond to the square lattice. The triangular lattice can't be solved with CST-MWS 5. I don't know if with CST 2006 the problem has been solved . Good Luck

 

[asjade]

You can't solve any lattice other than square directly with periodic boundary applied on the unit surface. But you may use mulriple lattice to meet square boundary condition. If you use HFSS,you can assign any face inside your system periodic condition, so any kind lattice you design can can be solved easily.