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Simulating metamaterial in HFSS

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achiravuri

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Hello everyone,

I'm trying to simulate a unit cell of a volumetric transmission line in HFSS, like Figure 1 in the paper. My question is, how did they graph the propagation constant vs frequency. I've looked through HFSS manuals and can't find it. Any help would be appreciated.
 

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  • Ivestigations on volumetric layered transmission line metamaterials for antenna applications.pdf
    2.3 MB · Views: 318

You need to write the expression for Phase contant (beta). Create an output variable with the expression for the phase constant. Let me know if you are not able to do.
 

I found an expression of the phase constant in this paper, on page 20. Beta = acos((1-S11*S21+S12*S21)/(2*S21)). Is this correct or, do I need to use something else? Also, I was told that when the real part of Beta goes negative, that's when the structure is acting as a metamaterial, is that true?
 

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  • Disperse Diagram.pdf
    1.8 MB · Views: 339

You can use that expression for beta = acos((1-S11*S21+S12*S21)/(2*S21))
 

ok, so for the past week and a half, i've been running different simulations, but my beta never touches zero. i've attached my simulation and its result, please let me know if there are any problems with it
 

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  • 2x1.zip
    110.8 KB · Views: 213

you set your solution frequency wrong. you sould set it to 10 GHz (highest frequency)
 

wave85 said:
you set your solution frequency wrong. you sould set it to 10 GHz (highest frequency)
Click to expand...


Thanks for pointing that out. I've got another question for you, how am I supposed to design the air box? I noticed my results change dramatically if i change the dimensions of the air box.

thanks
 

the size of your radiation box should be at least 10 times of longest wavelength.
when you get different result with different radiation box, it means your radiation box isn't enough big.
Good luck
 

how can you set the frequency in HFSS?do i have to set the boundary conditions i meant pec and pmc on the edges. how the electric and magnetic field play their roles here? can anybody explain? thanks

---------- Post added at 19:42 ---------- Previous post was at 19:35 ----------

how can you set the frequency in HFSS?--i know this now..but please get back to me with the other questions?
 

hi,

Can anybody please clarify this...i have got this from the smith srr+wire hfss file

mag(S21)*(cos(-ang_deg(S21)) + cmplx(0, 1)*sin(-ang_deg(S21)))
mag(S11)*(cos(-ang_deg(S11)) + cmplx(0, 1)*sin(-ang_deg(S11)))

I have read smith paper but don't know where this equation comes from?

I will appreciate if anybody can please get back to me urgently...
 

hi,

i am having the same problem. can anybody please get back to me on the following:
mag(S21)*(cos(-ang_deg(S21)) + cmplx(0, 1)*sin(-ang_deg(S21)))
mag(S11)*(cos(-ang_deg(S11)) + cmplx(0, 1)*sin(-ang_deg(S11)))

Hope to hear from any of you very soon.

thanks
 

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