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HFSS Eigenmode and Wavenumber

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JohnFid

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Hello, I am trying to implement a periodic cell for antenna design and I want to produce a diagram Frequency Vs Wavenumber in eigenmode. How can I import wavenumber to my design? As I know, HFSS use ko, wavenumber in free space of each mode to calculate resonation frequency. Thank you.
 

I assume by wave number (k), which is effectively constant, you mean the phase "constant" β.

This can be achieved by implementing a variable angle into the master/slave boundaries of your eigenmode simulation, where this Angle = β*d, where d is the length of your cell. I've written instructions on this forum before - check out https://www.edaboard.com/threads/265560/#post1140645

Good Luck
 
Kx=bx-jax according to the paper...and kx is from 0 to 1800..What exactly value do i have to put on the delay? it must be multiple to 180 or 360? ax is attenuation constant and bx phase constant
 

JohnFid said:
Kx=bx-jax according to the paper
Click to expand...

Called the propagation constant where I come from, but I get what you're saying.

What exactly value do i have to put on the delay?
Click to expand...

The delay is a phase delay, I.E. and angle. It repeats itself every 180 degrees, so you want to sweep 0-180
 
PlanarMetamaterials said:
The delay is a phase delay, I.E. and angle. It repeats itself every 180 degrees, so you want to sweep 0-180
Click to expand...
But how I get the diagram for kx = 0:1800?
This is the project:
View attachment cell2.zip
and this is what I trying to produce:
Untitled.jpg
If you have time please take a look..
 
Last edited:

Hi John,

I understand now, it's k_x, not k*x. This is just the phase constant (β) to which I was referring - so what you need to do is take my equation Angle = β*d, and get β = Angle/d.

This is the tricky part - it doesn't give units for k. It could be rad/m or degrees/m. It appears to be radians, from the graph title, so you would sweep from 0 degrees to

Angle = 1800*(pi/180)*(d)

However, to be thorough, you should really just sweep 0 - 180 degrees. This might be the same case if your unit cell is the proper size, however.
 
First of all, thank you for your immediate answer.
If I understand, I will create a variable k_x which will vary from 0 to 1800 (sweep) and the phase delay will be Angle = k_x * (pi/180) * d?
I tried sweeping from 0 to 180 deg but the results wasn't the same.. :(
 

If I understand, I will create a variable k_x which will vary from 0 to 1800 (sweep) and the phase delay will be Angle = k_x * (pi/180) * d?
Click to expand...

Yes, I believe that is correct.

I'm sorry that your results didn't turn out. Sweeping 0-180 should give you all the information there is to obtain. However, there are numerous simulation settings to account for. You may want to check:

Minimum Frequency
Number of Modes
Convergance (Δf)
$Angle Step Size

Good Luck
 
Thank you very much, PlanarMetamaterials. I had some erorrs on my design but I fixed them. It seems to work now.
The results are very similar to that on paper. :)
 
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