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Eigenmode solver confusion

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zam_nmn

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HI

I am trying to design a dual mode sss filter at 1.8GHz and i'm using eigenmode solver to observe its resonance and q value.
I need explaination on the results obtained, why does the resonance are very close to each other?
and how about the q value, is it to high?
 

PlanarMetamaterials

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Hi zam_nmn,

What are you expecting to get? You haven't provided enough information to comment any further. What setup/materials are you using? What are the field profiles of the different mode?
 

zam_nmn

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Hi PlanarMetamaterials,

This is my first time on Eigenmode solver and i don't really know what should i expect from it.
As for my case, i am using suspended stripline in my design with dielectric constant 2.33 and height 0.254mm.
To my knowledge, sss is a purely TEM material where the E and H field are transverse to the direction of propagation. I did set the enclosure as finite cond. so that it can evaluate the losses within.
I have a confusion with the results obtained, why the modes were so close to each other and what actually should i expect for a dual mode sss filter analysis? please guide me as i don't really understand about it.
 

PlanarMetamaterials

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Hi zam_nmn,

I'm afraid I don't know anything about that type of filter. If you post images if the fields though, I can tell you if they are correct for your setup or if there is an error somewhere.
 

zam_nmn

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Hi PlanarMetamaterials,

I am wondering why the resonance frequency and q value will change so much even though i only change the radius for a 0.001 point. let say the previous radius was 14.048mm which resonate somewhere around 1.8GHz with q value of 739. Then i changed the radius into 14.049mm and the resonance and q value greatly changed as per attached photo. i really want to know why this kind of small changes would greatly affect its resonance and q?
 

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I would imagine this is a meshing issue, as you're right, it doesn't seem very plausible. Have you set up a seed mesh in the cavity? To do this, select the cavity and "Assign Mesh Operation". Set the length to be at least 1/20 of the cavity diameter.
 

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