[SOLVED] Move S11 plot on HFSS

[Shika93]

Hi
I'm writing here because I have a problem simulating a Yagi-Uda antenna at 2.4GHz. I parametrized dimensions and distances using lambda and I get a good S11 (-18dB or lower depending on the length and distance of director elements) but is centered around 2.2GHz instead 2.4. I tried using parametric analysis to find good values of length and distance of both reflector and directors, to improve it (which indeed happens) but still around 2.2GHz. How can I fix it?

 

[kthackst]

Well, if you parameterized with respect to lambda, wouldn't that mean you would always have the same resonant frequency? That's generally why antenna engineers like to parameterize with respect to lambda in the first place.

I suggest sweeping lambda until you get the 2.4 GHz response you want, sounds like your design equations are a little off is all. Which is normal for Yagi Uda antennas from my experience.

 

[Shika93]

This is what I thought but in the case of an array like a Yagi with passive elements, to find the resonance it seems to have to play with the distance between each resonator or the distance between the power supply and the resonator or the length of these .
After some attempts I managed to center S11 and have a good radiation pattern without losing the directivity.

I have a question about the convergence. So far it does not converge (6 passes, delta 2e-8, first order solution with fast sweep) but if i add some passes or I improve delta or I use an interpolate sweep, does it change the results? What can I do to make it converge?

 

[fiwi]

You must reduce all antenna dimensions by k = 0.9166

 

[Shika93]

Once I've centered S11 and the radiation pattern is correct?

 

[fiwi]

Once I've centered S11 and the radiation pattern is correct?

,,,no....!!!

 

[Shika93]

Perfect. Worked.
Sorry, but I'm learning this program on my own. Thanks!