Need help with Vivaldi antenna in hfss simulation

I am asking for help.

I have made a vivaldi antenna simulation in HFSS v12.0.1

But I have troubles with waveport, and because of this very bad VSWR, S11, real and im impedance parameters...

How should I change my waveport to get normal parameters?

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Model of my Vivaldi antenna to download: ww w.edaboard.com/attachment.php?attachmentid=51216&stc=1&d=12912197 94


S11 plot: ww w.edaboard.com/attachment.php?attachmentid=51217&stc=1&d=12912198 31
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P.S. sorry for my english and not normal links, I can't post links until reach 2 posts...

When you are defining waveports, renormalize the impedance of the waveport. So the impedance is equal to the characteristic impedance of 50 ohm.

Renormalizing changed all characteristics, but not solved the problem.

I will clarify requirements for antenna:
1) stable characteristics on range 3-11 GHz
2) re impedance = ~50 Ohm; im impedance = ~0 Ohm;
3) stable VSWR less then 10 in dB

Below file with my antenna and screens of VSWR, impedances, antenna with port.

And the question: what can be wrong with model, and what should I review and change?..

Hey your line in one of teh taper top one is not touching the ground ..it should touch there so as to form proper microstrip line feed..try that and let me know if it helps ...then we will discuss further

Hi,

I have corrected your model. See the attached file. This is not vivaldi antenna,it is antipodal vivaldi antenna. you dont need waveport to excite it,instead you need lumped port so that microstrip to feedline transition works properly. As you can see in the VSWR and S11 graph,model is working from 5Ghz to onwards. I havnt optimized the groundplane taper as i do not have time.To enhance bandwidth and go down in freuqency as you mentioned in your previous post play with Groundplane tapering and you will easily get good VSWR which ll cover your required bandwidth i.e 3-11GHz! if you have any questions feel free to ask.

/SC

Thanks for answers. Its useful.

But now, I'm not working on it already.