Convert an antenna project from Ansoft Designer 1.1 to HFSS9
I'm studying very deeply the Ansoft Software. I have realized a project for a microwave antenna using Ansoft Designer, this antenna works very fine in the 4.4GHz-5GHz frequency range. The S11 is always under -10dB, in his frequency range. I'm trying to simulate the same antenna using HFSS, but it seems much more difficult, i tried to use the same ideas used for the designer project. In designer i've always used copper for the conductors with 0 thickness, to project the antenna. To do the same on HFSS, i have realized 2D areas and i've extensively used the Finite Conductivity(use copper conductivity) as boundary condition for the copper used for microstrip and the other metalizations.
After that i have surrounded the project using a lambda/10 thick airbox (6mm) and a lambda/20 PML on it. This is completed using a Lumped port placed on a double stub (exactly as the Port present on the original designer project). I've tryied to vary the airbox and pml thickness to obtain a wider frequency range where S11<-10dB but actually the best is 4.18GHz-4.4GHz with 6mm for AirBox and 3mm for PML.
I think that i can simulate better the antenna on HFSS, but i'd like some suggestion. On designer the ground area where H-shaped slot is present is an infinite ground plane, i can't do the same on HFSS because the Infinite Ground plane is available ONLY if the plane is used as backgound (no other structure should be placed in the back!!).
I ask you a sincere help to get some better result.
I share the original Designer project for the antenna(no modifications are necessary) and the HFSS project(suggestions are greatly appreciated).
My task is to project the same antenna, realized in Designer ,using HFSS and try to obtain a similar performance.
With sincere appreciation
PS.In the HFSS project i use a wider frequency (4-5.4GHz) sweep because, usually, there is a small frequency shift between the Designer and HFSS results
S.
The distance between PML and DUT is not large enough, I guess.
Please try at least lamda/4 spacing.
Have you tried with Radiation boundary condition?
It seems there is no difference between them.
Hello mild-seven, before all, thank you very much for your interesting suggestion.
I've tryied to use lambda/4 thickness for airbox and lambda/20 for PML(as in my project) this variation, for airbox, gives better result.
Then i've tryied using an airbox thickness of lambda/2(30mm) and PML thickness of lambda/20(mm), this variation gives the best result.
I post the result on 2 images, in the first you can see the original result (my goal is to obtain,using HFSS, the best matching between the HFSS and Designer Projects) using the Designer Project. In the second image you can see the difference between the default value for the Minimum Radiating Distance Parameter and my personal best usual value.
I'd like to know much more about this parameter, i don't understand the real importance of the "minimum radiating distance" parameter.
I hope to get another wonderful suggestion.
With sincere appreciation
S.
That's the second image fo the HFSS result and some considerations.
Hi TheSirac :
The distance is not my personal idea.
For past HFSS7 or 8, they feature the PML function.
And I remember Ansoft suggests lamda / 4 for the PML distance setting.
The process is much more simple, compared with HFSS9.
Try to ask someone else who had the experience on old HFSS 8.
Thanks Mild-Seven, please can you give a link to get some information about the PML assigning process in HFSSv8 and some about Minimum Radiating Distance parameter?Please
Sincerely 8)