HFSS - [error] Could not preserve critical nodes.

Does anyone know what causes the error message from HFSS

"[error] Could not preserve critical nodes." ?

I got this when trying to simulate a thin dipole (length 500 mm, radius 0.000001 mm) at 299.792458 MHz, which is a frequency at which the dipole should be exactly \[\lambda\]/2 and so have an input impedance of 73 + j 42 Ohms.

Does anyone know how I can simulate a thin dipole in HFSS and get the textbook result?

Deborah.

Hi Debora

Could you upload the actual file,the file thats zipped is an auto file not .HFSS.

Regards
Sajid Mohammed.

rotmanlens said:

Hi Debora

Could you upload the actual file,the file thats zipped is an auto file not .HFSS.

Regards
Sajid Mohammed.

Click to expand...

Oops, lets try again. I don't know how to remove the first one, but I'll try to attach the correct file this time.

Unfortunately Deborah i am having a hard time seeing your dipoles.even when zoomed in to the max. what are we racing towards to simulate infinetly thin dipole ever .

will check the values and let you know

Regards
Sajid Mohammed.

---------- Post added at 20:47 ---------- Previous post was at 20:36 ----------

Deborah

The radius was almost zero when i tried changing the values here and there,it prompted me that the radius of it is supposed to be more than zero.i guess that's where the problems comes from. which i am sure makes sense, isnt it?

Regards
Sajid Mohammed.

\[\lambda\]

rotmanlens said:

]Deborah

The radius was almost zero when i tried changing the values here and there,it prompted me that the radius of it is supposed to be more than zero.i guess that's where the problems comes from. which i am sure makes sense, isnt it?

Regards
Sajid Mohammed.

Click to expand...

Hi Sajid,
yes the radius was small. I was trying to simulate an antenna for which there is a known theoretical result, but it seems that simulating a thin half-wave dipole is impossible - unless there's some parameter one can change so the solver does not generate the error. If I make the radius 1 mm, then HFSS gives a result, but gives a result very different from the theoretical result for a thin dipole. But that's not surprising as r/\[\lambda\]=1/1000=0.001, which is too thick to be considered thin.

I feel a bit frustrated as I have tried simulating some antennas of interest and get what I think are strange results. So I tried to take a step back and convince myself I could simulte a thin dipole - but I seem unable to do that.

Deborah.

Hello Deborah

Would you be interested in sharing the antennas that you have tried to simulate? may be i can learn some from them as well.

Sajid.

rotmanlens said:

Hello Deborah

Would you be interested in sharing the antennas that you have tried to simulate? may be i can learn some from them as well.

Sajid.

Click to expand...

Unfortunatly, the only ones I have here I can't share, but I am in the middle of creating another which I've tried modelling before and not had a lot of luck. I'll post that one when I've finished it.

i am working on an antenna type which might be considered as a prospect for a specific purpose i am involved at academic level.in case if you need any HFSS file ,i have a almost around over 30 different antenna types worked on.would be more than willing to share.

Regards
Sajid Mohammed.