Radiation boundary problem in HFSS with antenna simulation

[ifelix]

Re: Radiation boundary problem in HFSS with antenna simulati

Hi,
I've uploaded the file in attach. I've named it lamp.hfss.pdf so I can upload it. to open with HFSS remove the .pdf extensions and it works.
One big question: I've created a radiation boundary with the box of air as in figure.
I would know if when the software calculates the quantities for the far-field setup they are correct. In other words is this kind of box right for that model?
I'm not sure it is ok...maybe it would be better to place the antenna in the center of the big box(or a sphere of air in the same way) but the problem in that case is that I can't define the waveport INSIDE the air box or sphere.
In the case my model isn't right how can I do to put the antenna entirely in a box mantaining the waveport?
It's possible that the front face of the air box is too near to the antenna to cause wrong values for radiated quantities calculation?
Thanks in adv.

Added after 1 minutes:

sorry this is the file

 

[jallem]

I think you have two options:
1) Use a lumped port and move the antenna to the
center of the cube
2) Extend the strip and still use a waveport.

And there even one more option is to use a waveport
with a "cap"

 

[ifelix]

Re: Radiation boundary problem in HFSS with antenna simulati

Hi Jallem,
as you have seen in my attachment I've simulated the first of your suggestions. I've put the antenna in the centre of the cube and applied a lumped port but the result I obtain is totally wrong...
what's the problem?
Thanks...

Added after 11 minutes:

Sorry...the models are in the other post...
however can you explain me clearly what is and how I can realize a cap?
thanks a lot!

 

[jallem]

Re: Radiation boundary problem in HFSS with antenna simulati

I ran your file and the results are as shown. You can see the impedance
and the return loss are good but the radiation are bad.
This happened to me when the dimensions of the radiation box are small
with respect to the frequency. I did not do a redimensioning so far, but all I can
say is that HFSS is famous for this problem, for low frequencies the dimensions
become so big that it takes a long time to simulate, that is way I have not tried
yet.