HFSS boundary- detailed explanation about setting boundaries

[skwok]

HFSS boundary

I am designing an underground antenna.

For the radiation box, I set only the top surface as radiation surface. Does this mean I will only see the field radiating from the top surface? All the field from the other 5 sides of the box will be contained underground?

Please help.

Kudo

 

[crucian]

HFSS boundary

Did you set boundary condition?

 

[skwok]

Re: HFSS boundary

Yes, I assigs all the boundaries.

For radiation, I only choose the top surface of the radiation box. I am only interested in field radiated above ground, not underground. Is this correct?

Thanks.

 

[YoungEng]

Re: HFSS boundary

By default if you don't assign a boundary HFSS will make it a perfect E boundary. This means that your antenna will be modeled as if it was placed inside a metallic box an opening at the top. You can create your own surrounding dieletric to imitate the ground that will cover the sides of your antenna. Of course you'll be limited as to the size of this surrounding material depending on the processing power of your computer. At the end planes of this dieletric you can either place a perfect E boundary or an perfecctly matched layer or something in between depending on how you want to model the soil.

 

[skwok]

Re: HFSS boundary

YoungEng:

Thank you for your help.

I had my antenna inside a rectangular box of soil with specific dielectic material to imitate different soil condition.

Then I had air box surrounding this soil box. Again, I assigned the air box top surface for radiation boundary and left all other 5 sides by default.

Do you mean that the sides are perfect E boundary? What do you mean by perfectly matched layer?

Added after 1 hours 22 minutes:

YoungEng:

Is it correct to use "Boundaries, Assign, Layer Impedance" and material setting to set matched layer?

Thanks.

 

[YoungEng]

Re: HFSS boundary

yes it will be a perfect E, you can review your boundary conditions before you simulate using the boundary solver command under the HFSS tab. A perfectly matched layer just means that the fields will be absorbed. It depends if you want the fields to be reflected back to your antenna or just have them absorbed. It might be simpler to make a second radiation boundary to absorb the fields and just look at the radiation pattern of initial radiation boundary at the top of the box.

 

[skwok]

Re: HFSS boundary

YoungEng:

Thank you so much for your help.

Could you please clarify how to make following test conditions?

1) Perfectly matched layer that absorbs all the field

2) A boundary that reflects all the field

Is there any good doucmentation that explains boundary setting? I read HFSS manual before, but I do not remember much detailed explanation about setting boundaries.

Do you know any good 3rd party book on HFSS?

Again, thanks.