# Finite conductivity gives higher loss than solve inside in HFSS

Status
Not open for further replies.

#### yfgchen

##### Newbie level 5
I am simulating a simple stripline in HFSS. The conductor dimension is comparable to the skin depth, so I set "solve inside" for the conductors. Then I also tried "finite conductivity" boundary condition. The loss calculated with the "finite conductivity" condition is higher than the other one. Does it make sense intuitively?

#### streamlet

##### Full Member level 3
How you set the thickness of the conductor when using the "finite conductivity" boundary? Though "solve inside" option used to turn out larger resistance than sheet metal model, you need to pay attention to the thickness setup.

#### yfgchen

##### Newbie level 5
Do you mean the "layer thickness" option in the finite conductivity condition setup? It is left unselected in my simulation. Actually, I don't know what that option does. Shall I assign a value to it?

#### streamlet

##### Full Member level 3
Yes, I mean the "layer thickness" option in the finite conductivity boundary setup. It has a great effect on the simulated resistance especially when the thickness set is smaller than the relevant skin depth.

#### qqpost

##### Member level 1
I met similar problem with yours. Have you figured out how to solve it?

As far as I am concerned, the finite conductivity only can be used when the dimension of the structure is 5 times larger than the skin depth. So you maybe not use the finite conductivity condition here. And I tried several cases. It seems like the "solve inside" result is almost the same as the "solve inside"+”finite conductivity" one.

Any comment?

I am simulating a simple stripline in HFSS. The conductor dimension is comparable to the skin depth, so I set "solve inside" for the conductors. Then I also tried "finite conductivity" boundary condition. The loss calculated with the "finite conductivity" condition is higher than the other one. Does it make sense intuitively?

---------- Post added at 17:09 ---------- Previous post was at 17:07 ----------

I'm not quite understand this layer thickness setting.

What is this "layer"? And when we set the finite conductivity boundary, what is the difference between set on the object and only on the object surface? If we happen to set on the object surface, what does the layer thickness here mean? For exmaple, the thickness of the structure is 10mil, layer thickness of the surface is set at 1mil. So is the rest 9mil seen as perfect conductor with no current? Is that what you mean? Thank you

Yes, I mean the "layer thickness" option in the finite conductivity boundary setup. It has a great effect on the simulated resistance especially when the thickness set is smaller than the relevant skin depth.

#### drops

##### Junior Member level 1
It seems like the "solve inside" result is almost the same as the "solve inside"+”finite conductivity" one.
"solve inside"+”finite conductivity" makes no sense. HFSS can either work with surface currents or with currents inside the conductor volume. I wonder, why this does not rise an error message

#### black_rider799

##### Newbie level 3
why we give infinit ground plan.. what it for...
also why we gave infinite sphere

#### frodonet

##### Member level 2
It thus make perfect sense.

Perfect E = perfect conductivity where there lines or metal strip is considered lossless.

If the conductivity is finite, means thats the transmission lines or metal strip has a certain degree of loss.

Status
Not open for further replies.