# Some questions about simulation in HFSS

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#### duynq.mipt

##### Newbie level 3
Hello everyone! I'm new in HFSS. And I have some questions.
1. What is Mesh in HFSS? and how does HFSS calculate return loss?

2. What's Order of basic functions in Solution Setup/Options? There are Zero, First, Second and Mixed Order, and which order is suitable to simulate planar antenna, TEM Horn...?

3. Which Sweep I need to choose for UWB antenna? For example, I designed UWB planar antenna from 3-6 GHz, I selected Discrete sweep with steep 0.1.

Thanks all.

#### PlanarMetamaterials

Welcome, duynq.mipt

1. What is Mesh in HFSS?

The discretization of the computational domain into tetrahedrons.

how does HFSS calculate return loss?

Using a wave port, it calculates the power and "voltage" (by default) on a port. Then it calculates the difference in this quantity for the incident and total fields. You can get the exact equation in the help docs.

What's Order of basic functions in Solution Setup/Options?

The curvilinear nature of the basis functions used to compute the fields in each tetrahedron. Study the FEM method to understand this further.

which order is suitable to simulate planar antenna, TEM Horn...?

I usually stick with first order, but it depends on your field structure. For a TEM horn I'd stick with first.

Which Sweep I need to choose for UWB antenna?

Only discrete is to be trusted. If you don't mind some possible error in the behavior indicated by the S-parameters, then other types such as fast will do.

duynq.mipt

### duynq.mipt

Points: 2

#### duynq.mipt

##### Newbie level 3
Welcome, duynq.mipt

The discretization of the computational domain into tetrahedrons.

Using a wave port, it calculates the power and "voltage" (by default) on a port. Then it calculates the difference in this quantity for the incident and total fields. You can get the exact equation in the help docs.

The curvilinear nature of the basis functions used to compute the fields in each tetrahedron. Study the FEM method to understand this further.

I usually stick with first order, but it depends on your field structure. For a TEM horn I'd stick with first.

Only discrete is to be trusted. If you don't mind some possible error in the behavior indicated by the S-parameters, then other types such as fast will do.

Thanks for your post. I red somewhere that HFSS calculates E-field in each tetrahedron, and based on this E-field, it calculates S-parameters. I can't imagine about that, and get confused. Could u pls give me the link help docs, I can't find it.

And I usually select first order, sometimes mixed order for planar antenna, and get slightly different results.

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