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do I need to enter loss tangent data for a dielectric in HFSS?

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kae_jolie

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Or does HFSS calculate it for you? I only entered the permittivity and conductivity for the dielectric material. Also, the solution frequency is entered. So, I assume HFSS can calculate loss tangent using tan δ = σ/ωε.

Is it going to affect the results much leaving it out?

Thanks.
 

Loss tangent is an inherent property of a material and depicts the amount of dielectric loss in a material. tan δ = ε''/ε', where the complex permittivity of the material is ε* = ε'-jε''. So, you actually need to enter this into HFSS since it can affect your results. The conductivity of a substrate (σ) deals with conductor losses, and the loss mechanism is completely independent of dielectric loss.

Hope this answers your question.
 

Thanks. What else besides loss tangent do I need to enter under dielectric properties so I don't have to redo my experiments for the fifth time.

Thanks.
 

For substrates that are isotropic (have properties the same in every direction), non-magnetic and non-dispersive (have properties independent of frequency) define:
Dielectric constant, Loss tangent, Conductivity

For nonisotropic materials, make sure you define the above parameters in every direction.
For magnetic materials, define relative permeability and magnetic loss tangent.
For dispersive materials, define all relevant parameters as a function of frequency.

Since I'm not sure what exactly you are trying to simulate, I have tried to be as general as possible. For more specific answers, I need to know what materials you are trying to define.
 

I am trying to simulate a fat/muscle tissue with a dipole antenna to measure how much power absorbed by the fat/muscle tissue.

Having said that, I posted a related question at https://www.edaboard.com/threads/208350/#post879673
that I would appreciate if you answer it. You seem to know your stuff pretty good.

Thanks.

---------- Post added at 04:03 ---------- Previous post was at 03:58 ----------

So, I take it my fat/muscle tissue model would fall under dispersive materials, and I should define permittivity, "dielectric loss tangent" and conductivity.
 

I'm not the best at antennas or modeling tissue, but from what I understand, fat/tissue is dispersive and nonisotropic. So your simulation accuracy depends on how well you define dielectric constant, dielectric loss tangent and conductivity of tissue as a function of direction and frequency. Since this is a well studied topic in literature, I'm sure you will find good papers on this subject.

I'll try to answer your other post.
 
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